CN110080739B - Method for judging construction site of vertical well multi-branch fracture - Google Patents

Abstract

The invention relates to the technical field of oil extraction engineering, in particular to a method for judging the construction of a vertical well multi-branch fracture site. The method mainly solves the problem that the conventional method cannot systematically, effectively, quantitatively and accurately judge whether the branch fracture is produced in the vertical well multi-branch fracture site. According to the invention, a journey friction resistance chart and a liquid column pressure chart are established according to the basic construction parameters of the well A and the data of a bottom hole pressure gauge, the net pressure in the well B is calculated in real time by combining the basic construction parameters of the well B, and the corresponding evaluation parameters and judgment method for whether the branch seam is generated on the fracturing site of the well B are provided. The method has the advantages that whether the branch seam is generated on the vertical well multi-branch seam fracturing site or not can be judged accurately, objectively and effectively.

Description

Method for judging construction site of vertical well multi-branch fracture

The technical field is as follows:

the invention relates to the technical field of oil extraction engineering, in particular to a method for judging the construction site of a vertical well multi-branch fracture.

Background art:

in the fracturing process of the multi-branch joint and the temporary plugging diversion fracturing of the vertical well in the oil field, whether the branch joint is generated or not and whether the crack is diverted or not are judged, and the qualitative judgment is simply carried out according to whether the construction pressure rises after the temporary plugging agent is added. The method does not consider the parameters related to the formation of the branch joints and the steering joints, such as net pressure in the joints, horizontal stress difference, rock tensile strength and the like, and cannot accurately, effectively and quantitatively judge whether the branch joints and the steering joints are generated after temporary plugging is added in the fracturing process, so that the multi-branch joint fracturing and temporary plugging steering fracturing field of the vertical well has no specific field construction judgment method.

The invention content is as follows:

the invention aims to provide a method for controlling horizontal stress difference P of a fractured well through comparison_{Difference (D)}Tensile strength P with respect to rock_{Resist against}Sum P_Andnet pressure P in the joint_netThe size of the fracture is determined according to the size of the fracture, and whether the branch fracture is generated or not is determined.

The invention is achieved by the following technical scheme: a vertical well multi-branch fracture site construction judgment method comprises the following steps:

the first step is as follows: after adding the temporary plugging agent, manufacturing a friction drag chart along the way and a fracturing fluid and proppant mixture liquid column pressure chart under the conditions of different sand ratios of the well A; the method comprises the following specific steps:

(1) compiling a well A vertical well multi-branch fracture design;

(2) installing a bottom hole pressure gauge near a sand blaster of a fracturing pipe column of a multi-branch fracture interval of a vertical well of the A well, and putting the fracturing pipe column into a shaft according to a fracturing design;

(3) a pre-liquid stage: the temporary plugging agent is added at a speed V,first, the displacement P_Design-frontConstruction time t_Design-frontCompletely displacing the preset fluid in the shaft into the fracture; then the displacement is 0 and P_Front-1、P_Front-2、P_Front-3……P_Front-n(n is more than or equal to 2) and construction time t_{Front side}(ii) a Finally, completing construction of a pad fluid stage according to a fracturing design;

sand ratio 1 stage: adding temporary plugging agent at speed V, and first adding displacement P_Design-1Construction time t_Design-1Completely displacing the pad fluid in the wellbore into the fracture; then the displacement is 0 and P_1-1、P_1-2、P_1-3……P_1-n(n is not less than 2), each construction time t₁(ii) a Finally, completing construction in the sand ratio 1 stage according to the fracturing design;

……

and (3) sand ratio m stage: adding temporary plugging agent at speed V, and first adding displacement P_Design-mConstruction time t_Design-mCompletely displacing residual fluid in the shaft at the stage of the sand ratio m-1 into the fracture; then the displacement is 0 and P_m-1、P_m-2、P_m-3……P_m-n(n is not less than 2), each construction time t_m(ii) a Finally, completing construction at the m-stage sand ratio (m is more than or equal to 1) according to the fracturing design;

(4) using fracturing design software Fracpro, reading the construction pressure P at each discharge capacity at a pre-fluid stage-sand ratio m stage after adding the temporary plugging agent_{Construction of}Wherein the construction pressure should be read after the liquid is completely displaced into the fracture at the previous stage;

(5) reading the bottom hole pressure P at each discharge rate in the pre-fluid stage-sand ratio m stage after adding the temporary plugging agent from the bottom hole pressure gauge data_DownholeWherein the bottom hole pressure should be read after the fluid has been completely displaced into the fracture at the previous stage;

