A method and system for predicting multiphase productivity of horizontal well water injection in tight oil reservoirs

Abstract

The present invention belongs to the technical field of oil and gas field development and discloses a method and system for predicting the multiphase capacity of horizontal well water injection in tight oil reservoirs. The method comprises determining various parameters of the oil reservoir and fluid; calculating the formation pressure and saturation after water injection when the water injection process is instantaneously completed; calculating the saturation dynamics during the soaking and imbibition process; calculating the total production using the saturation field after the soaking as the initial field, and splitting the oil and water production according to the total production and relative permeability curves; calculating the pressure field during the well opening and production process; calculating the crossflow rate from the low permeability zone of the matrix to the high permeability zone of the fracture, updating the saturation field of each zone, and outputting the results. The method is based on a linear flow partitioning model, fully considering the impact of imbibition on water injection development, and using the volume balance principle to characterize the energy replenishment and consumption during the water injection process, thereby realizing the multiphase capacity prediction of water injection after volume fracturing of horizontal wells. The method is suitable for predicting the multiphase capacity of horizontal well water injection in tight oil reservoirs that considers the imbibition process.

Description

Technical Field

[0001] The present invention belongs to the technical field of oil and gas field development, and in particular relates to a method and system for predicting multiphase productivity of horizontal well water injection throughput in tight oil reservoirs. Background Art

[0002] Currently, low-grade reservoirs dominated by low permeability, low abundance, and tight oil have become strategic resources for China's oil development. Ultra-low permeability and tight oil reservoirs have poor reservoir properties, resulting in low yields from conventional fracturing and water injection development, and cumulative oil production struggles to reach the economic limit. Volumetric reconstruction technology has helped improve the productivity of individual wells, but ultra-low permeability reservoirs generally exhibit low production and low fluids, and high injection-to-production ratios with limited well recovery. Initially, individual well productivity increases, but production declines rapidly, and recovery rates are low, necessitating an urgent need to replenish formation energy. Water injection is an effective energy-boosting development method that can increase individual well recovery.

[0003] After replenishing formation energy in ultra-low permeability and tight oil reservoirs, traditional productivity prediction methods are no longer applicable. The production patterns and mechanisms of reservoirs after replenishment differ from conventional understanding. The mechanism of water injection huff-and-puff is primarily the replenishment of formation energy and imbibition. After water injection and wellbore shut-in, capillary forces cause water in the fractures to imbibe along smaller pore throats into the matrix pores. Pressure within the fracture system begins to decrease, and the pressure wave continues to propagate. Because both the injection and production fractures are closed during this phase, a new pressure equilibrium field forms in the formation. Driven by the combined effects of pressure gradient and capillary forces, the injected water enters relatively low-permeability oil layers and oil-bearing pores deep within the matrix, displacing crude oil into the fracture system. This expands the imbibition reach, facilitates the full utilization of imbibition, and improves waterflood development effectiveness. The crude oil displaced into the fracture system, driven by viscous forces, flows along the fracture system toward the production fractures. Pressure in the fracture system continues to decrease, and the crude oil in the matrix, driven by the pressure differential, continuously flows from areas of low water saturation to areas of high water saturation.

[0004] The imbibition mechanism plays an important role in the water injection huff-and-puff development process of tight oil reservoirs after volume fracturing. Therefore, in order to accurately predict the production capacity of horizontal well water injection huff-and-puff in tight oil reservoirs and provide theoretical guidance for the exploitation of tight oil reservoirs, it is urgent to propose a multiphase production capacity prediction method for horizontal well water injection huff-and-puff in tight oil reservoirs.

[0005] Through the above analysis, the problems and defects of the existing technology are as follows:

[0006] (1) The existing ultra-low permeability and tight oil reservoirs have poor physical properties, and conventional fracturing and water injection development has low production, and the cumulative oil production is difficult to reach the economic limit.

[0007] (2) Existing ultra-low permeability reservoirs generally have the characteristics of low production and low liquid content, high injection-production ratio, but difficult oil wells to be effective. In the initial stage, the production of single wells decreases rapidly and the recovery rate is low. There is an urgent need to replenish formation energy.

[0008] (3) After the ultra-low permeability and tight oil reservoirs replenish formation energy, the traditional production capacity prediction method is no longer applicable. The rules and mechanisms of reservoir production after energy replenishment are different from conventional knowledge. Summary of the Invention

[0009] To overcome the problems existing in the related art, the disclosed embodiments of the present invention provide a method and system for predicting the multiphase productivity of horizontal well water injection in tight oil reservoirs. In particular, the present invention relates to a method, system, medium, equipment, and terminal for predicting the multiphase productivity of horizontal well water injection in tight oil reservoirs that considers the imbibition process. The technical solution is as follows:

[0010] The present invention is achieved by providing a method for predicting the multiphase capacity of horizontal well water injection in a tight oil reservoir. The method comprises: determining various parameters of the oil reservoir and the fluid; calculating the formation pressure and saturation after water injection when the water injection process is instantaneously completed; calculating the saturation dynamics during the well soaking and imbibition process; calculating the total production using the saturation field after the well soaking as the initial field, and splitting the oil and water production according to the total production and relative permeability curves; calculating the pressure field during the well opening and production process; calculating the crossflow rate from the low permeability zone of the matrix to the high permeability zone of the fracture, updating the saturation field of each zone and outputting the result.

