CN116859021A - Method for evaluating reservoir sensitivity through productivity damage rate - Google Patents
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- 230000006378 damage Effects 0.000 title claims abstract description 70
- 230000035945 sensitivity Effects 0.000 title claims abstract description 69
- 238000000034 method Methods 0.000 title claims abstract description 33
- 230000035699 permeability Effects 0.000 claims abstract description 128
- 238000002347 injection Methods 0.000 claims abstract description 81
- 239000007924 injection Substances 0.000 claims abstract description 81
- 238000004519 manufacturing process Methods 0.000 claims abstract description 44
- 230000014759 maintenance of location Effects 0.000 claims abstract description 40
- 238000002474 experimental method Methods 0.000 claims abstract description 34
- 208000027418 Wounds and injury Diseases 0.000 claims abstract description 28
- 239000012530 fluid Substances 0.000 claims abstract description 28
- 208000014674 injury Diseases 0.000 claims abstract description 28
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 25
- 239000002253 acid Substances 0.000 claims description 16
- 239000011159 matrix material Substances 0.000 claims description 16
- 239000003513 alkali Substances 0.000 claims description 10
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- 238000004364 calculation method Methods 0.000 claims description 7
- 230000008569 process Effects 0.000 claims description 7
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- 230000009286 beneficial effect Effects 0.000 abstract description 3
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- 239000011148 porous material Substances 0.000 description 15
- WCUXLLCKKVVCTQ-UHFFFAOYSA-M Potassium chloride Chemical compound [Cl-].[K+] WCUXLLCKKVVCTQ-UHFFFAOYSA-M 0.000 description 10
- 239000011435 rock Substances 0.000 description 10
- 230000033558 biomineral tissue development Effects 0.000 description 9
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- 238000004458 analytical method Methods 0.000 description 6
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- HPALAKNZSZLMCH-UHFFFAOYSA-M sodium;chloride;hydrate Chemical compound O.[Na+].[Cl-] HPALAKNZSZLMCH-UHFFFAOYSA-M 0.000 description 6
- 239000000243 solution Substances 0.000 description 6
- BVKZGUZCCUSVTD-UHFFFAOYSA-L Carbonate Chemical compound [O-]C([O-])=O BVKZGUZCCUSVTD-UHFFFAOYSA-L 0.000 description 5
- 239000001103 potassium chloride Substances 0.000 description 5
- 235000011164 potassium chloride Nutrition 0.000 description 5
- 238000004088 simulation Methods 0.000 description 5
- 230000018109 developmental process Effects 0.000 description 4
- 239000012153 distilled water Substances 0.000 description 4
- 238000009738 saturating Methods 0.000 description 4
- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical compound [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 description 3
- 238000010306 acid treatment Methods 0.000 description 3
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- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 description 2
- 239000012670 alkaline solution Substances 0.000 description 2
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- KKCBUQHMOMHUOY-UHFFFAOYSA-N sodium oxide Chemical compound [O-2].[Na+].[Na+] KKCBUQHMOMHUOY-UHFFFAOYSA-N 0.000 description 2
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
- Y02A10/00—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE at coastal zones; at river basins
- Y02A10/40—Controlling or monitoring, e.g. of flood or hurricane; Forecasting, e.g. risk assessment or mapping
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Abstract
The invention discloses a method for evaluating reservoir sensitivity through productivity damage rate, which comprises the following steps: taking a core on the site of a target block, carrying out a sensitivity injury experiment on the core of the target block, drawing a permeability retention rate and injection volume multiple curve after sensitivity injury, and fitting a relation between the permeability retention rate and the injection volume multiple; according to geological data such as logging, a three-dimensional geological model is established for the target block, and the geological model is corrected; simulating a production process by using the initial permeability of the stratum, and recording the ideal productivity of the production well; simulating the production process again based on the corrected three-dimensional geological model; and (3) calculating the productivity damage rate of the reservoir stratum by comparing the productivity of the external fluid under different injection amounts with the ideal productivity of the reservoir stratum without sensitivity damage, and taking the productivity damage rate as an evaluation index of the reservoir stratum sensitivity. The invention has the advantages of safe experiment, simple operation, economy, effectiveness and the like; and the method is beneficial to accurately evaluating the reservoir, and improving the oil gas productivity and the economic benefit of oil and gas field development.
Description
Technical Field
The invention relates to a method for evaluating reservoir sensitivity through productivity damage rate, and belongs to the field of petroleum gas field development.
