CN114991690A

CN114991690A - Formation pressure test while drilling method and device

Info

Publication number: CN114991690A
Application number: CN202111016552.8A
Authority: CN
Inventors: 刘伟; 付加胜; 赵庆; 李牧; 翟小强; 张瑞凇; 王振; 张国斌; 罗良波
Original assignee: China National Petroleum Corp; CNPC Engineering Technology R&D Co Ltd
Current assignee: China National Petroleum Corp; CNPC Engineering Technology R&D Co Ltd; Beijing Petroleum Machinery Co Ltd
Priority date: 2021-08-31
Filing date: 2021-08-31
Publication date: 2022-09-02
Anticipated expiration: 2041-08-31
Also published as: CN114991690B

Abstract

The invention provides a formation pressure while drilling testing method and a device. The device includes: the device comprises a flow measuring unit, a pressure measuring unit and a pressure control system; the flow measurement unit comprises a pump-in drilling fluid flow measurement device and a flow measurement device for a backflow drilling fluid; the pumping drilling fluid flow metering equipment is used for metering the flow of the drilling fluid injected into the drilling system, and the flowback drilling fluid flow metering equipment is used for metering the flow of the drilling fluid discharged from the drilling system; the pressure measurement unit comprises a riser pressure gauge, an annulus pressure measurement while drilling tool and a wellhead pressure gauge; the vertical pipe pressure gauge is arranged at the vertical pipe manifold; the annular pressure measurement while drilling tool is arranged in the bottom drilling tool assembly and used for measuring annular pressure; the wellhead pressure gauge is arranged on a wellhead return pipeline and used for measuring the pressure of drilling fluid returned from the wellhead; the pressure control system comprises back pressure control equipment arranged on a well mouth return pipeline and is used for regulating and controlling the well mouth back pressure.

Description

Formation pressure test while drilling method and device

Technical Field

The invention relates to a formation pressure test method and a device while drilling, belonging to the technical field of petroleum and natural gas drilling and completion, natural gas hydrate drilling and production and intelligent drilling.

Background

In drilling engineering, formation pore pressure, fracture pressure, is a key geomechanical parameter in measuring wellbore stability. Among these, formation pore pressure is of particular importance.

The common formation pore pressure determination method is to estimate the pore pressure by using seismic and well logging data and drilling parameters; however, due to parameter errors and the influence of uncertain geological factors, the estimated and predicted formation pore pressure often has large uncertainty, and the accuracy is difficult to guarantee. Formation pore pressure and formation fracture pressure, as determined using while-drilling data, are relatively accurate, typically by two methods: one method is indirectly obtained through data such as measurement while drilling engineering, well logging and the like, such as a mechanical drilling rate method, a d index method, a dc index method, a standardized drilling rate method, a shale density method and a c index method, and the method is relatively rough, has low precision, is more suitable for approximate estimation and prediction, and cannot effectively determine the true values of the formation pore pressure and the fracture pressure; the second method is directly measured by a special formation pore pressure tester or a formation pressure testing instrument while drilling, for example, a traditional cable formation pressure tester, and the method needs to independently lower a testing pipe column, occupies long drilling rig time and is difficult to lower in an extended reach well and a horizontal well, so that the comprehensive cost is high and the efficiency is low. At present, a formation pressure tester while drilling, such as Testrak and GeoTAP, which is used internationally is advanced, a cable probe, a polar plate and a quartz pressure sensor are used for performing pressure testing during the suspension period of single joint connection and the like of drilling operation, but normal drilling construction is delayed to a certain extent, and the comprehensive cost is high; in addition, the Formation pressure Tester while drilling (RFT) Tester and Drill String Tester (DST) are relatively time consuming and labor consuming.

Disclosure of Invention

The invention aims to provide a formation pressure test method and a device while drilling, which can quickly and accurately determine formation pore pressure and/or formation fracture pressure.

In order to achieve the above object, the present invention provides a formation pressure while drilling testing apparatus, wherein the apparatus comprises:

the device comprises a flow measuring unit, a pressure measuring unit and a pressure control system;

the flow measurement unit comprises a pump-in drilling fluid flow measurement device and a flow measurement device of a backflow drilling fluid; the pumping drilling fluid flow metering equipment is used for metering the flow of the drilling fluid injected into the drilling system, and the flow metering equipment of the flowback drilling fluid is used for metering the flow of the drilling fluid discharged from the drilling system;

the pressure measurement unit comprises a riser pressure gauge, an annulus pressure measurement while drilling tool and a wellhead pressure gauge; the riser pressure gauge is arranged at the riser manifold; the annular pressure measurement while drilling tool is arranged in the bottom drilling tool assembly and used for measuring annular pressure; the wellhead pressure gauge is arranged on a wellhead return pipeline and used for measuring the pressure of drilling fluid returned from a wellhead;

the pressure control system comprises back pressure control equipment arranged on a wellhead return pipeline and used for regulating and controlling wellhead back pressure.

In the formation pressure while drilling testing device, preferably, the pumping drilling fluid flow metering device comprises a slurry pump inlet flowmeter and a slurry make-up pump inlet flowmeter; the mud pump inlet flowmeter is arranged at an inlet pipeline of a mud pump for supplying liquid to the stand pipe and is used for metering the flow of the drilling liquid pumped into the stand pipe; the inlet flowmeter of the slurry supplement pump is arranged at an inlet pipeline of a slurry supplement pump of a drilling fluid slurry supplement pipeline and is used for measuring the flow of the drilling fluid pumped into the drilling system by the slurry supplement pump; the fluid infusion pipeline refers to a drilling fluid input pipeline used when the drilling fluid in the drilling system establishes ground short circulation.

In the formation pressure testing device while drilling, preferably, the flow metering device for the flowback drilling fluid comprises a drilling fluid outlet flowmeter, and the drilling fluid outlet flowmeter is arranged on a wellhead flowback pipeline and is used for metering the flow of the drilling fluid returned from the wellhead.

In the formation pressure testing device while drilling, preferably, the back pressure control device includes a first pneumatic flat valve and a self-control throttle valve sequentially arranged on a wellhead return pipeline; the first pneumatic control flat valve is used for opening the connection between the automatic control throttling valve and the wellhead, and the automatic control throttling valve realizes regulation and control of wellhead back pressure through remote control of the opening degree of the automatic control throttling valve.

In the formation pressure testing while drilling apparatus described above, preferably, the pressure control system further comprises a second pneumatic flat valve disposed on the drilling fluid make-up line for isolating the drilling fluid make-up line during circulation of the drilling fluid driven by a mud pump supplying fluid to the riser.

In the formation pressure while drilling testing apparatus, preferably, the formation pressure while drilling testing apparatus further comprises an injection system, the injection system comprises an injection pipe and an injection pressure measuring gauge; the injection pipe is composed of a continuous oil pipe, extends into the shaft annulus for a certain depth through a preset opening of a wellhead blowout preventer stack, and the injection pressure measuring meter is arranged at the lowest end of the injection pipe and is used for measuring the pressure of an injection port.

The invention also provides a formation pressure while drilling testing method, which is carried out by using the formation pressure while drilling testing device and comprises the following steps:

gradually reducing the wellhead back pressure, recording the measured riser pressure, annular pressure, wellhead pressure, the flow of the drilling fluid injected into the drilling system and the flow of the drilling fluid discharged from the drilling system in real time, and after reducing the wellhead back pressure each time, utilizing a working condition identification model to judge the bottom overflow of the well based on the measured riser pressure, annular pressure, wellhead pressure, the flow of the drilling fluid injected into the drilling system and the flow of the drilling fluid discharged from the drilling system; if bottom hole overflow occurs or wellhead back pressure is reduced to 0, the wellhead back pressure is not reduced; the working condition identification model is a model for judging the working conditions based on the pressure of the vertical pipe, the pressure of the annulus, the pressure of the wellhead, the flow of the drilling fluid injected into the drilling system and the flow of the drilling fluid discharged from the drilling system; in the process of gradually reducing the wellhead back pressure, the time interval of wellhead back pressure adjustment is not less than the time interval of measurement signal feedback of the annular pressure measurement while drilling tool;

determining the corresponding bottom hole pressure as the formation pore pressure based on the riser pressure, the annular pressure and/or the wellhead pressure before the bottom hole overflow occurs; or; and determining the bottom hole pressure corresponding to the back pressure of 0 based on the riser pressure, the annular pressure and/or the wellhead pressure after the back pressure drop is 0, and further determining that the formation pore pressure is less than the bottom hole pressure corresponding to the back pressure of 0.

In the above method for testing formation pressure while drilling, preferably, the method further comprises:

before the back pressure of a wellhead is gradually reduced, low-density drilling fluid (the drilling fluid with the density lower than that of the original drilling fluid) is injected into a shaft to realize that the bottom pressure reaches a preset value; the predetermined value should be as close as possible to, but not lower than, the formation pore pressure, which one skilled in the art can determine based on the predicted formation pore pressure;

more preferably, in the process of injecting the low-density drilling fluid into the shaft, the pressure of the riser, the pressure of the annulus and the pressure of the wellhead are monitored in real time, and the bottom hole pressure is controlled according to an expected numerical value as far as possible;

more preferably, the injection of the low density drilling fluid into the wellbore is achieved by: injecting a low-density drilling fluid into the annular space at a certain height, and adjusting the density of the original drilling fluid above an injection point, wherein the low-density drilling fluid comprises at least one of a liquid-phase drilling fluid and a gas-phase drilling fluid (preferably a gas-phase drilling fluid); further preferably, the density of the low-density drilling fluid is less than 0.2g/cm of the density of the original drilling fluid ³ ；

More preferably, the injection of the low density drilling fluid into the wellbore is achieved by: displacing the original drilling fluid in the drilling system by injecting a low density drilling fluid through the riser, the low density drilling fluid comprising at least one of a liquid phase drilling fluid and a gas phase drilling fluid (preferably a liquid phase drilling fluid); further preferably, the density of the low-density drilling fluid is less than 0.1g/cm of the density of the original drilling fluid ³ 。

In the preferred technical scheme, the wellhead back pressure is dynamically regulated and controlled after the hydrostatic column pressure is dynamically regulated and controlled, the bottom hole pressure is accurately controlled, the bottom hole pressure can be greatly reduced by injecting low-density drilling fluid or injecting low-density drilling fluid with a certain annular height, and the disadvantage that the formation pore pressure cannot be or is difficult to detect in a conventional drilling mode is overcome.

In the formation pressure while drilling test method, preferably, in the process of gradually reducing the wellhead back pressure, the pressure reduction value of each wellhead back pressure is 0.2-0.5 MPa.

In the formation pressure test while drilling method, preferably, in the process of gradually reducing the wellhead back pressure, the pressure reduction value of the latter wellhead back pressure does not exceed the pressure reduction value of the former wellhead back pressure; in a specific embodiment, the pressure reduction value of the first wellhead back pressure is 0.5MPa, and the pressure reduction value of the last wellhead back pressure is 0.2 MPa.

