CN106522928B - Well testing method for unstable pressure drop of well logging head by stopping pump after acidizing and fracturing - Google Patents

Well testing method for unstable pressure drop of well logging head by stopping pump after acidizing and fracturing Download PDF

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CN106522928B
CN106522928B CN201610959184.3A CN201610959184A CN106522928B CN 106522928 B CN106522928 B CN 106522928B CN 201610959184 A CN201610959184 A CN 201610959184A CN 106522928 B CN106522928 B CN 106522928B
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fracturing
acidizing
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pressure drop
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CN106522928A (en
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程汉列
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程汉列
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    • EFIXED CONSTRUCTIONS
    • E21EARTH DRILLING; MINING
    • E21BEARTH DRILLING, e.g. DEEP DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
    • E21B47/00Survey of boreholes or wells
    • E21B47/06Measuring temperature or pressure

Abstract

The invention relates to a well testing method for unstable pressure drop of a pump-stopping well logging port after acidizing and fracturing, which comprises the following steps: (1) recording pressure data of the whole acidizing and fracturing process; (2) recording different fluid displacement data; (3) acquiring a well depth structure and the well diameter of a production interval; (4) acquiring frictional resistance; (5) simulating bottom hole pressure data in the whole process of acidizing and fracturing; (6) obtaining the effective reservoir thickness; (7) obtaining the weighted porosity of the effective reservoir porosity; (8) solving a rock compression coefficient; (9) converting the formation pressure; solving the temperature of the bottom-hole stratum; (10) taking the water saturation; (11) establishing a water injection pressure drop unstable well testing analysis model; (12) obtaining various parameters related to the selection of the analytic model; (13) and obtaining various parameters for evaluating the reservoir. The invention effectively obtains the stratum parameters and evaluates the reservoir. The test cost is saved, the test construction risk is reduced, the single well yield is not influenced, and the dynamic test data recording rate is improved.

Description

Well testing method for unstable pressure drop of well logging head by stopping pump after acidizing and fracturing
Technical Field
The invention belongs to the technical field of petroleum, and relates to a well testing method for unstable pressure drop of a pump-stopping well logging port after acidizing and fracturing.
Background
The existing unstable well testing technology comprises two types:
①, a pressure recovery unstable well test, which is to put a high-precision storage or direct-reading electronic pressure gauge into the bottom of a well by using a steel wire well testing winch or a cable well testing winch after a period of time, to monitor the flowing pressure of a point of the bottom of the well pressure gauge for a certain period of time in the production state of opening the well, then to close the well or to close the well on the ground, to record the pressure recovery data of the point of the bottom of the well pressure gauge after closing the well, and then to analyze the pressure recovery unstable well test by combining the production data of the oil and gas well before closing the well.
②, another is pressure drop unstable well test, putting high precision storage or direct reading type electronic pressure gauge in the well shaft of the water injection well, recording bottom hole pressure for a certain time under the water injection state, then closing the well on the ground or underground, the pressure gauge will record the bottom hole pressure drop data after closing the well, and the pressure drop unstable well test analysis is carried out by combining the injection quantity data during injection.
At present, an unstable well testing test is mainly used for obtaining four parameters of formation pressure, reservoir pollution, seepage capability and boundary condition. For boundary case acquisition, longer shut-in manometry times are often required in hypotonic reservoirs. Under the complex well conditions of high-temperature and high-pressure ultra-deep wells, high-sulfur-content hydrogen sulfide wells and the like, the field pressure measurement process has high requirements on test equipment and great process implementation difficulty, so that the logging of test data of a well test is difficult. And underground accidents (the well entering tool string is blocked and blocked, a steel wire or a cable is broken, and the well entering tool string falls into the well, so that the fish falls into the well) are easy to happen in the construction process, and the later normal production and maintenance are seriously influenced. Meanwhile, the yield is influenced by the recovery of the well closing test pressure, and the test data recording rate is low. And difficulty is brought to acquisition of various stratum parameters and reservoir analysis and evaluation.