(6) making a pressure chart of the fracturing fluid and proppant mixture liquid column, wherein when the discharge capacity is 0, the bottom hole pressure P of each construction stage_DownholeMinus construction pressure P_{Construction of}Namely the hydrostatic column pressure P of the mixture of the fracturing fluid and the proppant corresponding to each stage_jyThis value is divided by the fracturing interval depth H_ANamely the pressure P of the fracturing fluid and proppant mixture liquid column under unit depth_yEstablishingFracturing fluid and proppant mixture liquid column pressure P under unit depth of each construction stage_yThe plate which changes with the sand ratio is the pressure plate of the fracturing fluid and proppant mixture liquid column, P_y＝(P_Downhole-P_{Construction of})/H_A＝P_jy/H_A；

(7) Making a friction drag chart board along the way, and constructing the construction pressure P under different construction discharge capacities at each construction stage_{Construction of}Adding the hydrostatic column pressure P of the fracturing fluid and the proppant mixture of the corresponding stage_jyThen subtracting the corresponding bottom hole pressure P_DownholeNamely the on-way friction resistance P corresponding to the depth of the fracturing layer section under different construction discharge capacities in each construction stage_myThis value is divided by the fracturing interval depth H_AI.e. the on-way friction resistance P under the unit depth_mEstablishing the on-way friction resistance P under the unit depth of each construction stage_mThe plate changing with the construction displacement is the on-way friction plate, P_m＝(P_{Construction of}+P_jy-P_Downhole)/H_A＝P_my/H_A；

The second step is that: analyzing the multi-branch seam pressure field result of the vertical well of the well B, and judging whether the well B generates a branch seam; the method comprises the following specific steps:

(1) compiling a multi-branch fracture design of a vertical well of the well B;

(2) calculating the B well closing pressure P_bTesting fracturing according to the fracturing construction characteristics of the block where the B well is located, and calculating the closing pressure P of the B well by using fracturing design software Fracpro_bThen, construction is carried out according to the fracturing design;

(3) calculating the net pressure P in the crack of the well B_net-BIf the inner diameters of the fracturing pipe columns of the well B and the well A are the same, a liquid column pressure chart and a along-the-way friction chart formed by the well A are applied, and the closing pressure P of the well B is combined_bAnd construction pressure P after temporary plugging of well B on site_{Construction of}And fracturing interval depth H_BCalculating the net pressure P in the B well gap in real time_net-BThe calculation formula is as follows: p_net-B＝P_{Construction of}+Py×H_B-P_m×H_B-P_b；

(4) If the well B is subjected to the X-MAC test, counting the well B according to the X-MAC test result of the well BMaximum horizontal principal stress P_{Maximum of-B}Minimum horizontal principal stress P_minimum-BRock tensile strength P_anti-B. Calculating the horizontal main stress difference P of the well B_{Maximum of-B}-P_minimum-BTensile strength P with respect to rock_anti-BSum P_and-B；

If the B well does not carry out the X-MAC test, counting the average value P of the maximum horizontal main stress of the block according to the X-MAC test results of other wells of the B well test block_max-B1Minimum level principal stress mean value P_minimum-B1Average tensile strength of rock P_anti-B1. Calculating the horizontal main stress difference P of the well B_max-B1-P_minimum-B1Tensile strength P with respect to rock_anti-B1Sum P_and-B1；

(5) Comparing and analyzing whether a branch seam is formed; the method comprises the following specific steps:

if the well B is subjected to the X-MAC test, comparing P_and-BAnd P_net-BIf P is the size of_net-B≥P_and-BThen, it means that a branch seam is generated; if P_net-B＜P_and-BIf no branch seam is generated, temporary plugging agent needs to be added again on site, and construction pressure P after the temporary plugging is combined_{Construction of}Recalculating the gap net pressure until P_net-B＞P_and-B；

If well B has not been tested by X-MAC, compare P_and-B1And P_net-BIf P is the size of_net-B≥P_and-B1Then, it means that a branch seam is generated; if P_net-B＜P_and-B1If no branch seam is generated, temporary plugging agent needs to be added again on site, and construction pressure P after the temporary plugging is combined_{Construction of}Recalculating the gap net pressure until P_net-B＞P_and-B1。

Compared with the prior art, the invention has the following beneficial effects:

the invention can systematically, effectively, quantitatively and accurately judge whether the fracturing site generates the turning joint and the branch joint, thereby guiding the dosage optimization of the temporary plugging agent, the single well optimization design and the site construction. Strong controllability, convenient and simple operation, safety and effectiveness.