In the formation pressure while drilling test method, the measurement time interval of the riser pressure and the wellhead pressure is preferably the same as the measurement time interval of the annular pressure.

if the bottom-hole overflow occurs, the wellhead back pressure is not reduced any more, the wellhead back pressure is gradually raised until the bottom-hole overflow disappears, the measured riser pressure, the annular pressure, the wellhead pressure, the flow of the drilling fluid injected into the drilling system and the flow of the drilling fluid discharged from the drilling system are recorded in real time, and after the wellhead back pressure is raised each time, the bottom-hole overflow is judged by utilizing a working condition identification model based on the measured riser pressure, the annular pressure, the wellhead pressure, the flow of the drilling fluid injected into the drilling system and the flow of the drilling fluid discharged from the drilling system;

determining the corresponding bottom hole pressure as a formation pore pressure verification value based on the riser pressure, the annular pressure and/or the wellhead pressure corresponding to the first no longer occurring bottom hole overflow; correcting the determined formation pore pressure based on the formation pore pressure verification value; when the wellhead back pressure is gradually increased, the time interval of wellhead back pressure adjustment is not less than the time interval of measurement signal feedback of the annular pressure measurement while drilling tool;

in the preferred technical scheme, the correctness of the result is effectively ensured through positive and negative bidirectional tests.

In the formation pressure test method while drilling, preferably, the working condition identification model is a trained support vector machine working condition identification model, and can identify working conditions in overflow, leakage, overflow and leakage simultaneous storage and overflow and leakage prevention 4.

In one embodiment, the trained condition recognition model of the support vector machine is determined by:

acquiring historical riser pressure, annular pressure, wellhead pressure, flow of drilling fluid injected into a drilling system, flow data of the drilling fluid discharged from the drilling system and working condition marks, and performing [0,1] normalization processing on the historical riser pressure, the annular pressure, the wellhead pressure, the flow of the drilling fluid injected into the drilling system and the flow data of the drilling fluid discharged from the drilling system to obtain a training data set;

preset one input 5 parameters: the method comprises the following steps of (1) outputting 4 working conditions of riser pressure, annular pressure, wellhead pressure, flow of drilling fluid injected into a drilling system, flow of drilling fluid discharged from the drilling system: a support vector machine model with overflow, leakage, overflow and leakage simultaneous storage and no overflow and leakage;

training a support vector machine model by using a training data set so as to obtain a trained working condition identification model of the support vector machine;

preferably, the preset support vector machine model is an SVM kernel function type, including a linear kernel function, a polynomial kernel function, a radial basis kernel function and/or a multi-layer perceptron kernel function;

preferably, the training of the support vector machine model is performed in a cross-validation manner.

The preferred technical scheme maps the training data set from a low-dimensional space to a high-dimensional feature space by a Support Vector Machine (SVM) method, converts the problem of linear inseparability into the problem of linear divisibility, and realizes that 5 parameters are input: the riser pressure, the annular pressure, the wellhead pressure, the flow of the drilling fluid injected into the drilling system and the flow of the drilling fluid discharged from the drilling system correspondingly output 4 working conditions: overflow, leakage, overflow and leakage are stored simultaneously, and overflow and leakage are avoided. In order to improve the accuracy of early working condition judgment, the data for training is normalized by [0,1], then SVM kernel function types including linear kernel functions, polynomial kernel functions, radial basis kernel functions, multilayer perceptron kernel functions and the like are optimized, and finally cross validation and model optimization are carried out.

In the formation pressure while drilling test method, preferably, the determining bottom-hole overflow by using the operating condition recognition model based on the measured riser pressure, annulus pressure, wellhead pressure, the flow rate of the drilling fluid injected into the drilling system and the flow rate of the drilling fluid discharged from the drilling system comprises:

determining an overflow amount or a leakage amount, determining a column pressure change value, determining an annulus pressure change value, determining a wellhead pressure change value and further determining whether bottom-hole overflow occurs or not based on the measured riser pressure, the measured annulus pressure, the measured wellhead pressure, the measured flow of drilling fluid injected into a drilling system and the measured flow of drilling fluid discharged from the drilling system;

more preferably, the amount of overflow is determined by the following formula:

in the formula: delta Q _Overflow Is the overflow volume; q. q.s _in (t) a flow rate of drilling fluid injected into the drilling system; q. q.s _out (t) is the flow rate of drilling fluid discharged from the drilling system; the interval time t2-t1 is not less than the interval time of the measurement signal feedback of the primary annular pressure measurement while drilling tool (preferably the interval time of the measurement signal feedback of the primary annular pressure measurement while drilling tool);

more preferably, the leakage is determined by the following equation:

in the formula: delta Q _{Leakage net} Is the leakage amount; q. q.s _in (t) the flow rate of drilling fluid injected into the drilling system; q. q of _out (t) is the flow rate of drilling fluid discharged from the drilling system; the interval time t2-t1 is not less than the interval time of measurement signal feedback of the primary annular pressure measurement while drilling tool (preferably the interval time of measurement signal feedback of the primary annular pressure measurement while drilling tool).

In the above method of formation pressure while drilling, preferably, the bottom hole pressure is determined by the following equation:

P _BHP ＝P _PWD +ρ·g·(H _TVD +H _PWD )

in the formula, P _BHP Bottom hole pressure; p _PWD Is the annulus pressure; rho is the drilling fluid density; g is the acceleration of gravity; h _TVD The bottom hole depth; h _PWD The depth of the measuring point is used for measuring the annular pressure.

In the above formation pressure while drilling test method, preferably, the bottom hole pressure is determined by the following formula:

P _BHP ＝P _d +P _H -P _{l_in}

in the formula, P _BHP Bottom hole pressure; p _d Is the riser pressure; p _H The hydrostatic column pressure in the drill string water hole; p _{l_in} The drill string water hole frictional resistance is shown.

In the above method for measuring formation pressure while drilling, preferably, the bottom hole pressure is determined by the following formula:

P _BHP ＝P _h +P _{l_out} +P _back

in the formula, P _BHP Bottom hole pressure; p _h The hydrostatic column pressure of the drilling fluid in the borehole annulus; p is _{l_out} The annular friction resistance of the well bore; p is _back Is the wellhead pressure.

The invention also provides a formation pressure while drilling testing method, which is carried out by using the formation pressure while drilling testing device, and comprises the following steps:

gradually increasing the wellhead back pressure, recording the measured riser pressure, annular pressure, wellhead pressure, the flow of the drilling fluid injected into the drilling system and the flow of the drilling fluid discharged from the drilling system in real time, and performing bottom hole leakage judgment by using a working condition identification model based on the measured riser pressure, annular pressure, wellhead pressure, the flow of the drilling fluid injected into the drilling system and the flow of the drilling fluid discharged from the drilling system after the wellhead back pressure is increased every time; if the bottom hole leakage occurs or the wellhead back pressure rises to the highest value required by the well site, the wellhead back pressure is not raised any more; the working condition identification model is a model for judging the working conditions based on the pressure of the vertical pipe, the pressure of the annulus, the pressure of the wellhead, the flow of the drilling fluid injected into the drilling system and the flow of the drilling fluid discharged from the drilling system; in the process of gradually increasing the wellhead back pressure, the time interval of wellhead back pressure adjustment is not less than the time interval of measurement signal feedback of the annular pressure measurement while drilling tool;

determining the corresponding bottom hole pressure as the formation fracture pressure based on the riser pressure, the annular pressure and/or the wellhead pressure of the previous time of bottom hole leakage; or; and determining that the back pressure is the bottom hole pressure corresponding to the highest value required by the well site based on the riser pressure, the annular pressure and/or the wellhead pressure after the back pressure is increased to the highest value required by the well site, and further determining that the formation fracture pressure is greater than the bottom hole pressure corresponding to the highest value required by the well site.

before the back pressure of a wellhead is gradually increased, high-density drilling fluid (the drilling fluid with the density higher than that of the original drilling fluid) is injected into a shaft to realize that the bottom hole pressure reaches a preset value; the preset value should be as close as possible to, but not higher than, the formation fracture pressure, and one skilled in the art can make the determination based on the predicted formation fracture pressure;

more preferably, in the process of injecting the high-density drilling fluid into the shaft, the pressure of the riser, the pressure of the annulus and the pressure of the wellhead are monitored in real time, and the bottom hole pressure is controlled according to an expected numerical value as far as possible;

more preferably, the injecting of the high density drilling fluid into the wellbore is achieved by: injecting high-density drilling fluid into the annulus at a certain height, and adjusting the density of the original drilling fluid above an injection point; further preferably, the density of the high-density drilling fluid is 0.2g/cm higher than that of the original drilling fluid ³ ；

More preferably, the injecting of the high density drilling fluid into the wellbore is achieved by: injecting high-density drilling fluid through the vertical pipe to replace the original drilling fluid in the drilling system; further preferably, the density of the high-density drilling fluid is 0.1g/cm higher than that of the original drilling fluid ³ 。

In the preferred technical scheme, the wellhead back pressure is dynamically regulated and controlled after the hydrostatic column pressure is dynamically regulated and controlled, the bottom hole pressure is accurately controlled, the high-density drilling fluid or the high-density drilling fluid with a certain annular height is injected, the bottom hole pressure can be greatly improved, and the disadvantage that the stratum fracture pressure cannot be or is difficult to detect in a conventional drilling mode is overcome.

In the formation pressure while drilling test method, preferably, in the process of gradually increasing the wellhead back pressure, the pressure increase value of each wellhead back pressure is 0.2-1.5 MPa.

In the formation pressure while drilling test method, preferably, in the process of gradually increasing the wellhead back pressure, the pressure increase value of the next wellhead back pressure does not exceed the pressure increase value of the previous wellhead back pressure; in a specific embodiment, the first wellhead back pressure has a pressure rise of 1.5MPa, and the last wellhead back pressure has a pressure rise of 0.2 MPa.

if the bottom hole leakage occurs, the wellhead back pressure is not increased any more, the wellhead back pressure is gradually decreased until the bottom hole leakage disappears, the measured riser pressure, the measured annular pressure, the measured wellhead pressure, the measured flow of the drilling fluid injected into the drilling system and the measured flow of the drilling fluid discharged from the drilling system are recorded in real time, and the bottom hole leakage is judged by utilizing a working condition identification model on the basis of the measured riser pressure, the measured annular pressure, the measured wellhead pressure, the measured flow of the drilling fluid injected into the drilling system and the measured flow of the drilling fluid discharged from the drilling system after the wellhead back pressure is decreased every time;

determining the corresponding bottom hole pressure as a formation fracture pressure verification value based on the riser pressure, the annular pressure and/or the wellhead pressure corresponding to the first no longer occurring bottom hole leakage; correcting the determined formation fracture pressure based on the formation fracture pressure verification value; when the wellhead back pressure is gradually reduced, the time interval of wellhead back pressure adjustment is not less than the time interval of measurement signal feedback of the annular pressure measurement while drilling tool;

one input 5 parameters are preset: the method comprises the following steps of (1) outputting 4 working conditions of riser pressure, annular pressure, wellhead pressure, flow of drilling fluid injected into a drilling system, flow of drilling fluid discharged from the drilling system: a support vector machine model with overflow, leakage, overflow and leakage simultaneous storage and no overflow and leakage;

The preferred technical scheme maps the training data set from a low-dimensional space to a high-dimensional feature space by a Support Vector Machine (SVM) method, converts the problem of linear inseparability into the problem of linear divisibility, and realizes that 5 parameters are input: the method comprises the following steps of (1) outputting 4 working conditions correspondingly according to the flow of drilling fluid injected into a drilling system and the flow of the drilling fluid discharged from the drilling system by riser pressure, annular pressure, wellhead pressure: overflow, leakage, overflow and leakage are stored simultaneously, and overflow and leakage are avoided. In order to improve the accuracy of early working condition judgment, the data for training is normalized by [0,1], then SVM kernel function types including linear kernel functions, polynomial kernel functions, radial basis kernel functions, multilayer perceptron kernel functions and the like are optimized, and finally cross validation and model optimization are carried out.