The conventional unstable well testing for pressure recovery is to throw a high-precision storage type or direct-reading type electronic pressure gauge into a shaft from a paraffin removal (testing) valve by using a steel wire or a cable in the normal well opening production process of an oil-gas well. Firstly, recording the flowing pressure of a pressure gauge feeding point in the normal process of well production, namely flowing pressure monitoring data. And then closing the well at the well mouth or underground, and recording the pressure recovery process of the logging point after the well is closed by the electronic pressure gauge, namely pressure recovery data. Well testing interpretation software, such as Ecrin, PanSystem and the like, which is mature in the market at present is utilized. The parameters of the well bore radius of the production zone, the density and viscosity of different fluids, the gas-oil ratio in the production process, the effective thickness of the reservoir, the original temperature, the pressure, the formation compression coefficient and the like are input into the software. And leading in the flow pressure monitoring data and the pressure recovery data recorded by the pressure gauge, and leading in the production information of the flow pressure monitoring section in the well-opening production process. And then selecting a pressure recovery section, and selecting a software built-in analytical model to perform fitting analysis on a log-log curve, a semilog curve and a pressure history curve, so that the fitting effect of the log-log curve, the semilog curve and the pressure history curve is good, and various seepage parameters (including wellbore conditions, reservoir conditions and boundary conditions) of the reservoir are obtained.
The existing unstable well testing of pressure recovery has the defects that:
①, before testing, a drifting tool is firstly put into the shaft to perform drifting (the downward penetration depth of the drifting tool string is larger than the preset depth of the testing tool string), so that the shaft is ensured to be unblocked, the testing tool string (with the pressure gauge tool string) can be put into a preset position, and the tool string cannot block or block in the process, so that underground accidents are avoided.
②, the well must be shut in at the surface or downhole to perform a pressure recovery test.
③, a high-precision storage type or direct-reading type electronic pressure gauge must be put into the shaft by using a steel wire or a cable, and the testing process of the testing tool string and the electronic pressure gauge is always kept in the pipe string, and if corrosive fluid is produced in the shaft, the tool string and the electronic pressure gauge are damaged.
④, the test period is long, including the flow pressure monitoring and the pressure recovery monitoring, the whole test takes long time, and the test cost is high.
The conventional pressure drop unstable well testing is that in the normal injection process of water injection well, a high-precision storage type or direct-reading type electronic pressure gauge is put into the well bore from a paraffin removal (testing) valve by using a steel wire or a cable. Firstly, recording pressure data of a measuring point of a bottom hole pressure gauge in the water injection process, namely flowing pressure monitoring data. And then closing the well at the well mouth or underground, and recording the process of measuring point pressure drop after the well is closed by the electronic pressure gauge, namely pressure drop data. Well testing interpretation software, such as Ecrin, PanSystem and the like, which is mature in the market at present is utilized. And (4) carrying out pressure drop instability well testing analysis by combining the injection quantity data during injection. The parameters of the well bore radius of the production zone, the density and viscosity of different fluids, the gas-liquid ratio of injected well bore fluid, the effective thickness of the reservoir, the original temperature and pressure of the reservoir, the formation compression coefficient and the like are input into the software. And the flowing pressure monitoring data and the pressure drop data recorded by the pressure gauge are imported, and the injection quantity information of the flowing pressure monitoring section in the water injection process is imported. And then selecting a pressure drop section, and selecting a built-in analytical model of software to perform fitting analysis on a log-log curve, a semilog curve and a pressure history curve, so that the fitting effect of the log-log curve, the semilog curve and the pressure history curve is good, and various seepage parameters (including wellbore conditions, reservoir conditions and boundary conditions) of the reservoir are obtained.
The existing unstable well testing of pressure drop has the defects that:
①, before testing, a drifting tool is firstly put into the shaft to perform drifting (the downward penetration depth of the drifting tool string is larger than the preset depth of the testing tool string), so that the shaft is ensured to be unblocked, the testing tool string (with the pressure gauge tool string) can be put into a preset position, and the tool string cannot block or block in the process, so that underground accidents are avoided.
②, the test period is long, including the flow pressure monitoring and the pressure drop monitoring, the whole test takes long time, and the test cost is high.