Description of the drawings:

FIG. 1 is a liquid column pressure chart of a ancient-1 well fracturing fluid and proppant mixture of an embodiment of the present invention;

FIG. 2 is a graph of Gu-1 well edge friction drag in accordance with an embodiment of the present invention.

The specific implementation mode is as follows: the invention will be further explained with reference to the following figures and examples:

the first step is as follows: after adding the temporary plugging agent, manufacturing a friction drag chart along the way and a fracturing fluid and proppant mixture liquid column pressure chart under the conditions of different sand ratios of the ancient-1 well; the method comprises the following specific steps:

(1) compiling an ancient-1 well vertical well multi-branch fracture design;

(2) installing a bottom hole pressure gauge near a sand blaster of a PI2 interval fracturing string of the ancient-1 well, and putting the fracturing string into a shaft according to the fracturing design;

(3) a pre-liquid stage: adding the temporary plugging agent at the speed of 30Kg/min, and firstly adding the temporary plugging agent at the discharge capacity of 3m³The preset liquid in the shaft is completely displaced into the crack in the construction time of 3 min; then the discharge capacity is 0m³/min、0.5m³/min、1.0m³/min、1.5m³/min、2.0m³/min、2.5m³/min、3.0m³/min、3.5m³/min、4.0m³/min、4.5m³/min、5.0m³Min, construction time 30 s; finally, completing construction of a pad fluid stage according to a fracturing design;

10% sand ratio stage: adding the temporary plugging agent at the speed of 30Kg/min, and firstly adding the temporary plugging agent at the discharge capacity of 3m³The preset liquid in the shaft is completely displaced into the crack in the construction time of 3 min; then the discharge capacity is 0m³/min、0.5m³/min、1.0m³/min、1.5m³/min、2.0m³/min、2.5m³/min、3.0m³/min、3.5m³/min、4.0m³/min、4.5m³/min、5.0m³Min, construction time 30 s; finally, completing construction at the 10% sand ratio stage according to the fracturing design;

20% sand ratio stage: adding the temporary plugging agent at the speed of 30Kg/min, and firstly adding the temporary plugging agent at the discharge capacity of 3m³The preset liquid in the shaft is completely displaced into the crack in the construction time of 3 min; then the discharge capacity is 0m³/min、0.5m³/min、1.0m³/min、1.5m³/min、2.0m³/min、2.5m³/min、3.0m³/min、3.5m³/min、4.0m³/min、4.5m³/min、5.0m³Min, construction time 30 s; finally, completing construction at the 20% sand ratio stage according to the fracturing design;

30 percent sand ratio stage: adding the temporary plugging agent at the speed of 30Kg/min, and firstly adding the temporary plugging agent at the discharge capacity of 3m³The preset liquid in the shaft is completely displaced into the crack in the construction time of 3 min; then the discharge capacity is 0m³/min、0.5m³/min、1.0m³/min、1.5m³/min、2.0m³/min、2.5m³/min、3.0m³/min、3.5m³/min、4.0m³/min、4.5m³/min、5.0m³Min, construction time 30 s; finally, completing construction at a 30% sand ratio stage according to a fracturing design;

40% sand ratio stage: adding the temporary plugging agent at the speed of 30Kg/min, and firstly adding the temporary plugging agent at the discharge capacity of 3m³The preset liquid in the shaft is completely displaced into the crack in the construction time of 3 min; then the discharge capacity is 0m³/min、0.5m³/min、1.0m³/min、1.5m³/min、2.0m³/min、2.5m³/min、3.0m³/min、3.5m³/min、4.0m³/min、4.5m³/min、5.0m³Min, construction time 30 s; finally, completing construction at the 40% sand ratio stage according to the fracturing design;

(4) using fracturing design software Fracpro, reading the construction pressure P at each discharge capacity at a pre-fluid stage of-40% sand ratio after adding the temporary plugging agent_{Construction of}See table 1;

(5) reading the bottom hole pressure P at each discharge rate in the pre-fluid stage-sand ratio m stage after adding the temporary plugging agent from the bottom hole pressure gauge data_DownholeSee table 2;

(6) making a pressure chart of the fracturing fluid and proppant mixture liquid column, wherein when the discharge capacity is 0, the bottom hole pressure P of each construction stage_DownholeSubtracting the construction pressure to obtain the hydrostatic column pressure P of the mixture of the fracturing fluid and the proppant at each stage_jyThis value is divided by the fracturing interval depth 2150m is the pressure P of the fracturing fluid and proppant mixture liquid column under the unit depth_yEstablishing the pressure P of the fracturing fluid and the proppant mixture liquid column under the unit depth of each construction stage_yThe plate which changes with the sand ratio is the pressure plate of the fracturing fluid and proppant mixture liquid column;