According to the optimal technical scheme, through intelligent data characteristic analysis, the prediction accuracy of the pore pressure and the fracture pressure of the traditional stratum is greatly improved, and uncertain factors are eliminated.

In the formation pressure while drilling test method, preferably, the determining of bottom hole leakage by using the operating condition recognition model based on the measured riser pressure, annulus pressure, wellhead pressure, flow of the drilling fluid injected into the drilling system and flow of the drilling fluid discharged from the drilling system comprises:

determining overflow volume or leakage volume, determining a column pressure change value, determining an annulus pressure change value, determining a wellhead pressure change value and further judging whether bottom hole leakage occurs or not based on the measured riser pressure, annulus pressure, wellhead pressure, the flow of drilling fluid injected into a drilling system and the flow of drilling fluid discharged from the drilling system;

more preferably, the amount of overflow is determined by the following formula:

in the formula: delta Q _Overflow Is the overflow volume; q. q.s _in (t) the flow rate of drilling fluid injected into the drilling system; q. q.s _out (t) is the flow rate of drilling fluid discharged from the drilling system; the interval time t2-t1 is not less than the interval time of the measurement signal feedback of the primary annular pressure measurement while drilling tool (preferably the interval time of the measurement signal feedback of the primary annular pressure measurement while drilling tool);

more preferably, the leakage is determined by the following equation:

in the formula: delta Q _{Leakage net} Is the leakage amount; q. q.s _in (t) a flow rate of drilling fluid injected into the drilling system; q. q.s _out (t) is the flow rate of drilling fluid discharged from the drilling system; the interval time t2-t1 is not less than the interval time of the measurement signal feedback of the primary annular pressure measurement while drilling tool (preferably the primary annular pressure measurement while drilling tool)The interval for making the measurement signal feedback).

P _BHP ＝P _PWD +ρ·g·(H _TVD +H _PWD )

in the formula, P _BHP Is the bottom hole pressure; p _PWD Is the annulus pressure; rho is the drilling fluid density; g is the acceleration of gravity; h _TVD The bottom hole depth; h _PWD The depth of the measuring point is used for measuring the annular pressure.

P _BHP ＝P _d +P _H -P _{l_in}

P _BHP ＝P _h +P _{l_out} +P _back

in the formula, P _BHP Is the bottom hole pressure; p _h The hydrostatic column pressure of the drilling fluid in the borehole annulus; p _{l_out} The annular friction resistance of the well bore; p _back Is the wellhead pressure.

At the present stage, the pressure-controlled drilling technology and equipment can monitor the annular pressure in real time, ensure the accurate control of the bottom hole pressure and accurately monitor the change of the drilling fluid flow through a closed-loop circulating system; the precise control of the well bottom and annular pressure is realized by controlling the back pressure of the well mouth, can be carried out by using a high-precision automatic hydraulic throttling valve and is controlled by an automatic closed-loop control system; drilling fluid return flow, temperature, and density may be measured using a coriolis flowmeter; the riser pressure and wellhead back pressure can be measured by using a precise digital sensor, and the precise control of pressure control is guaranteed. This provides technical support for the implementation of the present invention. According to the technical scheme provided by the invention, the well head back pressure is dynamically regulated and controlled, the well bottom pressure is accurately controlled, the pressure balance between the shaft and the stratum and the occurrence and development conditions of overflow and leakage are monitored, and the changes of annular pressure, column pressure, well head pressure, drilling fluid injection quantity and outflow quantity are analyzed and judged, so that the technical problem that prediction and monitoring of stratum pore pressure and fracture pressure of a complex ultra-deep well and a complex stratum are inaccurate is effectively solved, and the safety control capability of the shaft is improved.

According to the technical scheme provided by the invention, the relative difference between the bottom hole pressure and the formation pore pressure and the formation fracture pressure is controlled by accurately regulating and controlling the bottom hole pressure, and the micro-overflow or micro-leakage state is artificially caused, so that the true values of the formation pore pressure and the formation fracture pressure are accurately obtained. Therefore, the safe operation interval of the pressure of the shaft can be better guided, namely, the upper pressure boundary without leakage and the lower pressure boundary without overflow are kept, so that the loss of time and expenditure caused by underground complexity is avoided, the non-production time is reduced, the comprehensive efficiency and benefit of well drilling are improved, and safe and rapid drilling is realized.

The technical scheme provided by the method of the invention has the following beneficial effects:

(1) compared with the traditional method and process measures, the method can repeatedly test the pore pressure and the fracture pressure of the stratum without stopping the circulation of the drilling fluid.

(2) By regulating and controlling the wellhead back pressure, the bottom hole pressure is quickly changed, and the formation pore pressure and the fracture (leakage) pressure can be quickly measured by an annulus pressure measurement while drilling tool and riser pressure, wellhead back pressure measurement, drilling fluid injection amount and reverse discharge amount measurement.

Drawings

FIG. 1 is a schematic diagram of a formation pressure while drilling testing apparatus according to an embodiment.

FIG. 2A is a graph of annulus pressure measurements when flooding occurs, according to one embodiment.

FIG. 2B is a schematic illustration of drilling fluid injection and outflow when flooding occurs, according to one embodiment.

FIG. 3A is a graph of annulus pressure test values when a leak occurs, in one embodiment.

FIG. 3B is a schematic illustration of the drilling fluid injection and outflow at the time of a loss of fluid in one embodiment.

FIG. 4 is a schematic structural flow diagram of a structure for identifying downhole conditions by a support vector machine condition identification model according to an embodiment of the present invention.

FIG. 5 is a schematic flow chart of a formation pressure while drilling testing method according to an embodiment of the invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be described in detail and completely with reference to the drawings in the embodiments of the present invention. It is to be understood that the embodiments described are only a few embodiments of the present invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Referring to fig. 1, an embodiment of the present invention provides a formation pressure while drilling testing apparatus, wherein the apparatus includes:

the device comprises a flow measuring unit, a pressure measuring unit, an injection system and a pressure control system;

the flow measurement unit comprises a pump-in drilling fluid flow measurement device and a flow measurement device for a backflow drilling fluid; the pumping drilling fluid flow metering equipment is used for metering the flow of the drilling fluid injected into the drilling system, and the flowback drilling fluid flow metering equipment is used for metering the flow of the drilling fluid discharged from the drilling system; the flow metering equipment for the drilling fluid comprises a mud pump inlet flowmeter 1 and a mud pump inlet flowmeter 8, and the flow metering equipment for the drilling fluid for the back discharge comprises a drilling fluid outlet flowmeter 12; the mud pump inlet flowmeter 1 is arranged at an inlet pipeline of a mud pump 2 for supplying liquid to the stand pipe and is used for metering the flow of the drilling liquid pumped into the stand pipe; the slurry supplement pump inlet flowmeter 8 is arranged at an inlet pipeline of a drilling fluid supplement pipeline slurry supplement pump (not shown in figure 1) and is used for metering the flow of the drilling fluid pumped into the drilling system by the slurry supplement pump; the drilling fluid outlet flowmeter 12 is arranged on a wellhead return pipeline and used for metering the flow of drilling fluid returned from a wellhead;

the pressure measurement unit comprises a riser pressure gauge 3, an annulus pressure measurement while drilling tool 6 and a wellhead pressure gauge 9; the vertical pipe pressure gauge 3 is arranged at the vertical pipe manifold; the annulus pressure measurement while drilling tool 6 is arranged in the bottom drilling tool assembly and used for measuring annulus pressure; the wellhead pressure gauge 9 is arranged on a wellhead return pipeline and is used for measuring the pressure of drilling fluid returned from a wellhead;

the pressure control system comprises back pressure control equipment arranged on a well mouth return pipeline and a second pneumatic flat valve 7, and is used for regulating and controlling the well mouth back pressure; the back pressure control equipment comprises a first pneumatic control flat valve 10 and a self-control throttle valve 11 which are sequentially arranged on a well head return pipeline; the first pneumatic control flat valve 10 is used for opening the connection between the automatic control throttle valve 11 and a wellhead, and the automatic control throttle valve 12 realizes regulation and control of wellhead back pressure by remotely controlling the opening degree; the second air-control flat valve 7 is arranged on the drilling fluid slurry supplementing pipeline and is used for isolating the drilling fluid slurry supplementing pipeline during the period of driving the drilling fluid circulation by using a slurry pump for supplying liquid to the stand pipe; the first pneumatic control flat valve 10, the wellhead pressure gauge 9, the automatic control throttle valve 11 and the drilling fluid outlet flowmeter 12 are arranged in sequence along the direction from the inlet to the outlet of a wellhead return pipeline, namely the first pneumatic control flat valve 10, the wellhead pressure gauge 9, the automatic control throttle valve 11 and the drilling fluid outlet flowmeter 12 are arranged in sequence;

the injection system comprises an injection pipe 4 and an injection pressure measuring meter 5; the injection pipe 4 is composed of a continuous oil pipe, extends into the shaft annulus for a certain depth through a preset opening of a wellhead blowout preventer group, and the injection pressure measuring meter 5 is arranged at the lowest end of the injection pipe to measure the pressure of an injection port.

Wherein, mud pump entry flowmeter 1 can select ultrasonic mass flowmeter for use, and drilling fluid export flowmeter 12 can select mass flowmeter for use.

The fluid infusion pipeline refers to a drilling fluid input pipeline used when the drilling fluid in the drilling system establishes ground short circulation, and the outlet end of the fluid infusion pipeline is communicated with the wellhead return pipeline and is close to the inlet end of the wellhead return pipeline; in the invention, the setting point of the outlet end of the fluid infusion pipeline on the return pipeline is closer to the inlet end of the well head return pipeline than the pressure gauge 9 of the well head.