Background
In different stages of oil and gas field development, reservoirs can be contacted with different external fluids, various physical and chemical reactions occur, and the oil and gas flowing capacity in the reservoirs is reduced, so that the production capacity of the reservoirs is damaged to different degrees. The method can accurately evaluate the sensitivity of the reservoir and analyze the damage mechanism of the reservoir, and can provide important reference basis for the preparation of the oil and gas production process scheme. The understanding of the sensitivity of the reservoir is deepened, the reservoir damage can be prevented in each construction link, the reservoir productivity is fully exerted, and the purpose of scientifically developing the oil-gas field is achieved.
The conventional reservoir sensitivity evaluation method is not accurate for evaluating the actual damage of the oil and gas reservoir, and because seepage of fluid in the reservoir is non-uniform, the actual sweep range and sweep degree are limited, and the overall damage to the whole reservoir is not caused, the reservoir sensitivity evaluation method considering the non-uniform damage of the reservoir needs to be provided.
Disclosure of Invention
In order to overcome the problems in the prior art, the present invention provides a method for evaluating reservoir sensitivity by capacity impairment rate.
The technical scheme provided by the invention for solving the technical problems is as follows: a method for evaluating reservoir sensitivity by productivity impairment rate, comprising the steps of:
firstly, taking a core on a target block site, carrying out sensitive injury experiments with different injection multiples on the core of the target block, and determining permeability retention rate after sensitive injury;
drawing a curve of permeability retention rate and injection volume multiple after the sensitive injury, and fitting a relation between permeability retention rate and injection volume multiple after the sensitive injury;
step three, a three-dimensional geological model is established for the target block according to geological data, and the production process is simulated by using the initial permeability of the stratum to obtain the flowing PV number of the matrix grid; obtaining the permeability of each matrix grid corresponding to different injection volume multiples according to the relation between the permeability retention rate and the injection volume multiples after the sensitive damage by the obtained flow PV number corresponding to each matrix grid, obtaining the permeability of all matrix grids of the target area, and correcting the three-dimensional geological model;
simulating a production process based on a three-dimensional geological model to obtain ideal productivity of a production well; simulating the production process again based on the corrected three-dimensional geological model to obtain the simulated productivity of the production well;
and fifthly, obtaining the damage rate of the productivity of the reservoir according to the ideal productivity of the production well and the simulated productivity of the production well, and evaluating the sensitivity of the reservoir of the production well according to the damage rate of the productivity of the reservoir.
The further technical scheme is that the sensitive injury experiment in the first step comprises quick-sensitive, water-sensitive, salt-sensitive, acid-sensitive and alkali-sensitive injury experiments.
The further technical scheme is that the relation between the permeability retention rate and the injection volume multiple after the sensitive injury in the second step is as follows:
wherein: k (K) n Core permeability under different injection volume multiples for a certain sensitivity experiment; k (K) i Initial permeability for the core; PV is the injection volume multiple.
The technical scheme is that the specific process of the third step is as follows:
step 31, a three-dimensional geological model is established for the target block according to geological data, wherein the three-dimensional geological model is a three-dimensional grid body, the established reservoir grid data model represents the flow distribution rule of reservoir fluid, and each grid has a series of attributes;
step 32, inputting initial permeability into a three-dimensional geological model, wherein the set T= {1,2,3, …, T, …, m } represents a time step sequence, T represents a time step, and m represents a final time step; making each time step represent the injection amount of the external fluid injected by the injection well in the time step, and obtaining the PV number of each matrix grid in each time step t when the external fluid is injected;
step 33, calculating to obtain the permeability of the first grid corresponding to the first time step according to the PV number corresponding to the first grid of the first time step;
step 34, repeating the previous step, and obtaining the permeability of the second grid in the first time step until the calculation of the permeability of the last grid is finished, so as to obtain a permeability set of all grids in the first time step;
step 35, repeating step 33 and step 34 until the m-th time step is simulated, wherein each time step can obtain the permeability set of all grids of the time step;
and 36, inputting the permeability set into all grids of the geological model, and correcting the grid data to obtain a corrected three-dimensional geological model.
The further technical scheme is that the calculation formula of the reservoir productivity damage rate in the step five is as follows:
wherein: j is the productivity damage rate; p (P) t The productivity under different injection amounts is achieved; p (P) i Ideal productivity at different injection volumes.