(7) making a friction drag chart board along the way, and constructing the construction pressure P under different construction discharge capacities at each construction stage_{Construction of}Adding the fracturing fluid and the proppant mixture liquid column pressure P of the corresponding stage_jyThen subtracting the corresponding bottom hole pressure P_DownholeNamely the on-way friction resistance P corresponding to the depth of the fracturing layer section under different construction discharge capacities in each construction stage_myDividing the value by the depth of the fracturing interval 2150m to obtain the on-way friction resistance P under the unit depth_mEstablishing the on-way friction resistance P under the unit depth of each construction stage_mThe plate which changes along with the construction displacement is the on-way friction plate;

the second step is that: analyzing the multi-branch seam pressure field result of the ancient-2 well vertical well, and judging whether the ancient-2 well generates a branch seam or not; the method comprises the following specific steps:

(1) compiling an ancient-2 well vertical well multi-branch fracture design;

(2) calculating the Gu-2 closure pressure P_b-old-2Testing fracturing according to fracturing construction characteristics of a block where the ancient-2 well is located, calculating the closing pressure of the ancient-2 well to be 26MPa by using fracturing design software Fracpro, and then constructing according to fracturing design;

(3) calculating the net pressure P in the ancient-2 well gap_{net-ancient-2}The inner diameters of the ancient-1 well and the ancient-2 well fracturing pipe column are the same, an on-way friction chart version and a liquid column pressure chart version formed by the ancient-1 well are used, the ancient-2 well closing pressure 26MPa, the construction pressure 36.2 after the ancient-2 well is temporarily blocked on site and the fracturing interval depth 2180m are combined, and the net pressure in the ancient-2 well seam is calculated to be 6.2MPa in real time;

(4) and performing an X-MAC test on the ancient-2 well, and counting the maximum horizontal principal stress of 38.8MPa, the minimum horizontal principal stress of 34.7MPa and the rock tensile strength of 1.8MPa of the ancient-2 well according to the X-MAC test result of the ancient-2 well. Calculating the sum P of the horizontal main stress difference of 4.1MPa and the tensile strength of 1.8MPa of rock of the ancient-2 well_and-Gu-2Is 5.9 MPa.

(5) Comparing and analyzing whether a branch seam is formed; the method comprises the following specific steps:

P_and-Gu-2Is 5.9MPa, P_{net-ancient-2}Is 6.2, P_{net-ancient-2}＞P_and-Gu-2Indicating that a branch slit is created.

TABLE 1

TABLE 2

Claims (1)

1. A vertical well multi-branch fracture site construction judgment method is characterized by comprising the following steps: the method comprises the following steps:

the first step is as follows: after adding the temporary plugging agent, manufacturing a friction drag chart along the way and a fracturing fluid and proppant mixture liquid column pressure chart under the conditions of different sand ratios of the well A; the method comprises the following specific steps:

(1) compiling a well A vertical well multi-branch fracture design;

(2) installing a bottom hole pressure gauge near a sand blaster of a fracturing pipe column of a multi-branch fracture interval of a vertical well of the A well, and putting the fracturing pipe column into a shaft according to a fracturing design;

(3) a pre-liquid stage: adding temporary plugging agent at speed V, and first adding displacement P_Design-frontConstruction time t_Design-frontCompletely displacing the preset fluid in the shaft into the fracture; then the displacement is 0 and P_Front-1、P_Front-2、P_Front-3……P_Front-n(n is more than or equal to 2) and construction time t_{Front side}(ii) a Finally, completing construction of a pad fluid stage according to a fracturing design;

sand ratio 1 stage: adding temporary plugging agent at speed V, and first adding displacement P_Design-1Construction time t_Design-1Completely displacing the pad fluid in the wellbore into the fracture; then the displacement is 0 and P_1-1、P_1-2、P_1-3……P_1-n(n is not less than 2), each construction time t₁(ii) a At last according to the fracturingDesigning and finishing the construction of the sand ratio 1 stage;

……

and (3) sand ratio m stage: adding temporary plugging agent at speed V, and first adding displacement P_Design-mConstruction time t_Design-mCompletely displacing residual fluid in the shaft at the stage of the sand ratio m-1 into the fracture; then the displacement is 0 and P_m-1、P_m-2、P_m-3……P_m-n(n is not less than 2), each construction time t_m(ii) a Finally, completing construction at the m-stage sand ratio (m is more than or equal to 1) according to the fracturing design;

(4) using fracturing design software Fracpro, reading the construction pressure P at each discharge capacity at a pre-fluid stage-sand ratio m stage after adding the temporary plugging agent_{Construction of}Wherein the construction pressure should be read after the liquid is completely displaced into the fracture at the previous stage;