The invention provides a formation pressure while drilling testing method, which is carried out by using the formation pressure while drilling testing device provided by the embodiment, and comprises the following steps:

step S11: gradually reducing wellhead back pressure, recording the measured riser pressure, annular pressure, wellhead pressure, the flow of drilling fluid injected into a drilling system and the flow of drilling fluid discharged from the drilling system in real time, and judging the bottom overflow well by using a working condition identification model based on the measured riser pressure, annular pressure, wellhead pressure, the flow of drilling fluid injected into the drilling system and the flow of drilling fluid discharged from the drilling system after reducing the wellhead back pressure each time; if bottom hole overflow occurs or wellhead back pressure is reduced to 0, the wellhead back pressure is not reduced; the working condition identification model is a model for judging the working conditions based on the pressure of the vertical pipe, the pressure of the annulus, the pressure of the wellhead, the flow of the drilling fluid injected into the drilling system and the flow of the drilling fluid discharged from the drilling system; in the process of gradually reducing the wellhead back pressure, the time interval of wellhead back pressure adjustment is not less than the time interval of measurement signal feedback of the annular pressure measurement while drilling tool;

step S12: determining the corresponding bottom hole pressure as the formation pore pressure based on the riser pressure, the annular pressure and/or the wellhead pressure before the bottom hole overflow occurs; or; and determining the bottom hole pressure corresponding to the back pressure of 0 based on the riser pressure, the annular pressure and/or the wellhead pressure after the back pressure drop is 0, and further determining that the formation pore pressure is less than the bottom hole pressure corresponding to the back pressure of 0.

If no overflow occurs after the wellhead back pressure is reduced to zero, the influence of the formation pore pressure can be eliminated from consideration in the drilling process in principle.

Further, the method further comprises:

before proceeding to step S10, step S0 is performed:

injecting low-density drilling fluid (the drilling fluid with the density lower than that of the original drilling fluid) into the shaft to realize that the bottom hole pressure reaches a preset value; the preset value should be as close as possible to, but not lower than, the formation pore pressure, and one skilled in the art can make the determination based on the predicted formation pore pressure;

during the process of injecting the low-density drilling fluid into the shaft, the pressure of the riser, the pressure of the annulus and the pressure of the wellhead can be monitored in real time, and the bottom hole pressure is controlled according to an expected numerical value as far as possible;

further, injecting the low density drilling fluid into the wellbore is accomplished by: injecting a low-density drilling fluid into the annular space at a certain height, and adjusting the density of the original drilling fluid above an injection point, wherein the low-density drilling fluid comprises at least one of a liquid-phase drilling fluid and a gas-phase drilling fluid (preferably a gas-phase drilling fluid); wherein the low-density drilling fluid preferably has a density of 0.2g/cm lower than that of the original drilling fluid ³ The drilling fluid of (1);

further, injecting the low density drilling fluid into the wellbore is accomplished by: injecting a low density drilling fluid through the riser to displace the original drilling fluid in the drilling system, the low density drilling fluid comprising at least one of a liquid phase drilling fluid and a gas phase drilling fluid (preferably a liquid phase drilling fluid); wherein the low-density drilling fluid preferably has a density of 0.1g/cm lower than that of the original drilling fluid ³ The drilling fluid of (1).

In the above preferred technical solution, under the condition that other drilling parameters are not changed, the density of the drilling fluid above the injection point is adjusted, and if the injected drilling fluid is a liquid phase, the change of the bottom hole pressure is:

ΔP＝ΔρgH

in the formula: the delta rho is the density difference between the injected drilling fluid and the original drilling fluid; g is the acceleration of gravity; h is the height of the injection point; it follows that if the injection depth is not changed, the drilling fluid density change is:

bottom hole pressure changes over time:

in the formula: q (t) _in The accumulation amount of the low-density drilling fluid returning to the injection hole is obtained, and the time is started from the returning to the injection hole; s _a Is the annulus area;

if the drilling fluid density change is determined, the injection depth needs to be adjusted as follows:

typically, because coiled tubing depth is already fixed and adjustments are more demanding on wellhead sealing, methods of varying drilling fluid density are commonly used. If the injected drilling fluid is in a gas phase, the change of the bottom hole pressure becomes more complex, mainly reflected in the process that the gas moves upwards, the influence on the change of the average hydrostatic column pressure is more complex due to continuous collision of the volume and continuous reduction of the pressure, but the pressure change can be more accurate by using special fluid calculation software, and in addition, the injection pressure measuring meter can also accurately monitor the change process of the whole pressure so as to ensure that the bottom hole pressure is regulated and controlled according to an expected value.

In the preferred technical scheme, the bottom hole pressure is finely adjusted by roughly adjusting the bottom hole pressure by changing the density of the drilling fluid once and changing the back pressure of a wellhead for multiple times, so that the determination of the formation pore pressure can be realized more quickly and conveniently.

Further, in the process of gradually reducing the back pressure of the wellhead, the pressure reduction value of the back pressure of the wellhead each time is 0.2-0.5 MPa.

Further, in the process of gradually reducing the wellhead back pressure, the pressure reduction value of the next wellhead back pressure does not exceed the pressure reduction value of the previous wellhead back pressure; for example, the pressure reduction value of the wellhead back pressure is 0.5MPa for the first time, and then the pressure reduction value of the wellhead back pressure is gradually reduced each time until the pressure reduction value of the wellhead back pressure is 0.2 MPa.

The change of the wellhead back pressure can quickly adjust the bottom hole pressure, the wellhead pressure, the riser pressure and the annular pressure (PWD measured value) form mutual influence, the change values of the bottom hole pressure, the wellhead pressure, the riser pressure and the annular pressure (PWD measured value) in a certain time period have certain equivalence, the wellhead back pressure and the riser pressure change ground are easy to observe, the signal feedback is quick, the annular pressure (PWD measured value) signal feedback which is one of the underground complex key factors such as overflow, leakage and the like can be quickly judged and lags for 3-5 minutes, but is closer to an underground complex occurrence place, and the underground complex characteristic analysis main influence factor is realized. Searching for impossible to put the formation pressure in place in one step, and optimizing the amplitude and the number of pressure adjustments per time, i.e.

ΔP _step，n May be the same or different. In order to facilitate testing of the formation pore pressure, a larger pressure adjusting amplitude is set at the initial stage, after the estimated value of the formation pressure is approached, a smaller pressure adjusting amplitude is adopted, the minimum value of the pressure adjusted at each step is influenced by the control precision of the wellhead pressure, the highest value is required by the formation pressure testing precision, and in the common drilling design, the drilling fluid column pressure and the circulating pressure consumption are close to the formation pore pressure, so that the reduction of the wellhead back pressure can be set to be 0.2-0.5MPa, and the pressure is gradually reduced to 0.2MPa from the larger value of 0.5 MPa.

Further, the measurement time interval time of the riser pressure and the wellhead pressure is the same as the measurement time interval of the annular pressure.

Further, the method further comprises:

step S13: if the bottom-hole overflow occurs, the wellhead back pressure is not reduced any more, the wellhead back pressure is gradually increased until the bottom-hole overflow disappears, the measured riser pressure, the annular pressure, the wellhead pressure, the flow of the drilling fluid injected into the drilling system and the flow of the drilling fluid discharged from the drilling system are recorded in real time, and after the wellhead back pressure is increased each time, the bottom-hole overflow judgment is carried out by utilizing a working condition identification model on the basis of the measured riser pressure, the annular pressure, the wellhead pressure, the flow of the drilling fluid injected into the drilling system and the flow of the drilling fluid discharged from the drilling system;

in the preferred technical scheme, the correctness of the result is effectively ensured through a positive and negative bidirectional test.

Further, the bottom hole pressure is determined based on the annulus pressure, in particular by the following equation:

P _BHP ＝P _PWD +P _lh +P _hc

in the formula, P _BHP Is the bottom hole pressure; p _PWD Is the annulus pressure; p _lh The drilling fluid hydrostatic column pressure below a measuring point for measuring the annular pressure; p _hc The method comprises the following steps of (1) measuring the annular friction resistance of a borehole below a measuring point of annular pressure;

under normal drilling conditions, the distance between an annular pressure measurement while drilling tool (PWD tool) and the bottom of a well is very close, and the length of the annular pressure measurement while drilling tool is generally less than 20-30 meters, so that the sum of the hydrostatic column pressure of drilling fluid from a measuring point for measuring the annular pressure to the bottom of the well and the annular friction resistance of a borehole is relatively small, and the bottom pressure can be determined by the following formula:

P _BHP ＝P _PWD +ρ·g·(H _TVD +H _PWD )

Further, the bottom hole pressure is determined based on the riser pressure, in particular by the following equation:

P _BHP ＝P _d +P _H -P _{l_in}

Further, the bottom hole pressure is determined based on the wellhead pressure, specifically by the following equation:

P _BHP ＝P _h +P _{l_out} +P _back

in the formula, P _BHP Bottom hole pressure; p is _h The hydrostatic column pressure of the drilling fluid in the borehole annulus; p _{l_out} The annular friction resistance of the well bore; p _back Is the wellhead pressure.

Further, the working condition identification model is a trained support vector machine working condition identification model, and can realize identification of working conditions in overflow, leakage, overflow and leakage simultaneous storage and overflow and leakage prevention 4;

further, the trained support vector machine working condition identification model is determined by the following method:

one input 5 parameters are preset: the pressure of a stand pipe, the pressure of an annulus, the pressure of a wellhead, the flow of drilling fluid injected into a drilling system, the flow of the drilling fluid discharged from the drilling system and 4 working conditions of output are as follows: a support vector machine model with overflow, leakage, overflow and leakage simultaneous storage and no overflow and leakage;

training a support vector machine model by utilizing a training data set so as to obtain a trained working condition recognition model of the support vector machine;

the preset support vector machine model preferably selects SVM kernel function types, including linear kernel functions, polynomial kernel functions, radial basis kernel functions and/or multilayer perceptron kernel functions and the like;

in which, when the support vector machine model is trained, it is better to adopt the cross-validation method.

The preferred technical scheme maps the training data set from a low-dimensional space to a high-dimensional feature space by a Support Vector Machine (SVM) method, converts the problem of linear inseparability into the problem of linear divisibility, and realizes that 5 parameters are input: the method comprises the following steps of (1) outputting 4 working conditions correspondingly according to the flow of drilling fluid injected into a drilling system and the flow of the drilling fluid discharged from the drilling system by riser pressure, annular pressure, wellhead pressure: overflow, leakage, overflow and leakage are stored simultaneously, and overflow and leakage are avoided. In order to improve the accuracy of early working condition judgment, the data for training is normalized by [0,1], then SVM kernel function types including linear kernel functions, polynomial kernel functions, radial basis kernel functions, multilayer perceptron kernel functions and the like are optimized, and finally cross validation and model optimization are carried out;

in a specific embodiment, a schematic flow diagram of a working condition structure for identifying the trained working condition recognition model of the support vector machine is shown in fig. 4.