[0011] Furthermore, the method for predicting multiphase productivity of horizontal well water injection in tight oil reservoirs includes the following steps:

[0012] Step 1: Determine various parameters of reservoir, fluid and production;

[0013] Step 2: When the water injection process is completed instantly, the average formation pressure p before the well is shut down is calculated based on the volume balance principle. ai , initial water saturation S in the hyperpermeable zone whi , initial oil saturation S in high permeability zone ohi , initial water saturation S in low permeability zone wli and the initial oil saturation S in the low permeability zone oli ;

[0014] Step 3: Let the initial number of days of soaking the well be t s =0, initial water saturation S of the high permeability zone during the soaking process whs (0) = S whi , initial oil saturation S in high permeability zone ohs (0) = S ohi , initial water saturation S in the low permeability zone wls (0) = S wli , initial oil saturation S in low permeability zone ols (0) = S oli ;

[0015] Step 4: Let Δts =1,t s =t s +1, calculate the tth time in the soaking process s Daily absorption capacity Q im (t s );

[0016] Step 5: Update the tth s The water saturation S of the high permeability zone whs (t s ), oil saturation S in high permeability zone ohs (t s ), water saturation S in low permeability zone wls (t s ) and oil saturation S in low permeability zone ols (t s ), if t s Greater than the total soaking time t m , then go to step 6, otherwise return to step 4;

[0017] Step 6: Let the initial number of days of production be t p =0, initial water saturation S in high permeability zone during well production whp (0) = S whs (t m ), initial oil saturation S in high permeability zone ohp (0) = S ohs (t m ), initial water saturation S in the low permeability zone during well production wlp (0) = S wls (t m ), initial oil saturation S in low permeability zone olp (0) = S ols (t m ), the initial average formation pressure p during well production av (0) = p ai , the initial oil phase crossflow rate Q during well production co (0) = 0, initial water phase crossflow rate Q cw (0) = 0, calculate the initial average water saturation S of all areas during the well production process w (0) and the initial average oil saturation S o (0);

[0018] Step 7: Let Δt p =1,t p =t p +1, solve the tth p Total daily output q t (t p );

[0019] Step 8: Based on the water phase relative permeability curve and the oil phase relative permeability curve, use linear interpolation to obtain the t-th p Average water saturation S before production starts w (t p -1) The corresponding water phase relative permeability k rw (t p ) and oil phase relative permeability k ro (t p );

[0020] Step 9: Split the oil and water production according to relative permeability to obtain the t p Tianshui output q w (t p ) and oil production q o (t p );

[0021] Step 10: Calculate the pressure drop dp(t p ), and thus calculate the average pressure p av (t p ); Calculate till t p Total oil phase cross-flow rate Q per day co (t p ) and the total water phase cross-flow rate Q cw (t p );

[0022] Step 11: water saturation S in the hypertonic zone whp (t p ), oil saturation S in high permeability zone ohp (t p ), water saturation S in low permeability zone wlp (t p ) and oil saturation S in low permeability zone olp (t p ) to update;

[0023] Step 12: average oil saturation S o (t p ) and average water saturation S w (t p ) is updated. If t is greater than the production time T, the result is output, otherwise return to step 7.

[0024] In one embodiment, the reservoir, fluid and production parameters in step 1 include: reservoir thickness h, reservoir width x e , horizontal well length L w , original formation pressure p i , bottom hole pressure p wf , original oil saturation S oi, initial water saturation S wi , inner zone reservoir permeability k I , inner zone fracture reservoir permeability k IF , outer zone reservoir permeability k O , crossflow coefficient λ, elastic storage volume ratio ω, external reservoir porosity φ O , inner zone matrix porosity φ I , the overall porosity of the inner matrix φ Ib , the porosity of the micro-fracture medium in the inner zone φ IF , the porosity of the micro-fracture medium under the entire inner reservoir φ IFb , comprehensive compression coefficient of inner area c I , comprehensive compression coefficient of outer area c O , number of cracks n F , main fracture permeability k F , main fracture porosity φ F , crack width w F 、Crack half length x F , wellbore radius r w , comprehensive crack compression coefficient c F , water injection volume V inj , soaking time t m , imbibition diffusion coefficient D, total soaking time t m , production time T, crude oil viscosity μ o , water viscosity μ w , crude oil density ρ o , water density ρ w , crude oil volume coefficient B o , water volume coefficient B w , water compressibility c w , oil compression coefficient c o , bound water saturation S oc , residual oil saturation S wc , water phase relative permeability curve and oil phase relative permeability curve.

[0025] In one embodiment, the average formation pressure P before the well is soaked in step 2 is ai , initial water saturation S in the hyperpermeable zone whi , initial oil saturation S in high permeability zone ohi , initial water saturation S in low permeability zone wli and the initial oil saturation S in the low permeability zone oli The calculation formula is as follows:

[0026]

[0027]

[0028] S ohi =1-Swhi ;

[0029]

[0030] S oli =1-S wli ;

[0031] Among them, V t =x F hH w is the volume of the inner region, is the average porosity of the reservoir before water injection, V F =n F w F x F h is the volume of the artificial crack, is the proportion of high permeability area in the reservoir volume after fracturing.

[0032] In one embodiment, the imbibition amount Q in step 4 is im (t s ) is calculated as follows:

[0033]

[0034] Among them, R0 is the maximum recovery degree and λ is the imbibition intensity.

[0035] In one embodiment, the tth s The water saturation S of the high permeability zone whs (t s ), oil saturation S in high permeability zone ohs (t s ), water saturation S in low permeability zone wls (t s ) and oil saturation S in low permeability zone ols (t s ) is calculated as follows:

[0036]

[0037] S ohs (t s )=1-S whs (t s );

[0038]

[0039] S ols (t s )=1-S wls (t s );

[0040] in, As of ts Total percolation volume per day.

[0041] In one embodiment, the initial average water saturation S of all zones during the well production process in step 6 is w (0) and the initial average oil saturation S o The calculation formula of (0) is as follows:

[0042]

[0043] S w (0)=1-S o (0);

[0044] Among them, N io =V t S oi φ i / B o , N iw =V t S wi φ i / B w , N iot =N io +(x e -x F )y e h oi φ O / B o , N iwt =N iw +(x e -x F )y e h wi φ O / B w .