CN201110208804 discloses a pressure drop well testing analysis method for a low permeability reservoir downhole shut-in well water well, but the technical effect of the method for unstable well testing is not ideal.
Disclosure of Invention
In order to overcome the defects of the prior art, the invention provides a well testing method for testing unstable pressure drop of a pumping-stopping well logging port after acidizing and fracturing. The test cost is saved, the test construction risk is reduced, the single well yield is not influenced, and the dynamic test data recording rate is improved.
The invention provides the following technical scheme:
a pressure drop instability testing method for a pump-stopping well logging head after acidizing and fracturing comprises the following steps:
(1) installing an electronic pressure gauge on a wellhead in the acidizing and fracturing process, wherein the electronic pressure gauge is installed on any wellhead device in the acidizing and fracturing process, a pressure gauge sensor of the electronic pressure gauge is connected with any interface capable of receiving the pressure of fluid in a pipe column, and pressure data in the whole acidizing and fracturing process are recorded;
(2) collecting and recording data of different fluid discharge amounts injected into a shaft in the whole process of the acidizing and fracturing by using a flowmeter;
(3) acquiring well depth structure data, tubular column structure data, actual drilling borehole slant depth data and/or actual drilling borehole vertical depth data, and acquiring the well diameter of a production interval;
(4) acquiring physical property characteristics of different fluids injected into a wellbore in the acidizing and fracturing process and frictional resistance of the different fluids under different displacement and different wellbore tubular column structures;
(5) simulating the bottom hole pressure data of the whole acidizing and fracturing process by using the data obtained in the steps (1), (2), (3) and (4) and acidizing and fracturing software;
(6) obtaining the effective reservoir thickness by using the logging information;
(7) obtaining the weighted porosity of the effective reservoir porosity;
(8) solving the rock compression coefficient by using the weighted porosity obtained in the step (7) by adopting an H.N.Hall empirical formula;
(9) measuring the depth of a static liquid level according to the drilling process, and converting the formation pressure; taking reference to adjacent wells, and obtaining the bottom-hole stratum temperature according to the geothermal gradient of the local geological block;
(10) acquiring the water saturation;
(11) transferring the basic parameters obtained in the steps (2), (5), (6), (7), (8), (9) and (10) into well testing analysis software to establish a pressure drop unstable well testing model;
(12) selecting a proper analytical model in software, fitting a log-log curve, a semi-log curve and a pressure history curve in the unstable water injection pressure drop well testing analytical model established in the step (11), achieving good fitting effect, and obtaining various parameters related to the selected analytical model;
(13) and obtaining various parameters for evaluating the reservoir.
In the above scheme, preferably, in the step (1), the pressure data of the whole acidizing and fracturing process includes pressure data of a pump-stopping well-logging pressure reduction process after the acidizing and fracturing construction is completed.
In any of the above aspects, preferably, the electronic manometer is a high-precision high-temperature high-pressure storage or direct-reading electronic manometer. Such as PPS28 quartz storage pressure gauge, PPS series pressure gauge.
The pipe column is a well head acid fracturing well completion pipe column, the fluid in the pipe column is injection liquid in the acid fracturing process, and the injection liquid is acid liquid or fracturing liquid.
In any of the above schemes, preferably, in step (2), the displacement data is injection volume per minute when the wellbore injects fluid.
A wellbore is a string for injecting fluids in an acid fracturing completion string, it being understood that a wellbore is a flowing pipe for an acid fracturing injection fluid.
In any of the above schemes, preferably, in the step (3), the caliper of the production interval is the radius of a drill bit in an open hole section when the production interval is open hole production; when the sleeve or the sieve tube is produced, the inner radius of the sleeve or the sieve tube is the inner radius of the sleeve or the sieve tube; when the oil pipe is produced, the inner radius of the oil pipe is used.
All of the run in string data can be obtained from the field.
In any of the above schemes, preferably, in the step (4), the method for obtaining the frictional resistance is to use acidizing fracturing software to input into the wellbore and the structure of the pipe column in the wellbore to simulate the frictional resistance of different fluids at different discharge rates, or to perform displacement reduction measurement on the site to inject the fluid into the wellbore.