Further, the determining of the bottom-hole overflow by using the working condition recognition model based on the measured pressure of the riser, the measured annular pressure, the measured wellhead pressure, the measured flow of the drilling fluid injected into the drilling system, and the measured flow of the drilling fluid discharged from the drilling system includes:

determining the overflow amount or leakage amount, determining the pressure change value of an upright column, determining the annular pressure change value, determining the wellhead pressure change value and further judging whether bottom hole overflow occurs or not based on the measured riser pressure, annular pressure, wellhead pressure, the flow of drilling fluid injected into a drilling system and the flow of the drilling fluid discharged from the drilling system;

further, the amount of overflow is determined by the following formula:

in the formula: delta Q _Overflow Is the overflow volume; q. q.s _in (t) is the flow of drilling fluid injected into the drilling systemAn amount; q. q.s _out (t) is the flow rate of drilling fluid discharged from the drilling system; the interval time t2-t1 is not less than the interval time of the measurement signal feedback of the primary annular pressure measurement while drilling tool (preferably the interval time of the measurement signal feedback of the primary annular pressure measurement while drilling tool);

further, the leakage amount is determined by the following formula:

in the formula: delta Q _{Leakage net} Is the leakage amount; q. q of _in (t) the flow rate of drilling fluid injected into the drilling system; q. q.s _out (t) is the flow rate of drilling fluid discharged from the drilling system; the interval time t2-t1 is not less than the interval time of the measurement signal feedback of the primary annular pressure measurement while drilling tool (preferably the interval time of the measurement signal feedback of the primary annular pressure measurement while drilling tool);

under the normal circulation condition, the flow data of the drilling fluid injected into the drilling system is from a mud pump inlet flowmeter 1, and can also be calculated through the discharge capacity of the mud pump checked by a drilling fluid outlet flowmeter 12; and (4) stopping the operation of the slurry pump, and reading data of an inlet flowmeter 8 of the slurry supplement pump when the ground short circulation control bottom hole pressure is established through the slurry supplement pump. The source of the flow data for the drilling fluid exiting the drilling system is a drilling fluid outlet flow meter 12.

Neglecting the influences of the elasticity of the shaft and the drilling fluid, and the like, the return variation of the wellhead is controlled by the variation of the bottom hole pressure and the formation pressure difference. The magnitude of the flow variation is a main basis for judging the underground overflow or leakage, wherein the integral duration is a key factor and is generally required to be 3-5 minutes, namely the interval of t2-t1 is 3-5 minutes, the technical requirement is to include an annular pressure measurement feedback value as much as possible and to provide a time interval for the drilling fluid to circularly flow in and flow out and to leave enough flow integral accumulation, generally, the delta Q is more than +/-0.1 m ³ The warning threshold value is properly prolonged along with the increase of the well depth and the complexity of the stratum;

still further, the method further comprises performing a coefficient determination of cumulative changes in outlet flow versus changes in bottom hole pressure:

setting the cumulative outlet flow change to be in a linear relation with the bottom hole pressure change:

ΔQ＝k·ΔP _BF

Δ Q is the overflow or leakage; k. is a proportionality coefficient; delta P _BF The pore pressure of the stratum and the bottom hole pressure difference are obtained;

and fitting to obtain a proportionality coefficient based on the overflow or leakage data and the determined formation pore pressure data.

In a specific embodiment, overflow discrimination is performed based on overflow or leakage, column pressure variation, annulus pressure variation, wellhead pressure variation, annulus pressure, and column pressure, specifically:

the calibration standards for gas flooding occurred were: the overflow volume is greater than a first rated value (positive) or the leakage volume is less than a second rated value (negative), the column pressure change value, the annular pressure change value and the wellhead pressure change value deviate (the three values are equal or close in normal working conditions), the annular pressure continuously gradually decreases after temporarily gradually increasing in comparison with the annular pressure change trend line under normal working conditions, and the column pressure gradually decreases in comparison with the annular pressure change trend line under normal working conditions; as shown in fig. 2A, 2B;

the calibration standards for liquid overflow to occur were: the overflow volume is greater than the first rated value (should be positive) or the leakage volume is less than the second rated value (should be negative), the column pressure variation value, the annular pressure variation value and the wellhead pressure variation value deviate (in normal working conditions, the three values are equal or close), the annular pressure is continuously and gradually lower compared with the variation trend line of the annular pressure under the normal working conditions, and the column pressure is gradually lower compared with the variation trend line of the column pressure under the normal working conditions.

When gas overflow occurs, gas passes through a well wall barrier, the pressure is not fully released, the gas pressure is basically the formation pressure, the measured value of the annular pressure is characterized in that the pressure is temporarily increased, the riser pressure has no obvious change characteristic at the moment, but along with the circulation of the drilling fluid, bubbles rise along the well annular space, the volume is gradually expanded, the bubbles are gathered, the circulating density of the drilling fluid can be obviously reduced, the measured value of the annular pressure is characterized in that the measured value is continuously reduced, the riser pressure is continuously reduced, the outflow flow of the drilling fluid return outlet is continuously greater than the fluid flow pumped by a mud pump, and the leakage quantity is continuously increased negatively or the overflow quantity is continuously increased positively.

When liquid overflow occurs, the formation liquid is generally oil or water, the density is smaller than the density of the general drilling fluid, the original pressure is rapidly reduced to the wellbore pressure through the well wall barrier due to the influence of expansibility, only the density of the formation fluid generates the density of the circulating drilling fluid, but the pressure difference between the bottom hole pressure and the formation pressure is small and the time is short, so that the volume of the overflow formation liquid is relatively small, the characteristics of annular pressure measurement value and riser pressure change are relatively moderate, the annular pressure measurement value and riser pressure change slowly and continuously decrease, the outflow flow of the drilling fluid return outlet is continuously larger than the fluid flow pumped by the mud pump, and the leakage amount is continuously increased negatively or the overflow amount is continuously increased positively.

Under the condition that drilling flow and other parameters are not changed, the hydrostatic column pressure of drilling fluid and the annular friction resistance of a well bore can not be changed, and a wellhead back pressure control value is adjusted to cause the change of bottom hole pressure to be: delta P _BHP ＝ΔP _back . Under normal drilling conditions, the distance between an annular pressure measurement while drilling tool (PWD tool) and the bottom of a well is very close, and the length is generally less than 20-30 meters, so that the sum of the hydrostatic column pressure of drilling fluid from a measuring point for measuring the annular pressure to the bottom of the well and the annular friction resistance of a borehole is relatively small, under the conditions of small borehole track adjustment and small drilling fluid discharge change, the change can be approximately considered as no change, and the change value of the bottom-hole pressure is delta P (delta P) which is equal to delta P _PWD . Under the condition that other parameters are not changed, the hydrostatic column pressure in the drill string water hole and the frictional resistance of the drill string water hole are not changed, and the change value of the bottom hole pressure is delta P-delta P _BHP ＝ΔP _d . Therefore, if no abnormal working conditions such as underground complexity and the like occur and the space attitude of the PWD tool is obviously changed, the numerical values are approximately consistent and have the equivalence of underground complex judgment, but the signal feedback time is different, the change of wellhead back pressure is fastest, and the pressure of the vertical pipe is less than the set pressureHowever, the pressure wave signal (the propagation speed of the pressure wave is 1500-2000m/s in the liquid phase drilling fluid) is mainly transmitted and influenced, the phase difference is in the second level, the PWD pressure return value is slowest, the transmission bandwidth of the instrument is influenced, the change of the wellhead return pressure value is lagged for about 3-5 minutes, and the significance of capturing the change of the PWD return pressure value on whether the bottom hole overflows or leaks is great.

The normal feedback characteristic of the measured value of the annular pressure is as follows:

P _PWD (t+Δt)＝P _PWD (t)+ρgΔH(Δt)+f(Δl _out (Δt))

in the formula, P _PWD Is the annulus pressure; rho is the drilling fluid density; g is the acceleration of gravity; h _TVD The bottom hole depth; Δ H is the vertical depth of PWD descent at Δ t time (same as the vertical depth of drilling at Δ t time); f (Δ l) _out (Δ t)) is the increase in annular friction caused by the depth of PWD run-down/drilling.

The normal feedback characteristic of the pressure of the stand pipe is as follows:

P _d (t+Δt)＝P _d (t)+f(Δl _in (Δt))+f(Δl _out (Δt))

in the formula, P _d Is the riser pressure; h _TVD The bottom hole depth; f (Δ l) _in (Δ t)) is the increase in pressure loss in the water hole due to the increase in the length of the drill string water hole caused by the drilling depth within the time Δ t; f (Δ l) _out (Δ t)) is the increase in annular friction caused by the depth of PWD run-down/drilling.

As the drilling depth increases, the annulus pressure measurement and the riser pressure measurement should be substantially consistent if there is no change in other parameters and conditions, and if not, it means that the upper formation may overflow or leak, or even the string may become plugged or broken.

The formation pressure while drilling testing method is suitable for solving the formation pore pressure under the condition that the formation has fluid and the formation pressure and the wellbore pressure can maintain a pressure balance.

step S21: gradually increasing the wellhead back pressure, recording the measured riser pressure, annular pressure, wellhead pressure, the flow of the drilling fluid injected into the drilling system and the flow of the drilling fluid discharged from the drilling system in real time, and performing bottom hole leakage judgment by using a working condition identification model based on the measured riser pressure, annular pressure, wellhead pressure, the flow of the drilling fluid injected into the drilling system and the flow of the drilling fluid discharged from the drilling system after the wellhead back pressure is increased every time; if the bottom hole leakage occurs or the wellhead back pressure rises to the highest value required by the well site, the wellhead back pressure is not raised any more; the working condition identification model is a model for judging the working condition based on the pressure of the riser, the pressure of the annulus, the pressure of the wellhead, the flow of the drilling fluid injected into the drilling system and the flow of the drilling fluid discharged from the drilling system; in the process of gradually increasing the wellhead back pressure, the time interval of wellhead back pressure adjustment is not less than the time interval of measurement signal feedback of the annular pressure measurement while drilling tool;

step S22: determining the corresponding bottom hole pressure as the formation fracture pressure based on the riser pressure, the annular pressure and/or the wellhead pressure of the previous time of bottom hole leakage; or; and determining that the back pressure is the bottom hole pressure corresponding to the highest value required by the well site based on the riser pressure, the annular pressure and/or the wellhead pressure after the back pressure is increased to the highest value required by the well site, and further determining that the formation fracture pressure is greater than the bottom hole pressure corresponding to the highest value required by the well site.

If no leakage occurs after the wellhead back pressure is increased to the highest value required by the well site, the pressure resistance of the stratum in the drilling process is considered to be sufficient, and the influence of the leakage stratum is not considered.

Further, the method further comprises:

step S20: before the back pressure of a wellhead is gradually increased, high-density drilling fluid (the drilling fluid with the density higher than that of the original drilling fluid) is injected into a shaft to realize that the bottom hole pressure reaches a preset value; the preset value should be as close as possible to, but not higher than, the formation fracture pressure, and one skilled in the art can make the determination based on the predicted formation fracture pressure;

during the process of injecting the high-density drilling fluid into the shaft, the pressure of the riser, the pressure of the annulus and the pressure of the wellhead can be monitored in real time, and the bottom hole pressure can be regulated and controlled according to an expected numerical value as far as possible;

further, injecting a high density drilling fluid into the wellbore is accomplished by: injecting high-density drilling fluid into the annulus at a certain height, and adjusting the density of the original drilling fluid above an injection point; wherein, the high-density drilling fluid preferably has a density of 0.2g/cm higher than that of the original drilling fluid ³ The drilling fluid of (1);

further, injecting a high density drilling fluid into the wellbore is accomplished by: injecting high-density drilling fluid through the vertical pipe to replace the original drilling fluid in the drilling system; wherein, the high-density drilling fluid preferably has a density of 0.1g/cm higher than that of the original drilling fluid ³ The drilling fluid of (1);

in above-mentioned preferred technical scheme, through dynamic control hydrostatic column pressure back dynamic control well head back pressure, the accurate control of better realization bottom hole pressure, through injecting high density drilling fluid, perhaps inject the annular space high density drilling fluid of a take the altitude into, improvement bottom hole pressure that can be by a relatively large margin, remedy the shortcoming that conventional drilling mode can't or be difficult to survey formation fracture pressure.