[0045] In one embodiment, the total yield q in step seven is t (t p ) is calculated as follows:

[0046]

[0047] Among them, p wD is the dimensionless pressure, μ m =S w (t p -1)μ w +S o (t p -1)μ o is the average viscosity.

[0048] In one embodiment, the tth step in step nine p Tianshui output q w(t p ) and oil production q o (t p ) is calculated as follows:

[0049] q w (t p )=C wp q t (t p );

[0050] q o (t p )=C op q t (t p );

[0051] in, is the water production coefficient, is the oil production coefficient.

[0052] In one embodiment, the pressure drop dp (t p ) and the average pressure p av (t p ) is calculated as follows:

[0053]

[0054]

[0055] in,

[0056] As of t p Total oil phase cross-flow rate Q per day co (t p ) and the total water phase cross-flow rate Q cw (t p ) is calculated as follows:

[0057]

[0058] In one embodiment, the water saturation S of the hypertonic zone in step 11 is whp (t p ), oil saturation S in high permeability zone ohp (t p ), water saturation S in low permeability zone wlp (t p ) and oil saturation S in low permeability zone olp (t p ) is calculated as follows:

[0059] a1=4V tt φ i R hp Swhp (0)-N pw (t p )B w -Q cw (t p )

[0060] a2=4V tt φ i R hp S ohp (0)-N po (t p )B o +Q co (t p )

[0061]

[0062] S ohp (t p )=1-S whp (t p )

[0063] b1=4V tt φ i (1-R hp )S whp (0)-Q cw (t p )

[0064] b2=4V tt φ i (1-R hp )S ohp (0)-Q co (t p )

[0065]

[0066] S olp (t p )=1-S wlp (t p )

[0067] in, As of t p The total water production per day, As of t p Total oil production per day.

[0068] In one embodiment, the average oil saturation S in step 12 is o (t p ) and average water saturation S w (t p ) is calculated as follows:

[0069]

[0070] S w (t p )=1-S o (t p ).

[0071] Another object of the present invention is to provide a system for predicting the multiphase productivity of water injection throughput in a tight oil reservoir horizontal well using the multiphase productivity prediction method for water injection throughput in a tight oil reservoir horizontal well. The system comprises:

[0072] The saturation calculation module is used to determine various parameters of the reservoir and fluid. When the water injection process is completed instantly, the formation pressure and saturation after water injection are calculated, and the saturation dynamics during the soaking and imbibition process are calculated.

[0073] The oil-water production splitting module is used to calculate the total production using the saturation field after the well is soaked as the initial field, and split the oil-water production according to the total production and relative permeability curves;

[0074] The saturation field update module is used to calculate the pressure field during the well production process, calculate the crossflow rate from the low permeability area of ​​the matrix to the high permeability area of ​​the fracture, update the saturation field of each area and output the results.

[0075] Another object of the present invention is to provide a computer device, which includes a memory and a processor, wherein the memory stores a computer program, and when the computer program is executed by the processor, the processor executes the steps of the method for predicting the multiphase production capacity of horizontal well water injection in tight oil reservoirs.

[0076] Another object of the present invention is to provide a computer-readable storage medium storing a computer program, which, when executed by a processor, enables the processor to execute the steps of the method for predicting multiphase productivity of horizontal well water injection in tight oil reservoirs.

[0077] Another object of the present invention is to provide an information data processing terminal, which is installed on an electronic device and provides a user input interface to implement the multiphase productivity prediction system for horizontal well water injection in tight oil reservoirs.

[0078] Combining all the above technical solutions, the advantages and positive effects of the present invention are as follows:

[0079] First, in view of the technical problems existing in the above-mentioned prior art and the difficulty of solving these problems, this paper closely combines the technical solutions to be protected by the present invention and the results and data during the research and development process, and analyzes in detail and in depth how the technical solutions of the present invention solve the technical problems and some creative technical effects brought about by solving the problems. The specific description is as follows:

[0080] In order to improve the accuracy of calculating the water injection throughput capacity of horizontal wells in tight oil reservoirs and provide theoretical guidance for the exploitation of tight oil reservoirs, the present invention provides a method for predicting the multiphase capacity of water injection throughput of horizontal wells in tight oil reservoirs considering the imbibition process. This method fully considers the impact of imbibition on water injection throughput development and is suitable for predicting the multiphase capacity of water injection throughput of horizontal wells in tight oil reservoirs considering the imbibition process.

[0081] The multiphase capacity prediction method for water injection huff-and-puff of horizontal wells in tight oil reservoirs of the present invention takes into account the imbibition effect during the water injection huff-and-puff process after volume fracturing of tight oil horizontal wells, reducing the error of horizontal well capacity prediction by 31.15%; oil and water production rates are calculated separately, and multiphase capacity prediction is additionally achieved compared to traditional liquid production prediction.

[0082] Second, considering the technical solution as a whole or from the perspective of the product, the technical effects and advantages of the technical solution to be protected by the present invention are described in detail as follows:

[0083] The method for predicting the multiphase productivity of horizontal well water injection in tight oil reservoirs provided by the present invention is based on a linear flow partitioning model, takes into account the dynamic changes of imbibition, and uses the volume balance principle to characterize the replenishment and consumption of energy during the water injection process, thereby realizing the multiphase productivity prediction of water injection after volume fracturing of horizontal wells.

[0084] Third, as auxiliary evidence for the inventiveness of the claims of the present invention, it is also reflected in the following important aspects:

[0085] (1) The expected benefits and commercial value of the technical solution of the present invention after transformation are as follows: The multiphase capacity prediction method for water injection throughput of horizontal wells in tight oil reservoirs provided by the present invention can provide technical services for multiphase capacity prediction of water injection throughput after volume fracturing of horizontal wells, helping oil fields to carry out reasonable production planning.