In the fifth step, when the damage rate J of the reservoir capacity is less than or equal to 5%, the reservoir sensitivity is evaluated as weak;
when the damage rate of the productivity of the reservoir is 5 percent and J is less than or equal to 10 percent, the sensitivity of the reservoir is evaluated as strong;
reservoir sensitivity was evaluated as adjusting the construction schedule when the reservoir capacity damage rate J > 10%.
The invention has the following beneficial effects: the invention has the advantages of safe experiment, simple operation, economy, effectiveness and the like; and the method is beneficial to accurately evaluating the reservoir, and improving the oil gas productivity and the economic benefit of oil and gas field development.
Drawings
FIG. 1 is a graph showing permeability retention and injection volume multiple relationship for a subject zone for a sensitivity experiment;
FIG. 2 is a graph of an X oilfield core water sensitivity experiment;
FIG. 3 is a graph showing the simulated productivity versus the actual productivity of two methods.
Detailed Description
The following description of the embodiments of the present invention will be made apparent and fully in view of the accompanying drawings, in which some, but not all embodiments of the invention are shown. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
The invention discloses a method for evaluating reservoir sensitivity through capacity injury rate, which comprises the following steps:
firstly, taking a core on a target block site, carrying out sensitive injury experiments with different injection multiples on the core of the target block, and determining permeability retention rate after sensitive injury; drawing a curve of permeability retention rate and injection volume multiple after the sensitive injury, and fitting a relation between permeability retention rate and injection volume multiple after the sensitive injury;
wherein the specific susceptibility injury experiments are as follows:
firstly, taking a core of a target block, cutting a core of a target reservoir with the diameter of about 2.5cm and the length of 4-7cm according to a SYT5358-2010 core preparation method, drying at 60 ℃ to constant weight, and measuring the length, diameter and porosity of the core; and checking the air tightness of the device, wherein the monitoring time is not less than 48 hours.
Then, carrying out a sensitivity injury experiment on the core of the target block:
(1) The rapid sensitivity injury experiment sequentially comprises the following steps:
(1) under the condition of room temperature, the simulated formation water is preparedThen using simulated formation water to saturate the core, placing the core holder into the core, slowly regulating confining pressure to 2MPa, using simulated formation water to displace the core, and measuring initial permeability K of the core i . And (3) calculating the initial permeability of the core according to a formula (1), and calculating the pore volume of the core according to a formula (2).
Wherein: k (K) i The initial permeability (core permeability corresponding to simulated formation water in experiments); q is the displacement speed; p (P) in Pressure at the inlet end of the core holder; p (P) out For core holder outlet end pressure
Wherein: vp is core pore volume; d is the diameter of the core; l is the length of the core;is the core porosity;
(2) 0.10cm as defined with reference to SYT5358-2010 3 /min、0.25cm 3 /min、0.50cm 3 /min、0.75cm 3 /min、1.0cm 3 /min、1.5cm 3 /min、2.0cm 3 /min、3.0cm 3 /min、4.0cm 3 /min、5.0cm 3 /min and 6.0cm 3 And (3) carrying out experiments on the flow per min, stopping after 15 times of core pore volume (PV for short) is displaced, and measuring the permeability of each fixed PV number under the corresponding flow rate, wherein the specific displacement times, the fixed PV number and the experimental flow rate can be determined according to the core condition.
(3) And measuring pressure, flow, time and temperature according to requirements, and recording detection data after the flowing state tends to be stable.
(4) And (3) data processing: the rate-sensitive permeability retention is calculated according to equation (3).
Wherein: d (D) vn Core permeability retention rates corresponding to different injection volume multiples; k (K) vn Core permeability (core permeability corresponding to different injection volume multiples at different flow rates in experiments); k (K) i Is the initial permeability;
(5) analysis of experimental results: at 0.10cm 3 /min、0.25cm 3 /min、0.50cm 3 /min、0.75cm 3 /min、1.0cm 3 /min、1.5cm 3 /min、2.0cm 3 /min、3.0cm 3 /min、4.0cm 3 /min、5.0cm 3 /min and 6.0cm 3 And (3) carrying out displacement experiments at the flow rate of/min, wherein the cumulative injection volume multiple of the formation water is an abscissa, the core permeability retention rate corresponding to different injection volume multiples is an ordinate, and drawing a speed sensitivity evaluation experiment curve.