ΔP＝ΔρgH

bottom hole pressure changes over time:

In the preferred technical scheme, the bottom hole pressure is finely adjusted by roughly adjusting the bottom hole pressure by changing the density of the drilling fluid once and changing the back pressure of a wellhead for multiple times, so that the determination of the formation fracture pressure can be realized more quickly and conveniently.

Further, in the process of gradually increasing the well mouth back pressure, the pressure increase value of the well mouth back pressure each time is 0.2-1.5 MPa.

Further, in the process of gradually increasing the wellhead back pressure, the pressure increase value of the back pressure of the next wellhead does not exceed the pressure increase value of the back pressure of the previous wellhead; for example, the first wellhead back pressure has a pressure rise of 1.5MPa, and the last wellhead back pressure has a pressure rise of 0.2 MPa.

The bottom hole pressure can be rapidly adjusted by changing the back pressure of the well head, the well head pressure, the riser pressure and the annular pressure (PWD measured value) are mutually influenced, and the bottom hole pressure, the well head pressure, the riser pressure and the annular pressure (PWD measured value) are at a certain timeThe change value of the time interval has certain equivalence, the ground is easy to observe the wellhead back pressure and the riser pressure change, the signal feedback is rapid, the signal feedback is 3-5 minutes later, one of the key factors of downhole complexity such as overflow, leakage and the like is rapidly judged, the annular pressure (PWD measured value) signal feedback is closer to the downhole complex occurrence place, and the main influence factor of downhole complex characteristic analysis is provided. Searching for impossible to put the formation pressure in place in one step, and optimizing the amplitude and the number of pressure adjustments per time, i.e.

ΔP _step，n May be the same or different. In order to test the formation fracture pressure conveniently, a larger pressure adjustment amplitude is set at the initial stage, after the estimated value of the formation pressure is close, a smaller pressure adjustment amplitude is adopted, the minimum value of the pressure adjusted at each step is influenced by the control precision of the wellhead pressure, the highest value is required by the formation pressure test precision, and in the common drilling design, the drilling fluid column pressure and the circulating pressure loss are close to the formation pore pressure and are far away from the formation fracture pressure, so that the wellhead back pressure is increased to be generally 0.2-1.5MPa, and the wellhead back pressure is gradually reduced to 0.2MP from the larger value of 1.5 MPa.

Further, the method further comprises:

step S23: if the bottom hole leakage occurs, the wellhead back pressure is not increased any more, the wellhead back pressure is gradually reduced until the bottom hole leakage disappears, the measured riser pressure, the annular pressure, the wellhead pressure, the flow of the drilling fluid injected into the drilling system and the flow of the drilling fluid discharged from the drilling system are recorded in real time, and after the wellhead back pressure is reduced each time, the bottom hole leakage is judged by utilizing a working condition identification model based on the measured riser pressure, the annular pressure, the wellhead pressure, the flow of the drilling fluid injected into the drilling system and the flow of the drilling fluid discharged from the drilling system;

determining the corresponding bottom hole pressure as a formation fracture pressure verification value based on the riser pressure, the annular pressure and/or the wellhead pressure corresponding to the first no longer occurring bottom hole leakage; correcting the determined formation fracture pressure based on the formation fracture pressure validation value; when the wellhead back pressure is gradually reduced, the time interval of wellhead back pressure adjustment is not less than the time interval of measurement signal feedback of the annular pressure measurement while drilling tool;

P _BHP ＝P _PWD +P _lh +P _hc

in the formula, P _BHP Bottom hole pressure; p is _PWD Is the annulus pressure; p _lh The drilling fluid hydrostatic column pressure below a measuring point for measuring the annular pressure; p is _hc The method comprises the following steps of (1) measuring the annular friction resistance of a borehole below a measuring point of annular pressure;

P _BHP ＝P _PWD +ρ·g·(H _TVD +H _PWD )

in the formula, P _BHP Bottom hole pressure; p _PWD Is the annulus pressure; rho is the drilling fluid density; g is gravity acceleration; h _TVD The bottom hole depth; h _PWD The depth of the measuring point is used for measuring the annular pressure.

P _BHP ＝P _d +P _H -P _{l_in}

in the formula, P _BHP Bottom hole pressure; p _d Is the riser pressure; p _H The hydrostatic column pressure in the drill string port; p _{l_in} The frictional resistance of the drill string water hole.

P _BHP ＝P _h +P _{l_out} +P _back

in the formula, P _BHP Bottom hole pressure; p _h The hydrostatic column pressure of the drilling fluid in the borehole annulus; p _{l_out} The annular friction resistance of the well bore; p _back Is the wellhead pressure.

Furthermore, the working condition identification model is a trained support vector machine working condition identification model, and can realize identification of working conditions in overflow, leakage, overflow and leakage simultaneous storage and overflow and leakage prevention 4.

Further, the determining of bottom hole leakage based on the measured riser pressure, annulus pressure, wellhead pressure, flow of drilling fluid injected into the drilling system and flow of drilling fluid discharged from the drilling system using the condition identification model comprises:

further, the overflow is determined by the following formula:

in the formula: delta Q _Overflow The overflow amount is used; q. q of _in (t) the flow rate of drilling fluid injected into the drilling system; q. q.s _out (t) is the flow rate of drilling fluid discharged from the drilling system; the interval time t2-t1 is not less than one annulus pressure measurement tool while drillingThe interval for feeding back the measurement signal (preferably the interval for feeding back the measurement signal by a primary annular pressure measurement while drilling tool) is provided;

further, the leakage amount is determined by the following formula:

in the formula: delta Q _{Leakage net} Is the leakage amount; q. q.s _in (t) the flow rate of drilling fluid injected into the drilling system; q. q.s _out (t) is the flow rate of drilling fluid discharged from the drilling system; the interval time t2-t1 is not less than the interval time of measurement signal feedback of the measurement-while-drilling tool of the annular pressure (preferably the interval time of measurement signal feedback of the measurement-while-drilling tool of the annular pressure).

Under the normal circulation condition, the flow data of the drilling fluid injected into the drilling system is from the mud pump inlet flowmeter 1, and can also be calculated through the discharge capacity of the mud pump checked by the drilling fluid outlet flowmeter 12; and (4) stopping the operation of the slurry pump, and reading data of an inlet flowmeter 8 of the slurry supplement pump when the ground short circulation control bottom hole pressure is established through the slurry supplement pump. The source of the flow data for the drilling fluid exiting the drilling system is the drilling fluid outlet flow meter 12.

ΔQ＝k·ΔP _BF

the calibration standards for the occurrence of a leak were: the overflow volume is less than a third rated value (should be negative) or the leakage volume is greater than a fourth rated value (should be positive), the column pressure change value, the annular pressure change value and the wellhead pressure change value deviate (in normal working conditions, the three values are equal or close), the annular pressure is continuously and gradually lower or continuously and gradually lower after being temporarily higher compared with the change trend line of the annular pressure under normal working conditions, and the column pressure is gradually lower compared with the change trend line of the column pressure under normal working conditions; as shown in fig. 3A and 3B.

Along with the rising of wellhead back pressure, a PWD measured value also rises gradually, but if leakage occurs, the annular friction resistance is reduced because a part of fluid flows into the stratum in the upper annular space, the annular pressure measured value is gradually reduced when a certain wellhead back pressure value is kept unchanged, because the annular pressure measured value returns with a certain time difference (generally 3-5 minutes), the wellhead back pressure is generally set to be the basic measurement time interval by the annular pressure return interval measured by the PWD, if the stratum has replacement, the fluid with higher pressure enters the shaft, the annular pressure measured value is raised in a short time, but the annular pressure measured value is still turned over and reduced continuously along with the proceeding of leakage and replacement for a long time, the riser pressure is also continuously reduced, and the outflow flow of the drilling fluid return outlet is continuously smaller than the fluid flow pumped by the mud pump, the leakage continues to increase positively or the overflow continues to increase negatively.

Under the condition that drilling flow isoparametric all does not change, drilling fluid hydrostatic column pressure, well bore annular space frictional resistance all can not change, and adjustment well head back pressure control value leads to the change of bottom hole pressure to be: delta P _BHP ＝ΔP _back . Under normal drilling conditions, the distance between an annular pressure measurement while drilling tool (PWD tool) and the bottom of a well is very close, and the length is generally less than 20-30 meters, so that the sum of the hydrostatic column pressure of drilling fluid from a measuring point for measuring the annular pressure to the bottom of the well and the annular friction resistance of a borehole is relatively small, under the conditions of small borehole track adjustment and small drilling fluid discharge change, the change can be approximately considered as no change, and the change value of the bottom-hole pressure is delta P (delta P) which is equal to delta P _PWD . Under the condition that other parameters are not changed, the hydrostatic column pressure in the drill string water hole and the friction resistance of the drill string water hole are not changed, and the change value of the bottom hole pressure is delta P-delta P _BHP ＝ΔP _d . Therefore, if no abnormal working conditions such as underground complexity and the like occur and the spatial attitude of the PWD tool changes obviously, the numerical values are approximately consistent and have equivalence of underground complex judgment, but the signal feedback time is different, the wellhead return pressure changes fastest and the riser pressure is second, but the pressure wave signals (the propagation speed of the pressure wave is 1500-2000m/s in the liquid phase drilling fluid) are mainly transmitted and influenced, the difference is in the second level, the PWD pressure return value is slowest and influenced by the transmission bandwidth of the instrument and the like, the wellhead return pressure value is lagged to change for about 3-5 minutes, but the change of the PWD return pressure value is captured, and the significance is provided for determining whether the bottom of the well overflows or leaks.

P _PWD (t+Δt)＝P _PWD (t)+ρgΔH(Δt)+f(Δl _out (Δt))

in the formula, P _PWD Is the annulus pressure; rho is the drilling fluid density; g is the acceleration of gravity; h _TVD The bottom hole depth; Δ H is the vertical depth of the PWD descent at Δ t time (which is the same as the vertical depth of the drilling at Δ t time); f (Δ l) _out (Δ t)) is the increase in annular friction caused by the depth of PWD run-down/drilling.

P _d (t+Δt)＝P _d (t)+f(Δl _in (Δt))+f(Δl _out (Δt))

The formation pressure while drilling test method provided by the method is suitable for obtaining the formation pore pressure under the condition that the formation has fluid and the formation pressure and the wellbore pressure can maintain a pressure balance.