[0086] (2) The technical solution of the present invention fills the technical gap in the prediction of multiphase production capacity of water injection after horizontal well volume fracturing in the domestic and foreign industries. Based on the linear flow partition model, the dynamic changes of imbibition are taken into account, and the phase permeability is used to split the oil and water production, which greatly improves the accuracy of the prediction.

[0087] (3) The technical solution of the present invention solves the technical problem in the industry regarding the prediction of multi-phase production capacity of water injection after horizontal well volume fracturing.

[0088] (4) The technical solution of the present invention overcomes technical prejudice and takes into account the neglected dynamic change of imbibition during water injection and huff-and-puff. By solving the imbibition equation, the imbibition volume is obtained, thereby updating the saturation field and clarifying the production principle of water injection and huff-and-puff. BRIEF DESCRIPTION OF THE DRAWINGS

[0089] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present disclosure and, together with the description, serve to explain the principles of the present disclosure;

[0090] Figure 1 This is a flow chart of a method for predicting multiphase production capacity of horizontal well water injection in tight oil reservoirs provided by an embodiment of the present invention;

[0091] Figure 2 1 is a schematic diagram of a method for predicting multiphase productivity of horizontal well water injection in tight oil reservoirs provided by an embodiment of the present invention;

[0092] Figure 3 is a phase permeability curve diagram provided by an embodiment of the present invention;

[0093] Figure 4 This is a diagram of saturation changes in a high permeability zone during a soaking process provided by an embodiment of the present invention;

[0094] Figure 5 This is a comparison chart of the calculated and actual daily oil production values ​​provided by an embodiment of the present invention;

[0095] Figure 6 This is a comparison chart of the calculated total oil production value and the actual value provided by the embodiment of the present invention;

[0096] Figure 7 This is a diagram of saturation changes in a high permeability zone during well production provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0097] To make the above-mentioned objects, features, and advantages of the present invention more readily apparent, specific embodiments of the present invention are described in detail below with reference to the accompanying drawings. The following description sets forth numerous specific details to facilitate a full understanding of the present invention. However, the present invention can be implemented in many other ways than those described herein, and those skilled in the art may make similar modifications without departing from the scope of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0098] 1. Explanation of the embodiment:

[0099] like Figure 1 As shown, the method for predicting multiphase productivity of horizontal well water injection in tight oil reservoirs provided by the embodiment of the present invention includes the following steps:

[0100] S101, determine various parameters of the reservoir and fluid; when the water injection process is completed instantly, calculate the formation pressure and saturation after water injection, and calculate the saturation dynamics during the soaking and imbibition process;

[0101] S102, using the saturation field after soaking as the initial field, calculate the total production, and split the oil and water production according to the total production and relative permeability curve;

[0102] S103, calculate the pressure field during the well production process, calculate the crossflow rate from the low permeability area of ​​the matrix to the high permeability area of ​​the fracture, update the saturation field of each area and output the result.

[0103] As a preferred embodiment, Figure 2 As shown, the method for predicting the multiphase productivity of horizontal well water injection in tight oil reservoirs considering the imbibition process provided by the embodiment of the present invention specifically includes the following steps:

[0104] (1) Determine various parameters of reservoir, fluid and production;

[0105] (2) Assuming that the water injection process is completed instantly, the average formation pressure p before well soaking is calculated based on the volume balance principle. ai and the initial water saturation S in the hyperpermeable zone whi , initial oil saturation S in high permeability zone ohi , initial water saturation S in low permeability zone wli , initial oil saturation S in low permeability zone oli ;

[0106] (3) Let the initial number of days of soaking the well be t s =0, initial water saturation S of the high permeability zone during the soaking process whs (0) = S whi , initial oil saturation S in high permeability zone ohs (0) = S ohi , initial water saturation S in the low permeability zone wls (0) = S wli , initial oil saturation S in low permeability zone ols (0) = S oli ;

[0107] (4) Let Δt s =1,t s =t s +1, calculate the tth time in the soaking process s Daily absorption capacity Q im (t s );

[0108] (5) Update the tth s The water saturation S of the hypertonic zone whs (t s ), oil saturation S in high permeability zoneohs (t s ), water saturation S in low permeability zone wls (t s ), oil saturation S in low permeability zone ols (t s ), if t s Greater than the total soaking time t m , go to step (6), otherwise go to step (4);

[0109] (6) Let the initial number of days of production at the well be t p =0, initial water saturation S in high permeability zone during well production whp (0) = S whs (t m ), initial oil saturation S in high permeability zone ohp (0) = S ohs (t m ), initial water saturation S in the low permeability zone during well production wlp (0) = S wls (t m ), initial oil saturation S in low permeability zone olp (0) = S ols (t m ), the initial average formation pressure p during well production av (0) = p ai , the initial oil phase crossflow rate Q during well production co (0) = 0, initial water phase crossflow rate Q cw (0) = 0, calculate the initial average water saturation S of all areas during the well production process w (0), initial average oil saturation S o (0);

[0110] (7) Let Δt p =1,t p =t p +1, solve the tth p Total daily output q t (t p );

[0111] (8) Based on the water phase relative permeability curve and the oil phase relative permeability curve, linear interpolation is used to obtain the t p Average water saturation S before production starts w (t p -1) The corresponding water phase relative permeability k rw (t p ) and oil phase relative permeability k ro (t p );

[0112] (9) Split the oil and water production according to relative permeability to obtain the t p Tianshui output q w (t p ), oil production q o (t p );

[0113] (10) Calculate the pressure drop dp(t p ), and thus calculate the average pressure p av (t p );

[0114] (11) Calculate the end point t p Total oil phase cross-flow rate Q per day co (t p ) and the total water phase cross-flow rate Q cw (t p );

[0115] (12) Water saturation S in the hyperpermeable zone whp (t p ), oil saturation S in high permeability zone ohp (t p ), water saturation S in low permeability zone wlp (t p ), oil saturation S in low permeability zone olp (t p ) to update;

[0116] (13) Average oil saturation S o (t p ), average water saturation S w (t p ) is updated, if t is greater than the production time T, go to step (14), otherwise go to step (7);

[0117] (14) Output the results.