(5) reading the bottom hole pressure P at each discharge rate in the pre-fluid stage-sand ratio m stage after adding the temporary plugging agent from the bottom hole pressure gauge data_DownholeWherein the bottom hole pressure should be read after the fluid has been completely displaced into the fracture at the previous stage;

(6) making a pressure chart of the fracturing fluid and proppant mixture liquid column, wherein when the discharge capacity is 0, the bottom hole pressure P of each construction stage_DownholeMinus construction pressure P_{Construction of}Namely the hydrostatic column pressure P of the mixture of the fracturing fluid and the proppant corresponding to each stage_jyThis value is divided by the fracturing interval depth H_ANamely the pressure P of the fracturing fluid and proppant mixture liquid column under unit depth_yEstablishing the pressure P of the fracturing fluid and the proppant mixture liquid column under the unit depth of each construction stage_yThe plate which changes with the sand ratio is the pressure plate of the fracturing fluid and proppant mixture liquid column, P_y＝(P_Downhole-P_{Construction of})/H_A＝P_jy/H_A；

(7) Making a friction drag chart board along the way, and constructing the construction pressure P under different construction discharge capacities at each construction stage_{Construction of}Adding the hydrostatic column pressure P of the fracturing fluid and the proppant mixture of the corresponding stage_jyThen subtracting the corresponding bottom hole pressure P_DownholeNamely the on-way friction resistance P corresponding to the depth of the fracturing layer section under different construction discharge capacities in each construction stage_myThis value is divided by the depth of the fracturing intervalDegree H_AI.e. the on-way friction resistance P under the unit depth_mEstablishing the on-way friction resistance P under the unit depth of each construction stage_mThe plate changing with the construction displacement is the on-way friction plate, P_m＝(P_{Construction of}+P_jy-P_Downhole)/H_A＝P_my/H_A；

The second step is that: analyzing the multi-branch seam pressure field result of the vertical well of the well B, and judging whether the well B generates a branch seam; the method comprises the following specific steps:

(1) compiling a multi-branch fracture design of a vertical well of the well B;

(2) calculating the B well closing pressure P_bTesting fracturing according to the fracturing construction characteristics of the block where the B well is located, and calculating the closing pressure P of the B well by using fracturing design software Fracpro_bThen, construction is carried out according to the fracturing design;

(3) calculating the net pressure P in the crack of the well B_net-BIf the inner diameters of the fracturing pipe columns of the well B and the well A are the same, a liquid column pressure chart and a along-the-way friction chart formed by the well A are applied, and the closing pressure P of the well B is combined_bAnd construction pressure P after temporary plugging of well B on site_{Construction of}And fracturing interval depth H_BCalculating the net pressure P in the B well gap in real time_net-BThe calculation formula is as follows: p_net-B＝P_{Construction of}+Py×H_B-P_m×H_B-P_b；

(4) If the well B is subjected to the X-MAC test, counting the maximum horizontal main stress P of the well B according to the X-MAC test result of the well B_{Maximum of-B}Minimum horizontal principal stress P_minimum-BRock tensile strength P_anti-BCalculating the horizontal main stress difference P of the well B_{Maximum of-B}-P_minimum-BTensile strength P with respect to rock_anti-BSum P_and-B；

If the B well does not carry out the X-MAC test, counting the average value P of the maximum horizontal main stress of the block according to the X-MAC test results of other wells of the B well test block_max-B1Minimum level principal stress mean value P_minimum-B1Average tensile strength of rock P_anti-B1Calculating the horizontal main stress difference P of the well B_max-B1-P_minimum-B1Tensile strength P with respect to rock_anti-B1Sum P_and-B1；

(5) Comparing and analyzing whether a branch seam is formed; the method comprises the following specific steps:

if the well B is subjected to the X-MAC test, comparing P_and-BAnd P_net-BIf P is the size of_net-B≥P_and-BThen, it means that a branch seam is generated; if P_net-B＜P_and-BIf no branch seam is generated, temporary plugging agent needs to be added again on site, and construction pressure P after the temporary plugging is combined_{Construction of}Recalculating the gap net pressure until P_net-B＞P_and-B；

If well B has not been tested by X-MAC, compare P_and-B1And P_net-BIf P is the size of_net-B≥P_and-B1Then, it means that a branch seam is generated; if P_net-B＜P_and-B1If no branch seam is generated, temporary plugging agent needs to be added again on site, and construction pressure P after the temporary plugging is combined_{Construction of}Recalculating the gap net pressure until P_net-B＞P_and-B1。

Images