Example 1

The embodiment provides a formation pressure while drilling testing method, which is performed by using a formation pressure while drilling testing device shown in FIG. 1, and as shown in FIG. 5, the method comprises the following steps:

A. formation pore pressure determination step

A1, reducing the hydrostatic column pressure of the drilling well: injecting low-density drilling fluid into the annulus at a certain height, and adjusting the density of the original drilling fluid above an injection point; the density of the low-density drilling fluid is less than the density of the original drilling fluid by 0.2g/cm ³ ；

In the process of injecting the low-density drilling fluid into a shaft, monitoring the pressure of a riser, the pressure of an annulus and the pressure of a wellhead in real time, and ensuring that the bottom hole pressure is regulated and controlled according to an expected numerical value as far as possible;

a2, reducing wellhead pressure: gradually reducing the back pressure of the wellhead at certain intervals;

gradually reducing wellhead back pressure, recording the measured riser pressure, annular pressure, wellhead pressure, the flow of drilling fluid injected into a drilling system and the flow of drilling fluid discharged from the drilling system in real time, and judging the bottom overflow well by using a working condition identification model based on the measured riser pressure, annular pressure, wellhead pressure, the flow of drilling fluid injected into the drilling system and the flow of drilling fluid discharged from the drilling system after reducing the wellhead back pressure each time; if bottom hole overflow occurs or wellhead back pressure is reduced to 0, wellhead back pressure is not reduced; the working condition identification model is a model for judging the working condition based on the pressure of the riser, the pressure of the annulus, the pressure of the wellhead, the flow of the drilling fluid injected into the drilling system and the flow of the drilling fluid discharged from the drilling system;

in the process of gradually reducing the wellhead back pressure, the time interval of wellhead back pressure adjustment is not less than the time interval of measurement signal feedback of the annular pressure measurement while drilling tool;

wherein, the reduction of the wellhead back pressure can be set at 0.2-0.5MPa, and is gradually reduced to 0.2MPa from a larger value of 0.5 MPa;

a3, calculating the pore pressure of the stratum;

determining corresponding bottom-hole pressure as formation pore pressure based on the riser pressure, the annular pressure and/or the wellhead pressure before bottom-hole overflow occurs; or; determining bottom hole pressure corresponding to the back pressure of 0 based on the riser pressure, the annular pressure and/or the wellhead pressure after the back pressure drop is 0, and further determining that the formation pore pressure is smaller than the bottom hole pressure corresponding to the back pressure of 0; wherein the bottom hole pressure is determined by the following formula:

P _BHP ＝P _PWD +ρ·g·(H _TVD +H _PWD )

B. Formation fracture pressure determination step

B1, raising the drilling hydrostatic column pressure: injecting high-density drilling fluid into the annulus at a certain height, and adjusting the density of the original drilling fluid above an injection point; the density of the high-density drilling fluid is 0.2g/cm higher than that of the original drilling fluid ³ ；

In the process of injecting high-density drilling fluid into a shaft, monitoring the pressure of a riser, the pressure of an annulus and the pressure of a wellhead in real time, and ensuring that the bottom hole pressure is regulated and controlled according to an expected numerical value as far as possible;

b2, raising wellhead pressure: gradually increasing the wellhead back pressure at certain intervals;

gradually increasing the wellhead back pressure, recording the measured riser pressure, annular pressure, wellhead pressure, the flow of the drilling fluid injected into the drilling system and the flow of the drilling fluid discharged from the drilling system in real time, and performing bottom hole leakage judgment by using a working condition identification model based on the measured riser pressure, annular pressure, wellhead pressure, the flow of the drilling fluid injected into the drilling system and the flow of the drilling fluid discharged from the drilling system after the wellhead back pressure is increased each time; if the bottom hole leakage occurs or the wellhead back pressure rises to the highest value required by the well site, the wellhead back pressure is not raised any more; the working condition identification model is a model for judging the working condition based on the pressure of the riser, the pressure of the annulus, the pressure of the wellhead, the flow of the drilling fluid injected into the drilling system and the flow of the drilling fluid discharged from the drilling system;

in the process of gradually increasing the wellhead back pressure, the time interval of wellhead back pressure adjustment is not less than the time interval of measurement signal feedback of the annular pressure measurement while drilling tool;

wherein, the well head back pressure is increased to be 0.2-1.5MPa, and is gradually reduced to 0.2MPa from the larger value of 1.5 MPa;

b3, calculating the fracture pressure of the stratum;

determining the corresponding bottom hole pressure as the formation fracture pressure based on the riser pressure, the annular pressure and/or the wellhead pressure before the bottom hole leakage occurs; or; determining that the back pressure is the bottom hole pressure corresponding to the highest value required by the well site based on the riser pressure, the annular pressure and/or the wellhead pressure after the back pressure is increased to the highest value required by the well site, and further determining that the formation fracture pressure is greater than the bottom hole pressure corresponding to the highest value required by the well site; wherein the bottom hole pressure is determined by the following formula:

P _BHP ＝P _PWD +ρ·g·(H _TVD +H _PWD )

in the formula, P _BHP Bottom hole pressure; p _PWD Is the annulus pressure; ρ isDrilling fluid density; g is the acceleration of gravity; h _TVD The bottom hole depth; h _PWD The measuring point depth for measuring the annular pressure is measured.

The working condition identification model is a trained support vector machine working condition identification model, and can realize identification of working conditions in overflow, leakage, overflow and leakage simultaneous storage and overflow and leakage prevention 4; the trained support vector machine working condition recognition model is determined by the following method:

acquiring historical riser pressure, annular pressure, wellhead pressure, the flow of drilling fluid injected into a drilling system, the flow data of the drilling fluid discharged from the drilling system and working condition marks, and performing [0,1] normalization processing on the historical riser pressure, the annular pressure, the wellhead pressure, the flow of the drilling fluid injected into the drilling system and the flow data of the drilling fluid discharged from the drilling system to obtain a training data set;

training a support vector machine model by utilizing a training data set so as to obtain a trained support vector machine working condition identification model;

the preset support vector machine model is an SVM kernel function type, and a linear kernel function, a polynomial kernel function, a radial basis kernel function or a multilayer perceptron kernel function and the like are selected; as shown in fig. 4, 1, 2, 3, and 4 represent four working conditions of overflow, leakage, overflow and leakage simultaneous storage, and no overflow and leakage respectively; SVM _1-4 (1, 2, 3, 4) represents the initial state, 5 parameters are input. Firstly, obtaining the SVM based on the basic judgment conditions of overflow and no overflow and leakage _1-3 (1, 2, 3) and SVM _2-4 (2,3,4). Then, entering a second layer, and obtaining the SVM based on the judgment condition of overflow and overflow-leakage coexistence _1-2 (1, 2) and SVM _2-3 (2, 3); obtaining the SVM based on the judgment conditions of leakage, no overflow and no leakage _2-3 (2, 3) and SVM _3-4 (3,4). And finally, entering a third layer, and obtaining 1 (overflow) and 2 (leakage) based on overflow and leakage judgment conditions(loss); based on the judgment conditions of leakage and overflow leakage simultaneous storage, 2 (leakage) is determined, and 3 (overflow leakage simultaneous storage) is obtained; based on the judgment conditions of simultaneous leakage and non-leakage, 3 is defined (simultaneous leakage and non-leakage) to obtain 4 (non-leakage and non-leakage).

And when the support vector machine model is trained, a cross validation mode is adopted.

When the trained support vector machine working condition recognition model is used for judging the working condition, the calibration standard of overflow and the calibration standard of leakage are as follows:

the calibration criteria for overflow to occur were: the overflow volume is greater than a first rated value (positive) or the leakage volume is less than a second rated value (negative), the column pressure change value, the annular pressure change value and the wellhead pressure change value deviate (in normal working conditions, the three values are equal or close), the annular pressure continuously and gradually decreases after being temporarily and gradually increased or continuously and gradually decreases after being temporarily and gradually increased compared with the annular pressure change trend line under normal working conditions, and the column pressure gradually decreases compared with the annular pressure change trend line under normal working conditions;

the calibration standards for the occurrence of a leak were: the overflow volume is less than the third rated value (should be negative) or the leakage volume is greater than the fourth rated value (should be positive), the column pressure variation value, the annular pressure variation value and the wellhead pressure variation value deviate (in normal working conditions, the three values are equal or close), the annular pressure continuously and gradually decreases or continuously and gradually decreases after being temporarily higher than the annular pressure variation trend line under normal working conditions, and the column pressure gradually decreases compared with the annular pressure variation trend line under normal working conditions.

Wherein the overflow is determined by the following formula:

in the formula: delta Q _Overflow Is the overflow volume; q. q of _in (t) the flow rate of drilling fluid injected into the drilling system; q. q.s _out (t) is the flow rate of drilling fluid discharged from the drilling system; interval t2-t1 is the primary annular pressureThe interval time for the drill measuring tool to feed back the measuring signal is measured;

the leakage is determined by the following equation:

in the formula: delta Q _{Leakage net} Is the leakage amount; q. q of _in (t) the flow rate of drilling fluid injected into the drilling system; q. q.s _out (t) is the flow rate of drilling fluid discharged from the drilling system; the interval time t2-t1 is the interval time for feeding back the measurement signal of the primary annular pressure measurement while drilling tool;

the first and fourth rated values are 0.1m ³ The second and third nominal values are-0.1 m ³ 。

The preferred embodiments of the present invention have been described above with reference to the accompanying drawings. The many features and advantages of the embodiments are apparent from the detailed specification, and thus, it is intended by the appended claims to cover all such features and advantages of the embodiments which fall within the true spirit and scope thereof. Further, since numerous modifications and changes will readily occur to those skilled in the art, it is not desired to limit the embodiments of the invention to the exact construction and operation illustrated and described, and accordingly, all suitable modifications and equivalents may be resorted to, falling within the scope thereof.

Claims

1. A formation pressure while drilling testing apparatus, wherein the apparatus comprises:

the pressure measurement unit comprises a riser pressure gauge, an annulus pressure measurement while drilling tool and a wellhead pressure gauge; the riser pressure gauge is arranged at the riser manifold; the annular pressure measurement while drilling tool is arranged in the bottom drilling tool assembly and used for measuring annular pressure; the wellhead pressure gauge is arranged on a wellhead return pipeline and used for measuring the pressure of drilling fluid returned from the wellhead;

the pressure control system comprises back pressure control equipment arranged on a well mouth return pipeline and is used for regulating and controlling the back pressure of the well mouth.

2. The apparatus of claim 1, wherein the pumped drilling fluid flow metering device comprises a mud pump inlet flow meter and a mud pump inlet flow meter; the mud pump inlet flowmeter is arranged at an inlet pipeline of a mud pump for supplying liquid to the stand pipe and is used for metering the flow of the drilling liquid pumped into the stand pipe; the inlet flowmeter of the slurry supplement pump is arranged at an inlet pipeline of a slurry supplement pump of a drilling fluid slurry supplement pipeline and is used for measuring the flow of the drilling fluid pumped into the drilling system by the slurry supplement pump; the fluid replacement pipeline refers to a drilling fluid input pipeline used when the drilling fluid in the drilling system establishes ground short circulation.