(2) The water-sensitive injury experiment sequentially comprises the following steps:
(1) preparing simulated formation water at room temperature, then saturating the core with the simulated formation water, placing the core into a core holder, slowly adjusting the confining pressure to 2MPa, displacing the core with the simulated formation water, and measuring the initial permeability K of the core i . And (3) calculating the initial permeability of the core according to a formula (1), and calculating the pore volume of the core according to a formula (2).
(2) And then, displacing the core by using distilled water, stopping after displacing 15 times of core pore volume (PV for short), wherein the specific displacement times and the fixed PV number can be determined according to the core condition, and measuring the permeability of the core with the fixed PV number by using distilled water.
(3) And (3) data processing: the water sensitive permeability retention is calculated according to equation (4).
Wherein: d (D) wn Is water-sensitive permeability retention; k (K) wn The permeability corresponding to distilled water in a water sensitivity experiment; k (K) i Is the initial permeability of the core (the rock corresponding to simulated formation water)Heart rate);
(4) analysis of experimental results: and drawing a water sensitivity evaluation experimental curve by taking the cumulative injection volume multiple of distilled water as an abscissa and taking the core permeability retention rate corresponding to different injection volume multiples as an ordinate.
(3) The salt-sensitive injury experiment sequentially comprises the following steps:
(1) preparing simulated formation water at room temperature, then saturating the core with the simulated formation water, placing the core into a core holder, slowly adjusting the confining pressure to 2MPa, displacing the core with the simulated formation water, and measuring the initial permeability K of the core i . And (3) calculating the initial permeability of the core according to a formula (1), and calculating the pore volume of the core according to a formula (2).
(2) Then, the mineralization of the experimental fluid is reasonably set according to the specific condition of the mineralization of the stratum fluid, the pore volume of the displacement core is 15 times, the displacement is stopped, and the specific displacement multiple and the fixed PV number can be determined according to the core condition. Keeping the confining pressure and the temperature unchanged, and measuring the permeability of the core with the same mineralization degree by using the saline water.
(3) And carrying out displacement tests of different mineralization degrees by the same method until the test of the mineralization degree of 0 is finished, and respectively measuring the core permeability.
(4) Data processing, core permeability retention rate of different injection volume multiples caused by salinity change:
wherein: d (D) sn Core permeability retention rates corresponding to different injection volume multiples; k (K) sn Core permeability (core permeability corresponding to different injection volume multiples under saline with different mineralization degrees in experiments); k (K) i Is the initial permeability (core permeability corresponding to the initial fluid);
(5) analysis of experimental results: and drawing a salinity sensitivity evaluation experimental curve by taking the cumulative injection volume multiple of the series of saline as an abscissa and the core permeability retention rate corresponding to different injection volume multiples as an ordinate.
(4) The acid-sensitive injury experiment sequentially comprises the following steps:
(1) acid liquor selection: no special requirement is met, and 15% HCI or 12HCI+3% HF can be selected; the carbonate reservoir was tested directly with 15% hci. Acid formulation was performed with reference to SYT5358-2010 for acid sensitivity evaluation experiments on sandstone reservoirs with specific requirements.
(2) Back pressure selection: selecting a rock core with higher carbonate content, wherein the back pressure can be determined according to the actual condition of the oil reservoir and CO 2 The solubility of the gas under different pressure and temperature conditions is selected.
(3) The liquid permeability before the rock core acid treatment is measured by displacement with a potassium chloride solution of the same mineralization degree as the stratum water. And (3) calculating the initial permeability of the core according to a formula (1), and calculating the pore volume of the core according to a formula (2).
(4) The sandstone sample is reversely injected with 15 times of pore volume acid liquor, the carbonate sample is reversely injected with 15 times of pore volume 15% HCl, and the carbonate sample is displaced at 0.8 times of critical flow rate. Stopping displacement, closing the inlet and outlet valves of the clamp, and reacting sandstone with acid for 1h and reacting carbonate with acid for 0.5h. And (3) forward displacement of potassium chloride solution with the same mineralization degree as the stratum water after acid rock reaction, and measuring the liquid permeability of the rock core after acid treatment per fixed PV number. The specific displacement times and fixed PV numbers may depend on the core case.
(5) Acid sensitive permeability retention:
wherein: d (D) acn Retention for acid sensitive permeability; k (K) i The initial permeability (core permeability corresponding to the experimental fluid before acid treatment); k (K) acn The core permeability corresponding to the acid liquid treated with different injection volume multiples is obtained;
(6) analysis of experimental results: and drawing an acid sensitivity evaluation experimental curve by taking cumulative injection volume multiples of the acid liquor as an abscissa and taking core liquid permeability retention rates before and after acid liquor treatment with different injection volume multiples as an ordinate.