In any of the above embodiments, it is preferable that in step (4), the acid fracturing software is fracprop software, StimPlan software by NS corporation, Terrfrac software by Terra Tek corporation, GOHFER software by Marathon corporation, Mfrac software by Meyer corporation, 3D-HFODS software by southwest oil university, or StimPT software by pininacle corporation. FracpropT software from Pinnace is preferred.
In any of the above embodiments, the fluid property characteristics preferably include fluid composition, density, and viscosity.
In any of the above schemes, preferably, in step (5), the theoretical formula of the simulated bottom-hole pressure during the acidizing fracturing pump injection process is as follows: bottom hole pressure is equal to wellhead pressure, liquid column pressure and friction resistance; when the pressure of the well head is reduced after the pump is stopped: the bottom hole pressure is the wellhead pressure plus the liquid column pressure.
In any of the above aspects, it is preferable that in step (5), the acid fracturing software is FracproPT software, StimPlan software by NS corporation, Terrfrac software by Terra Tek corporation, GOHFER software by Marathon corporation, Mfrac software by Meyer corporation, 3D-HFODS software by southwest oil university, or StimPT software by pininacle corporation. FracpropT software from Pinnace is preferred.
In any of the above schemes, preferably, in step (6), the effective reservoir thickness of the vertical well is: accumulating the vertical thickness of each small effective reservoir layer in the production well section; the effective reservoir thickness of the horizontal well is as follows: and converting the top and bottom slant depth of each small effective reservoir layer in the production well section into vertical depth, and calculating the vertical depth thickness of each small effective reservoir layer and then accumulating.
In any of the above schemes, preferably, in step (6), when there is no test data, the adjacent well is used for comparing values.
In any of the above embodiments, it is preferred that the carbonate oil field has an effective reservoir porosity of greater than 2% and the sandstone oil field has an effective reservoir porosity of greater than 8%.
Well logging methods are well known and are obtained by logging and interpretation. The porosity of effective reservoirs of different types is set differently, and the porosity of the effective reservoir of the carbonate rock of part of the oil fields is more than 2 percent and the porosity of the effective reservoir of the sandstone rock is more than 8 percent. Specifically, the results can be explained by referring to the logging according to different block standards.
The effective reservoir refers to a reservoir which is specified by an oil field, interpreted by logging and is larger than a certain porosity threshold, and the reservoir is called the effective reservoir. In the reservoir below a certain porosity threshold value, because the porosity of the reservoir is too small, little oil and gas resources are in the reservoir, so that the reservoir has no exploitation value, and the extremely small pores cannot produce fluid. But because the reservoir is not continuously developing in the longitudinal direction. The porosity of different small layers is different, and may be a combination of one reservoir + one dry layer + one effective reservoir, and the obtained effective reservoir needs to be weighted according to the thickness thereof to obtain the weighted porosity.
In any of the above schemes, preferably, in step (8), the formula used is an empirical formula of h.n.hall:
wherein, CfIs the rock compression factor.
In the step (8), the adopted formula can also be a Newman formula or a Liangliang formula.
In any of the above schemes, in the step (9), the formation pressure is obtained by using the density or specific gravity of the drilling fluid in the wellbore during the drilling process, and using a formula P ═ ρ × g × h to obtain the static pressure of the fluid column, where h is the height of the hydrostatic column of the drilling fluid during the drilling process, and the temperature is obtained by using the formation temperature of the adjacent wells in the block.
In the step (10), the water saturation is 100% of the near wellbore area water flooding efficiency according to the ideal condition, and other values can be adopted.
In any of the above schemes, preferably, in step (11), the established pressure drop unstable well testing model is a water injection pressure drop unstable well testing analysis or a numerical well testing analysis model.
In any of the above embodiments, the well testing analysis software is preferably PanSystem and Panmesh software of EPS corporation, uk, Saphir software of KAPPA corporation, f.a.s.t.welltest software of Fekete corporation, Welltest200 software of Eclipse corporation, WTSystem software of CUP corporation, MWTWINV3.0 software of western university of petroleum, Swift software of western city line petroleum corporation, or the like.
And when the established model is a numerical well testing analysis model, performing numerical well testing analysis by using the software.