[0118] The parameters of the reservoir, fluid and production in step (1) provided by the embodiment of the present invention are: reservoir thickness h, reservoir width x e , horizontal well length L w , original formation pressure p i , bottom hole pressure p wf , original oil saturation S oi , initial water saturation S wi , inner zone reservoir permeability k I , inner zone fracture reservoir permeability k IF , outer zone reservoir permeability k O , crossflow coefficient λ, elastic storage volume ratio ω, external reservoir porosity φ O , inner zone matrix porosity φI , the overall porosity of the inner matrix φ Ib , the porosity of the micro-fracture medium in the inner zone φ IF , the porosity of the micro-fracture medium under the entire inner reservoir φ IFb , comprehensive compression coefficient of inner area c I , comprehensive compression coefficient of outer area c O , number of cracks n F , main fracture permeability k F , main fracture porosity φ F , crack width w F , crack half length x F , wellbore radius r w , comprehensive crack compression coefficient c F , water injection volume V inj , soaking time t m , imbibition diffusion coefficient D, total soaking time t m , production time T, crude oil viscosity μ o , water viscosity μ w , crude oil density ρ o , water density ρ w , crude oil volume coefficient B o , the volume coefficient of water B w , the compressibility coefficient of water c w , oil compressibility c o , bound water saturation S oc , residual oil saturation S wc , water phase relative permeability curve, oil phase relative permeability curve.

[0119] The embodiment of the present invention provides the average formation pressure P before soaking in step (2) ai and the initial water saturation S in the hyperpermeable zone whi , initial oil saturation S in high permeability zone ohi , initial water saturation S in low permeability zone wli , initial oil saturation S in low permeability zone oli The calculation formula is as follows:

[0120]

[0121]

[0122] S ohi =1-S whi ;

[0123]

[0124] S oli =1-S wli ;

[0125] Among them, V t =x F hH w is the volume of the inner region, is the average porosity of the reservoir before water injection, V F =n F w F x F h is the volume of the artificial crack, is the proportion of high permeability area in the reservoir volume after fracturing.

[0126] In one embodiment, the imbibition amount Q in step 4 is im (t s ) is calculated as follows:

[0127]

[0128] Among them, R0 is the maximum recovery degree and λ is the imbibition intensity.

[0129] The embodiment of the present invention provides the t-th step in step (5) s The water saturation S of the high permeability zone whs (t s ), oil saturation S in high permeability zone ohs (t s ), water saturation S in low permeability zone wls (t s ), oil saturation S in low permeability zone ols (t s ) is calculated as follows:

[0130]

[0131] S ohs (t s )=1-S whs (t s );

[0132]

[0133] S ols (t s )=1-S wls (t s );

[0134] in, As of t s Total percolation volume per day.

[0135] The embodiment of the present invention provides the initial average water saturation S of all regions during the well production process in step (6). w (0), initial average oil saturation S o(0) The calculation formula is as follows:

[0136]

[0137] S w (0)=1-S o (0);

[0138] Among them, N io =V t S oi φ i / B o , N iw =V t S wi φ i / B w , N iot =N io +(x e -x F )y e h oi φ O / B o , N iwt =N iw +(x e -x F )y e h wi φ O / B w ;

[0139] The embodiment of the present invention provides the total yield q in step (7) t (t p ) is calculated as follows:

[0140]

[0141] Among them, p wD is the dimensionless pressure, μ m =S w (t p -1)μ w +S o (t p -1)μ o is the average viscosity.

[0142] The embodiment of the present invention provides the t-th step in step (9) p Tianshui output q w (t p ), oil production q o (t p ) is calculated as follows:

[0143] q w (t p )=Cwp q t (t p );

[0144] q o (t p )=C op q t (t p );

[0145] in, is the water production coefficient, is the oil production coefficient.

[0146] The embodiment of the present invention provides the pressure drop dp (t p ) and the average pressure p av (t p ) is calculated as follows:

[0147]

[0148]

[0149] in,

[0150] The embodiment of the present invention provides the end time t in step (11) p Total oil phase cross-flow rate Q per day co (t p ) and the total water phase cross-flow rate Q cw (t p ) is calculated as follows:

[0151]

[0152] The embodiment of the present invention provides the water saturation S of the hypertonic zone in step (12). whp (t p ), oil saturation S in high permeability zone ohp (t p ), water saturation S in low permeability zone wlp (t p ), oil saturation S in low permeability zone olp (t p ) is calculated as follows:

[0153] a1=4V tt φ i R hp S whp (0)-N pw (t p )B w -Q cw (t p )

[0154] a2=4V tt φ i R hp S ohp (0)-N po (t p )B o +Q co (t p )

[0155]

[0156] S ohp (t p )=1-S whp (t p )

[0157] b1=4V tt φ i (1-R hp )S whp (0)-Q cw (t p )

[0158] b2=4V tt φ i (1-R hp )S ohp (0)-Q co (t p )

[0159]

[0160] S olp (t p )=1-S wlp (t p )

[0161] in, As of t p The total water production per day, As of t p Total oil production per day.