3. The apparatus of claim 1, wherein the flow metering device comprises a drilling fluid outlet flow meter disposed on a wellhead return line for metering the flow of drilling fluid returned from the wellhead.

4. The apparatus of claim 1, wherein the back pressure control device comprises a first pneumatically controlled flat valve and a self-controlled throttle valve disposed in sequence on a wellhead return line.

5. The apparatus of any of claims 1-4, wherein the formation pressure while drilling testing apparatus further comprises an injection system comprising an injection tube and an injection pressure gauge; the injection pipe is composed of a continuous oil pipe, a preset opening of the wellhead blowout preventer stack extends into the annular space of the shaft for a certain depth, and the injection pressure measuring meter is arranged at the lowest end of the injection pipe and used for measuring the pressure of the injection port.

6. A formation pressure while drilling testing method using the formation pressure while drilling testing apparatus as recited in any one of claims 1 to 5, the method comprising:

gradually reducing wellhead back pressure, recording the measured riser pressure, annular pressure, wellhead pressure, the flow of drilling fluid injected into a drilling system and the flow of drilling fluid discharged from the drilling system in real time, and judging the bottom overflow well by using a working condition identification model based on the measured riser pressure, annular pressure, wellhead pressure, the flow of drilling fluid injected into the drilling system and the flow of drilling fluid discharged from the drilling system after reducing the wellhead back pressure each time; if bottom hole overflow occurs or wellhead back pressure is reduced to 0, wellhead back pressure is not reduced; the working condition identification model is a model for judging the working condition based on the pressure of the riser, the pressure of the annulus, the pressure of the wellhead, the flow of the drilling fluid injected into the drilling system and the flow of the drilling fluid discharged from the drilling system; in the process of gradually reducing the wellhead back pressure, the time interval of wellhead back pressure adjustment is not less than the time interval of measurement signal feedback of the annular pressure measurement while drilling tool;

7. The method of claim 6, wherein the method further comprises: before the back pressure of a wellhead is gradually reduced, low-density drilling fluid is injected into a shaft to achieve that the bottom hole pressure reaches a preset value;

preferably, the injection of the low density drilling fluid into the wellbore is achieved by: injecting low-density drilling fluid into the annulus at a certain height, and adjusting the density of the original drilling fluid above an injection point; the density of the low-density drilling fluid is less than the density of the original drilling fluid by 0.2g/cm ³ ；

More preferably, the injection of the low density drilling fluid into the wellbore is achieved by: injecting low-density drilling fluid through a vertical pipe to replace the original drilling fluid in the drilling system; the density of the low-density drilling fluid is less than the density of the original drilling fluid by 0.1g/cm ³ 。

8. The method according to claim 6, wherein the pressure reduction value of each wellhead back pressure in the process of gradually reducing the wellhead back pressure is 0.2-0.5 MPa.

9. The method of claim 6, wherein the pressure reduction of the subsequent wellhead back pressure during the step-wise reduction of the wellhead back pressure does not exceed the pressure reduction of the previous wellhead back pressure.

10. The method of claim 6, wherein the riser pressure, wellhead pressure measurement interval time is the same as the annulus pressure measurement interval time.

11. The method of claim 6, wherein the method further comprises:

determining the corresponding bottom hole pressure as a formation pore pressure verification value based on the riser pressure, the annular pressure and/or the wellhead pressure corresponding to the first no longer occurring bottom hole overflow; correcting the determined formation pore pressure based on the formation pore pressure verification value; when the wellhead back pressure is gradually increased, the time interval of wellhead back pressure adjustment is not less than the time interval of measurement signal feedback of the annular pressure measurement while drilling tool.

12. The method of claim 6 or 11, wherein making a bottom-hole kick determination using the condition-identifying model based on the measured riser pressure, annulus pressure, wellhead pressure, flow of drilling fluid injected into the drilling system, and flow of drilling fluid drained from the drilling system comprises:

preferably, the amount of overflow is determined by the following formula:

in the formula: delta Q _Overflow Is the overflow volume; q. q.s _in (t) the flow rate of drilling fluid injected into the drilling system; q. q.s _out (t) is the flow rate of drilling fluid discharged from the drilling system; the interval time t2-t1 is not less than the interval time of feeding back the measurement signal by the primary annular pressure measurement while drilling tool;

preferably, the leakage is determined by the following equation:

in the formula: delta Q _{Leakage net} Is the leakage amount; q. q.s _in (t) the flow rate of drilling fluid injected into the drilling system; q. q.s _out (t) is the flow rate of drilling fluid discharged from the drilling system; the interval time t2-t1 is not less than the interval time of measurement signal feedback of the annular pressure measurement-while-drilling tool.

13. The method according to any one of claims 6-12, wherein the operating condition recognition model is a trained support vector machine operating condition recognition model, and can realize recognition of 4 operating conditions of overflow, leakage, overflow and leakage simultaneous storage and no overflow and leakage.

14. The method of claim 13, wherein the trained support vector machine behavior recognition model is determined by:

and carrying out support vector machine model training by using the training data set so as to obtain a trained support vector machine working condition identification model.

15. The method of any of claims 6-12, wherein the bottom hole pressure is determined by the following equation:

P _BHP ＝P _PWD +ρ·g·(H _TVD +H _PWD )

in the formula, P _BHP Bottom hole pressure; p _PWD Is the annulus pressure; rho is the drilling fluid density; g is the acceleration of gravity; h _TVD Is the bottom hole depth; h _PWD The measuring point depth for measuring the annular pressure is measured.

16. A formation pressure while drilling test method is carried out by using the formation pressure while drilling test device, and the method comprises the following steps:

gradually increasing the wellhead back pressure, recording the measured riser pressure, annular pressure, wellhead pressure, the flow of the drilling fluid injected into the drilling system and the flow of the drilling fluid discharged from the drilling system in real time, and performing bottom hole leakage judgment by using a working condition identification model based on the measured riser pressure, annular pressure, wellhead pressure, the flow of the drilling fluid injected into the drilling system and the flow of the drilling fluid discharged from the drilling system after the wellhead back pressure is increased each time; if the bottom hole leakage occurs or the wellhead back pressure rises to the highest value required by the well site, the wellhead back pressure is not raised any more; the working condition identification model is a model for judging the working conditions based on the pressure of the vertical pipe, the pressure of the annulus, the pressure of the wellhead, the flow of the drilling fluid injected into the drilling system and the flow of the drilling fluid discharged from the drilling system; in the process of gradually increasing the wellhead back pressure, the time interval of wellhead back pressure adjustment is not less than the time interval of measurement signal feedback of the primary annular pressure measurement while drilling tool;

determining the corresponding bottom hole pressure as the formation fracture pressure based on the riser pressure, the annular pressure and/or the wellhead pressure before the bottom hole leakage occurs; or; and determining that the back pressure is the bottom hole pressure corresponding to the highest value required by the well site based on the riser pressure, the annular pressure and/or the wellhead pressure after the back pressure is increased to the highest value required by the well site, and further determining that the formation fracture pressure is greater than the bottom hole pressure corresponding to the highest value required by the well site.

17. The method of claim 16, wherein the method further comprises:

before the wellhead back pressure is gradually increased, high-density drilling fluid is injected into a shaft to achieve that the bottom hole pressure reaches a preset value;

preferably, the injection of the high density drilling fluid into the wellbore is achieved by: injecting high-density drilling fluid into the annulus at a certain height, and adjusting the density of the original drilling fluid above an injection point; the density of the high-density drilling fluid is 0.2g/cm higher than that of the original drilling fluid ³ ；

Preferably, the injection of the high density drilling fluid into the wellbore is achieved by: injecting high-density drilling fluid through a vertical pipe to replace the original drilling fluid in the drilling system; the high density drillingThe density of the liquid is 0.1g/cm higher than that of the original drilling fluid ³ 。

18. The method of claim 16, wherein the pressure rise value of each wellhead back pressure during the step-by-step increase of the wellhead back pressure is 0.2-1.5 MPa.

19. The method of claim 16, wherein during the step-up of the wellhead back pressure, the subsequent wellhead back pressure has a pressure increase that does not exceed the previous wellhead back pressure.

20. The method of claim 16, wherein the riser pressure, wellhead pressure measurement interval time is the same as the annulus pressure measurement interval time.

21. The method of claim 16, wherein the method further comprises:

if the bottom hole leakage occurs, the wellhead back pressure is not increased any more, the wellhead back pressure is gradually reduced until the bottom hole leakage disappears, the measured riser pressure, the annular pressure, the wellhead pressure, the flow of the drilling fluid injected into the drilling system and the flow of the drilling fluid discharged from the drilling system are recorded in real time, and after the wellhead back pressure is reduced each time, the bottom hole leakage is judged by utilizing a working condition identification model based on the measured riser pressure, the annular pressure, the wellhead pressure, the flow of the drilling fluid injected into the drilling system and the flow of the drilling fluid discharged from the drilling system;

determining corresponding bottom hole pressure as a stratum fracture pressure verification value based on the riser pressure, the annular pressure and/or the wellhead pressure corresponding to the first no longer occurring bottom hole loss; correcting the determined formation fracture pressure based on the formation fracture pressure validation value; when the wellhead back pressure is gradually reduced, the time interval of wellhead back pressure adjustment is not less than the time interval of measurement signal feedback of the annular pressure measurement while drilling tool.

22. The method of claim 16 or 21, wherein utilizing the regime recognition model for bottom hole loss determination based on the measured riser pressure, annulus pressure, wellhead pressure, flow of drilling fluid injected into the drilling system, and flow of drilling fluid discharged from the drilling system comprises:

determining overflow volume or leakage volume, determining a column pressure change value, determining an annulus pressure change value, determining a wellhead pressure change value and further determining whether bottom hole leakage occurs or not based on the measured riser pressure, annulus pressure, wellhead pressure, the flow of drilling fluid injected into a drilling system and the flow of drilling fluid discharged from the drilling system;

preferably, the amount of overflow is determined by the following formula:

in the formula: delta Q _Overflow Is the overflow volume; q. q of _in (t) the flow rate of drilling fluid injected into the drilling system; q. q.s _out (t) is the flow rate of drilling fluid discharged from the drilling system; the interval time t2-t1 is not less than the interval time of the measurement signal feedback of the primary annular pressure measurement while drilling tool;

preferably, the leakage is determined by the following equation:

in the formula: delta Q _{Leakage net} Is the leakage amount; q. q of _in (t) the flow rate of drilling fluid injected into the drilling system; q. q.s _out (t) is the flow rate of drilling fluid discharged from the drilling system; the interval time t2-t1 is not less than the interval time of measurement signal feedback of the annular pressure measurement-while-drilling tool.

23. The method according to any one of claims 16-22, wherein the condition recognition model is a trained support vector machine condition recognition model, and can realize recognition of conditions in overflow, leakage, overflow and leakage simultaneous storage, and overflow and leakage free 4.

24. The method of claim 23, wherein the trained support vector machine behavior recognition model is determined by:

25. The method of any of claims 16-22, wherein the bottom hole pressure is determined by the equation:

P _BHP ＝P _PWD +ρ·g·(H _TVD +H _PWD )