In any of the above aspects, it is preferred that in step (12), the parameters include entries listed as wellbore conditions, formation conditions, and/or boundary conditions.
The invention relates to a method for carrying out pressure drop instability test analysis, which comprises the steps of installing a high-precision high-temperature high-pressure electronic pressure gauge at a well mouth in a single-well acidizing and fracturing process, recording pressure in the acidizing and fracturing process and pressure drop data of a pump-stopping measuring pump after acidizing and fracturing, and combining fluid flow information injected into a shaft in the acidizing and fracturing process. Thereby effectively obtaining stratum parameters and evaluating a reservoir stratum. The test cost is saved, the test construction risk is reduced, the single well yield is not influenced, and the dynamic test data recording rate is improved.
①, the application range of the technical method is not limited to clastic rock reservoirs, and can also be applied to reservoirs such as carbonate rock, ②, the application range of the technical method is not limited to acid fracturing construction, and can also be applied to processes of injecting fluid into the formation to improve the seepage capability of the reservoirs such as acid washing, fracturing, hydraulic fracturing, and the like, ③, the method can be applied to water injection wells, records the pumping pressure at the well head in the water injection process and the pumping pressure drop data after the pump is stopped, and performs the well test with unstable pressure drop of the water injection pump by combining the discharge information in the water injection process.
The invention has the advantages that:
①, no tool string needs to be put into the well bore, and the occurrence of downhole accidents is completely avoided.
②, recording the pressure reduction information of the pump during the acid fracturing process and after the acid fracturing, and stopping the pump to measure the pressure of the pump without influencing the normal production after the operation.
③, the data recording and the acid fracturing construction of the test are carried out simultaneously, and the site construction time is effectively saved.
④, the storage type high-precision electronic pressure gauge is used for recording wellhead pump pressure data in the acidizing and fracturing process, and the test capital cost is greatly saved.
Drawings
FIG. 1 is a DH1-1GH well acid pressure construction curve of a preferred embodiment of a method for testing unstable wellhead pressure drop after acidizing and fracturing;
FIG. 2 is a well depth configuration after testing the DH1-1GH well of the preferred embodiment shown in FIG. 1;
FIG. 3 is a schematic illustration of the preferred embodiment of FIG. 1 showing different displacement of pad fluids in the well string to provide wellbore friction;
FIG. 4 is a schematic illustration of the preferred embodiment of FIG. 1 showing different displacement rates of the bulk acid in the well string for lowering the wellbore friction;
FIG. 5 is a schematic illustration of the preferred embodiment of FIG. 1 showing different displacement rates of clean water in the well string for lowering the well bore friction;
FIG. 6 is a bottom hole pressure simulation of the acidizing fracturing process of the preferred embodiment shown in FIG. 1;
FIG. 7 is an analysis model of acidizing fracturing pump-off pump-logging pressure drop well test of the preferred embodiment shown in FIG. 1;
FIG. 8 is a bi-log curve fit of the acidizing fracturing pump-stop pump-logging pressure drop test well of the preferred embodiment shown in FIG. 1
FIG. 9 is a semi-log curve fit of the acidizing fracturing pump-stop pump-logging pressure drop well test of the preferred embodiment shown in FIG. 1
FIG. 10 is a well pressure history curve fit of the acidizing fracturing pump-stop pump-logging pressure drop test well of the preferred embodiment shown in FIG. 1
FIG. 11 is a semi-log overlay test of acidizing fracturing pump-stop pump-logging pressure drop well test of the preferred embodiment shown in FIG. 1
FIG. 12 is a dual log curve fit of a conventional pressure recovery unstable test well of the preferred embodiment shown in FIG. 1
Fig. 13 is a flow chart of the preferred embodiment shown in fig. 1.
Detailed Description
In order to further understand the technical features of the present invention, the present invention is described in detail with reference to the specific embodiments below. The embodiments are given by way of illustration only and not by way of limitation, and any insubstantial modifications, based on the present disclosure, may be made by those skilled in the art without departing from the scope of the present disclosure.