[0162] The embodiment of the present invention provides the average oil saturation S in step (13) o (t p ), average water saturation S w (t p ) is calculated as follows:

[0163]

[0164] S w (t p )=1-S o (tp ).

[0165] The multiphase productivity prediction system for water injection throughput of horizontal wells in tight oil reservoirs provided by the embodiment of the present invention includes:

[0166] The saturation calculation module is used to determine various parameters of the reservoir and fluid. When the water injection process is completed instantly, the formation pressure and saturation after water injection are calculated, and the saturation dynamics during the soaking and imbibition process are calculated.

[0167] The oil-water production splitting module is used to calculate the total production using the saturation field after the well is soaked as the initial field, and split the oil-water production according to the total production and relative permeability curves;

[0168] The saturation field update module is used to calculate the pressure field during the well production process, calculate the crossflow rate from the low permeability area of ​​the matrix to the high permeability area of ​​the fracture, update the saturation field of each area and output the results.

[0169] In the above embodiments, the description of each embodiment has its own focus. For parts that are not described or recorded in detail in a certain embodiment, reference can be made to the relevant description of other embodiments.

[0170] The information interaction, execution process, etc. between the above-mentioned devices / units are based on the same concept as the embodiment of the method of the present invention. Their specific functions and technical effects can be found in the method embodiment part and will not be repeated here.

[0171] Those skilled in the art can clearly understand that, for the convenience and brevity of description, only the division of the above-mentioned functional units and modules is used as an example for illustration. In actual applications, the above-mentioned functions can be distributed and completed by different functional units and modules as needed, that is, the internal structure of the device can be divided into different functional units or modules to complete all or part of the functions described above. The functional units and modules in the embodiment can be integrated into one processing unit, or each unit can exist physically alone, or two or more units can be integrated into one unit. The above-mentioned integrated unit can be implemented in the form of hardware or in the form of software functional units. In addition, the specific names of the functional units and modules are only for the convenience of distinguishing each other, and are not used to limit the scope of protection of the present invention. The specific working process of the units and modules in the above-mentioned system can refer to the corresponding process in the aforementioned method embodiment.

[0172] 2. Application Examples

[0173] As a preferred embodiment, Figure 2 As shown, an embodiment of the present invention provides a method for predicting the multiphase productivity of horizontal well water injection in tight oil reservoirs considering the imbibition process, which specifically includes the following steps:

[0174] (1) Determine the parameters of the reservoir, fluid, and production: reservoir thickness h, reservoir width x e , horizontal well length L w , original formation pressure p i , bottom hole pressure p wf , original oil saturation S oi , initial water saturation S wi , inner zone reservoir permeability k I , inner zone fracture reservoir permeability k IF , outer zone reservoir permeability k O , crossflow coefficient λ, elastic storage volume ratio ω, external reservoir porosity φ O , inner zone matrix porosity φ I , the overall porosity of the inner matrix φ Ib , the porosity of the micro-fracture medium in the inner zone φ IF , the porosity of the micro-fracture medium under the entire inner reservoir φ IFb , comprehensive compression coefficient of inner area c I , comprehensive compression coefficient of outer area c O , number of cracks n F , main fracture permeability k F , main fracture porosity φ F , crack width w F , crack half length x F , wellbore radius r w , comprehensive crack compression coefficient c F , water injection volume V inj , soaking time t m , imbibition diffusion coefficient D, total soaking time t m , production time T, crude oil viscosity μ o , water viscosity μ w , crude oil density ρ o , water density ρ w , crude oil volume coefficient B o , the volume coefficient of water B w , the compressibility coefficient of water c w , oil compressibility c o , bound water saturation S oc , residual oil saturation S wc , water phase relative permeability curve, oil phase relative permeability curve.

[0175] Reservoir thickness h = 12.5m, reservoir width x e =306m, horizontal well length L w =700m, original formation pressure p i =24.525Mpa, bottom hole pressure p wf =20MPa, initial oil saturation S oi=0.691, initial water saturation S wi =0.309, inner reservoir permeability k I =1.974×10 -15 m 2 , inner zone fracture reservoir permeability k IF =0.6×10 -13 m 2 , outer zone reservoir permeability k O =1.974×10 -16 m 2 , crossflow coefficient λ = 300, elastic storage capacity ratio ω = 6.61 × 10 -3 、Porosity of outer reservoir φ O =0.155, inner matrix porosity φ I =0.175, the overall porosity of the inner matrix φ Ib =0.175, porosity of the micro-fracture medium in the inner zone φ IF =4.5×10 -3 , the porosity of the micro-fracture medium under the entire inner reservoir φ IFb =4.5×10 -3 , comprehensive compression coefficient of inner area c I =6.0×10 -9 Pa -1 , comprehensive compression coefficient of outer area c O =2.0×10 -9 Pa -1 , number of cracks n F =23, main fracture permeability k F =3.948×10 -11 m 2 , main fracture porosity φ F =0.45, crack width w F =5mm, crack half length x F =230m, shaft radius r w =0.06m, comprehensive crack compression coefficient c F =6×10 -9 Pa -1 , water injection volume V inj =4508.9m 3 , soaking time t m =30d, imbibition diffusion coefficient D = 1.0×10 -9 m 2 / s, total soaking time t m =30d, production time T=555d, crude oil viscosity μ o =224.2mPa·s, water viscosity μ w =1mPa·s, crude oil density ρ o=0.9g / cm 3 , water density ρ w =1g / cm 3 , crude oil volume coefficient B o =1.2, volume coefficient of water B w =1.0, water compressibility c w =0.000235×10 -6 Pa -1 , oil compressibility c o =0.000635×10 -6 Pa -1 , bound water saturation S oc =0.19, residual oil saturation S wc =0.177, water phase permeability curve and oil phase permeability curve are as follows Figure 3 shown.