(5) The alkali-sensitive injury experiment sequentially comprises the following steps:
(1) preparing potassium chloride brine with the same mineralization degree as the stratum water as injection water; then, dilute sodium oxide or dilute hydrochloric acid solution is used for adjusting the pH value of the potassium chloride brine to be between 6 and 7 (called initial brine); then saturating the core with the initial brine; the core was then displaced with the initial brine at a critical flow rate of 0.8 times the experimental flow rate, and the permeability of the core was measured. And (3) calculating the initial permeability of the core according to a formula (1), and calculating the pore volume of the core according to a formula (2).
(2) Secondly, the pH value of the potassium chloride brine is regulated by dilute sodium oxide solution, so that the pH value of the alkali liquor is continuously increased at 1-1.5 pH value unit intervals, and each 1-1.5 pH values are an experimental point.
(3) The next step is to inject the alkaline solution with the adjusted pH value into the core to displace 15 times of the core pore volume, and the specific injection times and the fixed PV number can be determined according to the core condition. Stopping displacement, and enabling the alkali liquor to react with the rock minerals for more than 12 hours; finally, the same method was used to measure the permeability of the core per fixed PV number by injecting the alkaline solution into the core.
(4) The pH value sequence of alkali liquor injection is carried out from low to high, and the experimental flow rate is kept consistent in the experimental process. The above procedure was repeated until the pH reached 13 and stopped.
(5) And (3) data processing:
the permeability retention for different injection volume multiples due to pH changes was calculated as in equation (7).
Wherein: d (D) aln Core permeability retention rate corresponding to alkali liquor with different pH values; k (K) aln The core liquid permeability (core permeability corresponding to different injection volume multiples under alkali lye with different pH values); k (K) i The initial permeability of the rock core (the rock core liquid permeability corresponding to the initial pH value alkali liquor in the experiment);
(6) analysis of experimental results: and drawing an alkali sensitivity evaluation experimental curve by taking the cumulative injection volume multiple of the alkaline fluid as an abscissa and the core liquid permeability retention rate at corresponding different injection volume multiples as an ordinate.
(6) And (3) data processing:
and (3) performing a certain sensitivity experiment, recording experimental data, drawing an experimental curve (figure 1) taking injection volume multiple as an abscissa and taking permeability retention rate as an ordinate, and fitting a relation between the permeability retention rate and the injection volume multiple as shown in formula (8):
wherein: k (K) n Core permeability under different injection volume multiples for a certain sensitivity experiment; k (K) i Initial permeability for the core; PV is the injection volume multiple;
step two, a three-dimensional geological model is established for the target block according to geological data, and the production process is simulated by using the initial permeability of the stratum to obtain the flowing PV number of the matrix grid; obtaining the permeability of each matrix grid corresponding to different injection volume multiples according to the relation between the permeability retention rate and the injection volume multiples after the sensitive damage by the obtained flow PV number corresponding to each matrix grid, obtaining the permeability of all matrix grids of the target area, and correcting the three-dimensional geological model;
(1) according to geological data such as logging, a three-dimensional geological model is built for a target block, the geological model is a three-dimensional grid body, the built reservoir grid data model represents the flow distribution rule of reservoir fluid, and each grid has a series of properties such as permeability, water saturation, PV number, grid flow speed and the like.
(2) First, the initial permeability is input to the geologic model, representing a time step sequence with the set t= {1,2,3, …, T, …, m } where T represents one time step and m is the last time step. Let each time step represent the injection amount of the injection well into the foreign fluid at that time step, the specific injection amount may be dependent on the actual situation. Simulating the processes of drilling, fracturing or water injection, and the like, and obtaining the PV number of each matrix grid at each time step t in the contact process of reservoir rock and external fluid when external fluid is injected.
(3) Substituting the corresponding PV number of the first grid of the first time step into formula 8 to obtain:
obtaining the permeability K of the first grid corresponding to the time step through calculation (1,1,1,1) ：
K (1,1,1,1) ＝K i ×f(PV) (1,1,1,1) (10)
Of particular note is: when the case is velocity sensitivity, the average flow rate through each grid needs to be considered, and through the first step, the corresponding relation between the reservoir permeability retention rate and the injection volume multiple at the flow rate is found.