Example 1:
geology of this example: the selected pressure drop test well is DH1-1GH, the well is the gas injection well, the structure position is the broken anticline zone Donghe No. 1 anticline of the northward uplifted Donghe pond of the Tarismu basin tower, the well completion method is a casing pipe, and the drilling completion layer is the rock-charcoal system Donghe sandstone.
A pressure drop instability testing method for a pump-stopping well logging head after acidizing and fracturing comprises the following steps:
1. in the acidizing and fracturing process, a high-precision high-temperature high-pressure storage or direct-reading electronic pressure gauge is installed at a wellhead, wellhead pressure and casing pressure data are recorded, and the data must contain pumping pressure drop data of a pumping stop logging wellhead. And plotted as an acid fracturing construction graph (figure 1).
2. Collecting and recording data of different fluid discharge amounts injected into a shaft in the whole process of acidizing and fracturing by using a flowmeter; and plotted as an acid fracturing construction graph (figure 1).
3. And constructing a downhole string model according to the well completion depth structure and the well entry string structure, and obtaining the well diameter 0.07854m of the production interval.
4. Example well acidizing fracturing process the fluids injected into the wellbore are: front liquid (dosage is 40 square, density is 1.06 g/cm)3) Main acid (dosage is 100 square),Density 1.06g/cm3) Displacing liquid (dosage is 25 square, clear water is 1.00 g/cm)3) (ii) a Different liquid per kilometer friction is simulated in the present completion string configuration and plotted (fig. 3, 4, 5).
5. And (3) converting the bottom hole pressure data of the whole acidizing and fracturing process by using the data acquired in the steps 1, 2, 3 and 4 (figure 6).
6. And (3) calculating the thickness of an effective reservoir (the porosity of the carbonate rock is more than 2%, the porosity of the sandstone is more than 8%, and the well logging interpretation result can be referred according to different block standards). A vertical well: accumulating the vertical thickness of each small effective reservoir layer in the production well section; horizontal well: and converting the top and bottom slant depth of each small effective reservoir layer in the production well section into vertical depth, and calculating the vertical depth thickness of each small effective reservoir layer and then accumulating. The example well is a horizontal well, and the effective reservoir thickness is 29 m. From the logging results table 1.
TABLE 1 DH1-1GH well logging results
7. A weighted porosity of 16.88% of the available reservoir porosity was found (table 2).
TABLE 2 effective reservoir weighted porosity for DH1-1GH well
Small layer Layer thickness m Porosity% Product of layer thickness and porosity
1 99 16.5 1633.5
2 23 18.8 432.4
3 25 16.5 412.5
4 62 19.5 1209
5 57 14.1 803.7
Summing 266 16.88 4491.1
8. And (4) solving the rock compression coefficient by using the weighted porosity obtained in the step (7) by adopting an H.N.Hall empirical formula. Carry over to obtain CfIs 0.000561704.
9. Measuring the depth of a static liquid level according to the drilling process, and converting the formation pressure of a bottom hole production zone section into 54.19 MPa; and referring to adjacent wells, and obtaining the temperature of the formation at the bottom of the well as 138 ℃ according to the temperature gradient of the local geological block.
10. The water saturation is taken as 100%.
11. And (3) calling the basic parameters obtained in the steps (2), (5), (6), (7), (8), (9) and (10) into an Ecrin software built-in Saphir well testing module for analysis, and establishing a water injection pressure drop unstable well testing analysis model (figure 7).
12. And selecting a pressure drop analysis section in software to obtain a log-log curve, a semi-log curve and a pressure history curve. And selecting a proper analytical model and adjusting relevant parameters for fitting analysis, so that the double logarithmic curve, the semilogarithmic curve and the pressure history curve are well fitted.
The well selection analytic model of the example is as follows: well reservoirs + skin + homogeneous reservoirs + infinite large boundary models, parameters associated with the selected models were adjusted to achieve good fitting of log-log curves, semilog curves, pressure history curves (fig. 8, 9, 10, 11).
Obtaining parameters related to the selection of the analytical model, wherein the parameters comprise: entries listed for wellbore conditions, formation conditions, boundary conditions (table 3).
TABLE 3 DH1-1GH well acidizing fracturing pump-stopping pump-measuring pressure drop well test result parameters
Note: an infinite boundary means that reservoir boundary features are not tested due to insufficient testing time.