[0176] (2) Assuming that the water injection process is completed instantly, the average formation pressure p before well soaking is calculated based on the volume balance principle. ai and the initial water saturation S in the hyperpermeable zone whi , initial oil saturation S in high permeability zone ohi , initial water saturation S in low permeability zone wli , initial oil saturation S in low permeability zone oli ;

[0177] Average formation pressure P before soaking ai and the initial water saturation S in the hyperpermeable zone whi , initial oil saturation S in high permeability zone ohi , initial water saturation S in low permeability zone wli , initial oil saturation S in low permeability zone oli The calculation formula is as follows:

[0178]

[0179]

[0180] S ohi =1-S whi ;

[0181]

[0182] S oli =1-S wli ;

[0183] Among them, V t =x F hH w is the volume of the inner region, is the average porosity of the reservoir before water injection, V F =nF w F x F h is the volume of the artificial crack, is the proportion of high permeability area in the reservoir volume after fracturing.

[0184] In a preferred embodiment of the present invention, the average formation pressure p before soaking is ai =24.98Mpa, initial water saturation S in the hyperpermeable zone whi =0.4714, initial oil saturation S in high permeability zone ohi =0.5286, initial water saturation S in low permeability zone wli =0.3091, initial oil saturation S in low permeability zone oli =0.6909.

[0185] (3) Let the initial number of days of soaking the well be t s =0, initial water saturation S of the high permeability zone during the soaking process whs (0) = S whi , initial oil saturation S in high permeability zone ohs (0) = S ohi , initial water saturation S in the low permeability zone wls (0) = S wli , initial oil saturation S in low permeability zone ols (0) = S oli .

[0186] In a preferred embodiment of the present invention, the initial water saturation S of the high permeability zone during the soaking process is whs (0) = 0.4714, initial oil saturation S in high permeability zone ohs (0) = 0.5286, initial water saturation S in the low permeability zone wls (0) = 0.3091, initial oil saturation S in low permeability zone ols (0)=0.6909.

[0187] (4) Let Δt s =1,t s =t s +1, calculate the tth time in the soaking process s Daily absorption capacity Q im (t s );

[0188] Imbibition Q im (t s ) is calculated as follows:

[0189]

[0190] Among them, R0 is the maximum recovery degree and λ is the imbibition intensity.

[0191] In a preferred embodiment of the present invention, when t s =10,Q im (10) = 3.0379m 3 .

[0192] (5) Update the tth s The water saturation S of the hypertonic zone whs (t s ), oil saturation S in high permeability zone ohs (t s ), water saturation S in low permeability zone wls (t s ), oil saturation S in low permeability zone ols (t s ), if t s Greater than the total soaking time t m , go to step (6), otherwise go to step (4);

[0193] No. t s The water saturation S of the hypertonic zone whs (t s ), oil saturation S in high permeability zone ohs (t s ), water saturation S in low permeability zone wls (t s ), oil saturation S in low permeability zone ols (t s ) is calculated as follows:

[0194]

[0195] S ohs (t s )=1-S whs (t s );

[0196]

[0197] S ols (t s )=1-S wls (t s );

[0198] in, As of t s Total percolation volume per day.

[0199] In a preferred embodiment of the present invention, Q imt (1) = 3.0746m 3 , when t s =10,Q imt (10) = 30.5621m 3 , Swhs (10) = 0.4757, S ohs (10) = 0.5243, S wls (10) = 0.3091, S ols (10) = 0.6909, the saturation change of the high permeability zone during the soaking process is as follows Figure 4 shown.

[0200] (6) Let the initial number of days of production at the well be t p =0, initial water saturation S in high permeability zone during well production whp (0) = S whs (t m ), initial oil saturation S in high permeability zone ohp (0) = S ohs (t m ), initial water saturation S in the low permeability zone during well production wlp (0) = S wls (t m ), initial oil saturation S in low permeability zone olp (0) = S ols (t m ), the initial average formation pressure p during well production av (0) = p ai , the initial oil phase crossflow rate Q during well production co (0) = 0, initial water phase crossflow rate Q cw (0) = 0, calculate the initial average water saturation S of all areas during the well production process w (0), initial average oil saturation S o (0);

[0201] The initial average water saturation S of all areas during well production w (0), initial average oil saturation S o (0) The calculation formula is as follows:

[0202]

[0203] S w (0)=1-S o (0);

[0204] Among them, N io =V t S oi φ i / B o , N iw =V t S wi φ i / B w , N iot=N io +(x e -x F )y e h oi φ O / B o , N iwt =N iw +(x e -x F )y e h wi φ O / B w ;

[0205] In a preferred embodiment of the present invention, S whp (0) = 0.4712, S ohp (0) = 0.5288, S wlp (0) = 0.3091, S olp (0) = 0.6909, p av (0) = 24.98 MPa, S w (0) = 0.3133, S o (0)=0.6867.

[0206] (7) Let Δt p =1,t p =t p +1, solve the tth p Total daily output q t (t p );

[0207] Total output q t The calculation formula is as follows:

[0208]

[0209] Among them, p wD is the dimensionless pressure, μ m =S w (t p -1)μ w +S o (t p -1)μ o is the average viscosity.

[0210] In a preferred embodiment of the present invention, when t p =100,q t (100) = 10.5205m 3 .

[0211] (8) Based on the water phase relative permeability curve and the oil phase relative permeability curve, linear interpolation is used to obtain the tp Average water saturation S before production starts w (t p -1) The corresponding water phase relative permeability k rw (t p ) and oil phase relative permeability k ro (t p ).

[0212] In a preferred embodiment of the present invention, when t p =100, S w (99) = 0.3128, k rw (100) = 0.0670, k ro (100)=0.2326.