Namely, the formulas (9), (10) are changed to:
(4) repeating the above steps to obtain the permeability K of the second grid in the first time step (1,2,1,1) Until the last grid permeability K (1,i,j,k) Ending the calculation to obtain a permeability set K of all grids of the first time step 1 ＝{K (1,1,1,1) ,…,K (1,i,j,k) }。
(5) The second time step repeats steps (3) (4) until the simulation ends for the mth time step. Each time step can obtain the permeability set of all grids of the time step, so that the total set K= { K 1 ,…,K m And represents the set of permeabilities for all time steps.
Handle penetrationRate set K 1 And inputting all grids of the geological model, and correcting grid data to obtain the geological model corrected by the first time step.
Simulating a production process based on a three-dimensional geological model to obtain ideal productivity of a production well; simulating the production process again based on the corrected three-dimensional geological model to obtain the simulated productivity of the production well;
(1) inputting the initial permeability into a geological model, simulating the production process, and obtaining ideal production capacity data P of the production well output by the geological model i (ideal capacity without suffering sensitive damage).
Based on the three-dimensional geological model corrected by the first time step, simulating the production process to obtain the productivity P of the injection quantity corresponding to the first time step 1 。
(3) Repeating the step (2), and simulating the production process until the permeability of the mth time step is integrated into K m Inputting a model and simulating the end of production. Obtaining the capacity set P= { P of all time steps 1 ,P 2 ,…,P t ,…,P m }. Comparing and analyzing the capacity set P and the ideal capacity P under different injection amounts i 。
Step four, obtaining the reservoir productivity damage rate according to the ideal productivity of the production well and the simulated productivity of the production well, and evaluating the reservoir sensitivity of the production well according to the reservoir productivity damage rate;
the rate of reservoir capacity damage at different injection rates of the exogenous fluid (equation 13) was calculated and used as an index for evaluating reservoir sensitivity (table 1).
Wherein: j is the productivity damage rate; p (P) t The productivity under different injection amounts is achieved; p (P) i Ideal productivity at different injection volumes.
TABLE 1 reservoir sensitivity evaluation index
| Yield damage rate% | Sensitivity evaluation |
| J≤5％ | Weak and weak |
| 5％<J≤10％ | Strong strength |
| J>10％ | Adjusting construction scheme |
Examples
In this example, an X oilfield fracturing production well is taken as an example, and a method for evaluating reservoir sensitivity by a productivity damage rate will be described.
The invention relates to a method for evaluating reservoir sensitivity through productivity damage rate, which mainly comprises the following steps:
step 1, taking a core of an X oil field, cutting the core with the diameter of about 2.5cm and the length of 4-7cm according to a SYT5358-2010 core preparation method, drying at 60 ℃ to constant weight, and measuring the length, diameter and porosity of the core; and checking the air tightness of the device, wherein the monitoring time is not less than 48 hours. Table 2 is an example table of X oilfield core experimental data acquisition/processing.
Table 2X example table for core experimental data acquisition/processing in oil field
| Core diameter D/cm | Core length L/cm | Core porosity phi/% |
| 2.45 | 5.35 | 11.33 |
Step 2, preparing simulated formation water under the condition of room temperature, then saturating the core with the simulated formation water, putting the core into a core holder, slowly adjusting confining pressure to 2MPa, displacing the core with the simulated formation water, and measuring the initial permeability K of the core i . And (3) calculating the initial permeability of the core according to a formula (1), and calculating the pore volume of the core according to a formula (2). Calculated pore volume V p Is 2.86cm 3 Initial permeability K i Is 12.64 multiplied by 10 -3 μm 2 。
And 3, then, using the fracturing fluid to displace the core, stopping after 15 times of core pore volume (PV for short) is displaced, enabling the core to react with the fracturing fluid for more than 12 hours, adjusting the flow rate to the initial flow rate, and then measuring the permeability of the core by using simulated formation water.
Step 4, data processing: data are recorded Table 3, and the permeability retention of the water sensitive experiment is calculated according to equation (4).
Table 3X oil field core water sensitivity experimental test data
Step 5, analyzing experimental results: and drawing a water sensitivity evaluation experiment curve (figure 2) by taking the cumulative injection volume multiple of the fracturing fluid as an abscissa and taking the core permeability retention rate corresponding to different injection volume multiples as an ordinate. Fitting a relation between the permeability retention rate and the injection volume multiple of the water sensitivity experiment as shown in a formula (14):
and 6, establishing a three-dimensional geological model for the X oil field according to geological data such as well logging and the like, wherein the constructed reservoir grid data model represents the flow distribution rule of reservoir fluid.