13. And obtaining various parameters for evaluating the reservoir (the example well adopts a double logarithm analysis result).
①, the surface coefficient is-4.27, no pollution exists in the near wellbore zone, and the acid fracturing reconstruction effect is good.
②, a flow coefficient of injection fluid 128.95mD · m/mPas, and a general seepage capability.
The pressure drop time of the example well pump stopping is only 20min, and if the test time is prolonged, the double logarithmic curve can more accurately reflect the oil reservoir seepage information and the boundary condition.
2.4 comparing with conventional pressure recovery unstable well testing results
And closing the example well after the production and carrying out a conventional pressure recovery unstable well testing test, wherein the obtained log-log curve form is basically consistent with the log-log curve form obtained by the technical method. Well storage + epidermis + homogeneous reservoir + infinite large boundary model fitting analysis is also selected to obtain a better fitting effect (fig. 12) and obtain related parameters (table 4).
TABLE 4 DH1-1GH well conventional pressure recovery unstable test well outcome parameters
Note: an infinite boundary means that reservoir boundary features are not tested due to insufficient testing time.
And (4) comparing and concluding:
①, the shape of the log-log curve obtained by the two evaluation methods is basically consistent, the selected consistent analytical model can well fit the log-log curve, the semilog curve and the pressure history curve, and the skin coefficients obtained by the two methods are basically consistent and the flow coefficient values of different fluids in the stratum are basically consistent.
②, the pump-stopping pressure drop time is prolonged, the double-logarithmic curve can more accurately reflect the oil reservoir seepage information and boundary conditions, and the parameters obtained by fitting analysis can be more accurate.
③, performing pump-stopping pump-measuring pump pressure drop unstable well testing analysis on the well after acidizing and fracturing, wherein the obtained result parameters can be primarily used for evaluating the seepage characteristics of the reservoir and providing guidance basis for the next step of measures (including secondary acidizing and fracturing modification, hole filling and layer changing, pressure recovery unstable well testing and the like).
2.5 the technical scheme of the embodiment brings about beneficial effects
The method avoids the risk of underground operation, strengthens the number of dynamic test data logging wells, does not influence the normal production of the test wells after the test wells are put into operation, saves the field construction time and greatly saves the test capital cost.
①, no tool string needs to be put into the well bore, and the occurrence of downhole accidents is completely avoided.
②, can be applied to any well condition, including high temperature, high pressure, high hydrogen sulfide content, etc. the method greatly increases the recording of single well dynamic test data, and is helpful for guiding later measures and production development.
③, recording the pressure reduction information of the pump during the acid fracturing process and after the acid fracturing, and stopping the pump to measure the pressure of the pump without influencing the normal production after the operation.
④, the data recording and the acid fracturing construction of the test are carried out simultaneously, and the site construction time is effectively saved.
⑤, the storage type high-precision electronic pressure gauge is used for recording wellhead pump pressure data in the acidizing and fracturing process, and the test capital cost is greatly saved.

Claims (9)

1. A pressure drop instability testing method for a pump-stopping well logging head after acidizing and fracturing comprises the following steps:
(1) installing an electronic pressure gauge on a wellhead in the acidizing and fracturing process, wherein the electronic pressure gauge is installed on any wellhead device in the acidizing and fracturing process, a pressure gauge sensor of the electronic pressure gauge is connected with any interface capable of receiving the pressure of fluid in a pipe column, pressure data in the whole acidizing and fracturing process are recorded, the pipe column is a wellhead acid fracturing well completion pipe column, the fluid in the pipe column is injection fluid in the acid fracturing process, and the injection fluid is acid fluid or fracturing fluid; the pressure data of the whole acidizing and fracturing process comprises pressure data of a pump-stopping well logging pressure reduction process after acidizing and fracturing construction is completed;
(2) collecting and recording data of different fluid discharge amounts injected into a shaft in the whole process of the acidizing and fracturing by using a flowmeter;
(3) acquiring well depth structure data, tubular column structure data, actual drilling borehole slant depth data and/or actual drilling borehole vertical depth data, and acquiring the well diameter of a production interval;
(4) acquiring physical property characteristics of different fluids injected into a wellbore in the acidizing and fracturing process and frictional resistance of the different fluids under different displacement and different wellbore tubular column structures;
(5) simulating the bottom hole pressure data of the whole acidizing and fracturing process by using the data obtained in the steps (1), (2), (3) and (4) and acidizing and fracturing software;
(6) obtaining the effective reservoir thickness by using the logging information;
(7) obtaining the weighted porosity of the effective reservoir porosity;
(8) solving a rock compression coefficient by using the weighted porosity obtained in the step (7) through a formula;
(9) measuring the depth of a static liquid level according to the drilling process, and converting the formation pressure; taking reference to adjacent wells, and obtaining the bottom-hole stratum temperature according to the geothermal gradient of the local geological block;
(10) acquiring the water saturation;
(11) transferring the basic parameters obtained in the steps (2), (5), (6), (7), (8), (9) and (10) into well testing analysis software to establish a pressure drop unstable well testing model;
(12) selecting a proper analytical model in well testing analysis software, fitting a log-log curve, a semi-log curve and a pressure history curve in the pressure drop unstable well testing model established in the step (11), achieving good fitting effect, and obtaining various parameters related to the selected analytical model;
(13) and obtaining various parameters for evaluating the reservoir.
2. The well testing method for testing unstable wellhead pressure drop by pump shutdown after acidizing and fracturing, which is characterized in that: in the step (3), the well diameter of the production interval is the radius of a drill bit of an open hole section when the production interval is produced by the open hole; when the sleeve or the sieve tube is produced, the inner radius of the sleeve or the sieve tube is the inner radius of the sleeve or the sieve tube; when the oil pipe is produced, the inner radius of the oil pipe is used.
3. The well testing method for testing unstable wellhead pressure drop by pump shutdown after acidizing and fracturing, which is characterized in that: in the step (4), the friction resistance is obtained by inputting acidizing fracturing software into the shaft and the pipe column structure in the shaft to simulate the friction resistance of different fluids under different discharge capacities, or by performing discharge reduction measurement on the site to measure the friction resistance of the fluid injected into the shaft.
4. The well testing method for testing unstable wellhead pressure drop by pump shutdown after acidizing and fracturing, which is characterized in that: in the step (5), the acid fracturing software is FracpropT software, Stimplan software, T Terrfrac software, GOHFER software, Mfrac software, 3D-HFODS software or StimPT software.
5. The well testing method for testing unstable wellhead pressure drop by pump shutdown after acidizing and fracturing, which is characterized in that: in the step (6), the effective reservoir thickness of the vertical well is as follows: accumulating the vertical thickness of each small effective reservoir layer in the production well section; the effective reservoir thickness of the horizontal well is as follows: and converting the top and bottom slant depth of each small effective reservoir layer in the production well section into vertical depth, and calculating the vertical depth thickness of each small effective reservoir layer and then accumulating.
6. The well testing method for testing unstable wellhead pressure drop by pump shutdown after acidizing and fracturing, which is characterized in that: in the step (8), the formula adopted is an empirical formula of H.N.Hall:
wherein the content of the first and second substances,C f is composed ofThe compression coefficient of the rock.
7. The well testing method for testing unstable wellhead pressure drop by pump shutdown after acidizing and fracturing, which is characterized in that: in the step (9), the formation pressure is obtained by using the density or specific gravity of the drilling fluid in the shaft during the drilling process, and the formula P = ρ × g × h to obtain the static pressure of the fluid column, where h is the height of the hydrostatic column of the drilling fluid during the drilling process, and the temperature is obtained by using the formation temperature of the adjacent wells in the block.
8. The well testing method for testing unstable wellhead pressure drop by pump shutdown after acidizing and fracturing, which is characterized in that: in the step (11), the established model is a water injection pressure drop unstable well testing analysis or numerical well testing analysis model.
9. The well testing method for testing unstable wellhead pressure drop by pump shutdown after acidizing and fracturing, which is characterized in that: in step (12), the parameters include entries listed as wellbore conditions, formation conditions, and/or boundary conditions.
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