Step 7, firstly, inputting initial permeability into a geological model, wherein the set t= {1,2,3, …, T, …,8} represents a time step sequence, wherein T represents one time step, and 8 represents the last time step. Let each time step represent the injection amount of the injection well into the foreign fluid at that time step. Simulating the water injection process of the fracturing well, and obtaining the PV number of each matrix grid at each time step t in the contact process of reservoir rock and external fluid when the external fluid is injected into the fracturing well.
Step 8, substituting the relation (formula 14) of the reservoir permeability retention rate and the injection volume multiple obtained in the first step into the corresponding PV number of the first grid in the first time step, and obtaining the permeability K of the first grid corresponding to the time step through calculation (1,1,1,1) 。
Step 9, repeating the previous step to obtain a permeability set K of all grids in the first time step 1 ＝{K (1,1,1,1) ,…,K (1,i,j,k) }；
Step 10, collecting the permeability K 1 And inputting all grids of the geological model, and correcting grid data to obtain the geological model corrected by the first time step.
Step 11, repeating the steps 8 and 9 in the second time step until the simulation of the 8 th time step is finished. Each time step can obtain the permeability set of all grids of the time step, so that the total set K= { K 1 ,…,K 8 And represents the set of permeabilities for all time steps.
Step 12, inputting the initial permeability into a geological model, simulating a production process, and obtaining ideal production data P of the fractured well output by the geological model i (ideal capacity without suffering sensitive damage).
Step 13, simulating a production process based on the three-dimensional geological model corrected by the first time step to obtain the productivity P of the injection quantity corresponding to the first time step 1 。
Step 14, repeating the step 13, and simulating the production process until the permeability of the 8 th time step is integrated into K 8 Inputting a model and simulating the end of production. Obtaining the capacity set P= { P of all time steps 1 ,P 2 ,…,P t ,…,P 8 }。
Step 15, finally, according to the definition of the traditional sensitivity evaluation method, the permeability K obtained by the water sensitivity experiment is calculated min 8.11×10 -3 μm 2 Inputting all grids of the geological model, correcting grid data, simulating the production process, and obtaining the productivity P produced by fracturing the well by the traditional sensitivity evaluation method min . All simulated production data for the X-field are shown in Table 4.
Table 4X oilfield simulation capacity
Step 16, consulting the X oilfield on-site production data to obtain the productivity data of the fracturing well, and actually injecting the fracturing fluid 300m on site 3 The actual cumulative capacity was 3.71×10 4 t. According to the productivity set P under different injection amounts and the productivity P obtained by the traditional reservoir sensitivity evaluation method min And comparing with the actual yield on site, and evaluating the accuracy of the yield simulation of the method. A graph is drawn (fig. 3). As can be seen from the graph data, the simulated productivity and the actual productivity of the method are only 2.16% different, while the simulated productivity and the actual productivity of the traditional method are 11.05% different. Therefore, the simulation yield of the method is more accurate, and a solid foundation is provided for accurately evaluating the sensitivity of the reservoir later.
Step 17, capacity data obtained based on the corrected three-dimensional geological model are obtained according to the capacity set P and the ideal capacity P under different injection amounts i The ratio is substituted into formula (13) to calculate the productivity damage rate of the reservoir, data table 5 is obtained, and the reservoir condition is judged by referring to the evaluation index (table 1) of the reservoir sensitivity.
TABLE 5 reservoir Capacity damage Rate
The productivity data are compared and analyzed, and the damage degree of the stratum to the productivity of the reservoir when different injection amounts of fluid are injected into the stratum can be evaluated. In combination with the analysis of the actual injection quantity, the injection quantity was 300m 3 The reservoir productivity damage rate was 4.86% and reservoir sensitivity was rated weak. Conventional reservoir sensitivity evaluation generally adopts core displacement experiments to evaluate permeability change, namely permeability of cores before and after displacement to calculate permeability retention rate, wherein higher values indicate better oil layer protection effect, but the theoretical evaluation is only performed on reservoir sensitivity.
Through Table 5, it can be seen that the conventional evaluation method has larger error in evaluating the sensitivity of the reservoir and cannot truly reflect the damage condition of the reservoir, and the present patent proposes a reservoir sensitivity evaluation method considering the nonuniform damage of the reservoir, which is favorable for accurately evaluating the reservoir and improving the oil and gas productivity and the economic benefit of oil and gas field development.
The present invention is not limited to the above-mentioned embodiments, but is not limited to the above-mentioned embodiments, and any person skilled in the art can make some changes or modifications to the equivalent embodiments without departing from the scope of the technical solution of the present invention, but any simple modification, equivalent changes and modifications to the above-mentioned embodiments according to the technical substance of the present invention are still within the scope of the technical solution of the present invention.
Claims (6)
1. A method for evaluating reservoir sensitivity by productivity impairment, comprising the steps of:
firstly, taking a core on a target block site, carrying out sensitive injury experiments with different injection multiples on the core of the target block, and determining permeability retention rate after sensitive injury;
drawing a curve of permeability retention rate and injection volume multiple after the sensitive injury, and fitting a relation between permeability retention rate and injection volume multiple after the sensitive injury;
step three, a three-dimensional geological model is established for the target block according to geological data, and the production process is simulated by using the initial permeability of the stratum to obtain the flowing PV number of the matrix grid; obtaining the permeability of each matrix grid corresponding to different injection volume multiples according to the relation between the permeability retention rate and the injection volume multiples after the sensitive damage by the obtained flow PV number corresponding to each matrix grid, obtaining the permeability of all matrix grids of the target area, and correcting the three-dimensional geological model;
simulating a production process based on a three-dimensional geological model to obtain ideal productivity of a production well; simulating the production process again based on the corrected three-dimensional geological model to obtain the simulated productivity of the production well;
and fifthly, obtaining the damage rate of the productivity of the reservoir according to the ideal productivity of the production well and the simulated productivity of the production well, and evaluating the sensitivity of the reservoir of the production well according to the damage rate of the productivity of the reservoir.
2. The method of claim 1, wherein the step one sensitivity injury test comprises a rapid sensitivity, a water sensitivity, a salt sensitivity, an acid sensitivity, and an alkali sensitivity injury test.
3. The method of claim 1, wherein the relation between the permeability retention rate and the injection volume multiple after the sensitive injury in the second step is:
wherein: k (K) n Core infiltration under different injection volume multiples for a certain sensitivity experimentTransmittance; k (K) i Initial permeability for the core; PV is the injection volume multiple.
4. The method for evaluating reservoir sensitivity by productivity impairment ratio of claim 1, wherein the specific process of step three is as follows:
step 31, a three-dimensional geological model is established for the target block according to geological data, wherein the three-dimensional geological model is a three-dimensional grid body, the established reservoir grid data model represents the flow distribution rule of reservoir fluid, and each grid has a series of attributes;
step 32, inputting initial permeability into a three-dimensional geological model, wherein the set T= {1,2,3, …, T, …, m } represents a time step sequence, T represents a time step, and m represents a final time step; making each time step represent the injection amount of the external fluid injected by the injection well in the time step, and obtaining the PV number of each matrix grid in each time step t when the external fluid is injected;
step 33, calculating to obtain the permeability of the first grid corresponding to the first time step according to the PV number corresponding to the first grid of the first time step;
step 34, repeating the previous step, and obtaining the permeability of the second grid in the first time step until the calculation of the permeability of the last grid is finished, so as to obtain a permeability set of all grids in the first time step;
step 35, repeating step 33 and step 34 until the m-th time step is simulated, wherein each time step can obtain the permeability set of all grids of the time step;
and 36, inputting the permeability set into all grids of the geological model, and correcting the grid data to obtain a corrected three-dimensional geological model.
5. The method for evaluating reservoir sensitivity by capacity impairment ratio according to claim 1, wherein the calculation formula of the reservoir capacity impairment ratio in step five is:
wherein: j is the productivity damage rate; p (P) t The productivity under different injection amounts is achieved; p (P) i Ideal productivity at different injection volumes.
6. The method for evaluating reservoir sensitivity by productivity impairment ratio of claim 1, wherein in step five, reservoir sensitivity is evaluated as weak when reservoir productivity impairment ratio J is less than or equal to 5%;
when the damage rate of the productivity of the reservoir is 5 percent and J is less than or equal to 10 percent, the sensitivity of the reservoir is evaluated as strong;
reservoir sensitivity was evaluated as adjusting the construction schedule when the reservoir capacity damage rate J > 10%.
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