[0213] (9) Split the oil and water production according to relative permeability to obtain the t p Tianshui output q w (t p ), oil production q o (t p );

[0214] No. t p Tianshui output q w (t p ), oil production q o (t p ) is calculated as follows:

[0215] q w (t p )=C wp q t (t p );

[0216] q o (t p )=C op q t (t p );

[0217] in, is the water production coefficient, is the oil production coefficient.

[0218] In a preferred embodiment of the present invention, when t p =100,q w (100) = 2.2629m 3 ,q o (100) = 8.2575m 3 .

[0219] (10) Calculate the pressure drop dp(t p ), and thus calculate the average pressure pav (t p );

[0220] Pressure drop after well opening dp(t p ) and the average pressure p av (t p ) is calculated as follows:

[0221]

[0222]

[0223] in,

[0224] In a preferred embodiment of the present invention, when t p =1, V tt =1.7452×10 5 m 3 , dp(1)=9.8752Pa,p av (1) = 2.4985 × 10 7 Pa; when t p =100, V tt =1.5064×10 5 m 3 , dp(100)=634.3205Pa,p av (100) = 2.4899 × 10 7 Pa.

[0225] (11) Calculate the end point t p Total oil phase cross-flow rate Q per day co (t p ) and the total water phase cross-flow rate Q cw (t p );

[0226] As of t p Total oil phase cross-flow rate Q per day co (t p ) and the total water phase cross-flow rate Q cw (t p ) is calculated as follows:

[0227]

[0228] In a preferred embodiment of the present invention, when t p =100, Q co (100) = 0.3433 m 3 , Q cw (100) = 0.0989m 3 .

[0229] (12) Water saturation S in the hyperpermeable zone whp (t p ), oil saturation S in high permeability zone ohp (t p ), water saturation S in low permeability zone wlp (t p ), oil saturation S in low permeability zone olp (t p ) to update;

[0230] Water saturation S in the hyperpermeable zone whp (t p ), oil saturation S in high permeability zone ohp (t p ), water saturation S in low permeability zone wlp (t p ), oil saturation S in low permeability zone olp (t p ) is calculated as follows:

[0231] a1=4V tt φ i R hp S whp (0)-N pw (t p )B w -Q cw (t p )

[0232] a2=4V tt φ i R hp S ohp (0)-N po (t p )B o +Q co (t p )

[0233]

[0234] S ohp (t p )=1-S whp (t p )

[0235] b1=4V tt φ i (1-R hp )S whp (0)-Q cw (t p )

[0236] b2=4V tt φ i (1-Rhp )S ohp (0)-Q co (t p )

[0237]

[0238] S olp (t p )=1-S wlp (t p )

[0239] in, As of t p The total water production per day, As of t p Total oil production per day.

[0240] In a preferred embodiment of the present invention, when t p =100, S whp (100) = 0.5322, S ohp (100) = 0.4678, S wlp (100) = 0.3091, S olp (100)=0.6909.

[0241] (13) Average oil saturation S o (t p ), average water saturation S w (t p ) is updated, if t is greater than the production time T, go to step (14), otherwise go to step (7);

[0242] Average oil saturation S o (t p ), average water saturation S w (t p ) is calculated as follows:

[0243]

[0244] S w (t p )=1-S o (t p ).

[0245] In a preferred embodiment of the present invention, when t p =100, S o (100) = 0.6872, S w (100)=0.3128.

[0246] (14) Output the results.

[0247] The comparison chart of daily oil production calculation value and actual value is as follows Figure 5 As shown in the figure, the comparison between the calculated value and the actual value of total oil production is shown in Figure 6 As shown in the figure, the saturation changes in the high permeability zone during well production are as follows: Figure 7 shown.

[0248] When imbibition is considered, the error between the calculated and actual total oil production is 0.59%. When imbibition is not considered, the error is 31.74%. Therefore, considering imbibition during water injection production can effectively improve the accuracy of horizontal well production capacity prediction.

[0249] An embodiment of the present invention also provides a computer device, which includes: at least one processor, a memory, and a computer program stored in the memory and executable on the at least one processor, wherein the processor implements the steps of any of the above-mentioned method embodiments when executing the computer program.

[0250] An embodiment of the present invention further provides a computer-readable storage medium, wherein the computer-readable storage medium stores a computer program. When the computer program is executed by a processor, the steps in the above-mentioned method embodiments can be implemented.

[0251] An embodiment of the present invention also provides an information data processing terminal, which is used to provide a user input interface to implement the steps in the above-mentioned method embodiments when executed on an electronic device. The information data processing terminal is not limited to mobile phones, computers, and switches.

[0252] An embodiment of the present invention further provides a server, which is used to provide a user input interface to implement the steps in the above method embodiments when executed on an electronic device.

[0253] An embodiment of the present invention provides a computer program product. When the computer program product is run on an electronic device, the electronic device can implement the steps of the above-mentioned method embodiments when executing the computer program product.

[0254] If the integrated unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the present application implements all or part of the processes in the above-mentioned embodiment method by instructing the relevant hardware through a computer program. The computer program can be stored in a computer-readable storage medium. When the computer program is executed by a processor, it can implement the steps of each of the above-mentioned method embodiments. The computer program includes computer program code, which can be in source code form, object code form, executable file or some intermediate form. The computer-readable medium can at least include: any entity or device that can carry the computer program code to the camera / terminal device, recording medium, computer memory, read-only memory (ROM), random access memory (RAM), electrical carrier signal, telecommunication signal and software distribution medium. For example, a USB flash drive, a mobile hard disk, a magnetic disk or an optical disk.

[0255] In the above embodiments, the description of each embodiment has its own focus. For parts that are not described or recorded in detail in a certain embodiment, reference can be made to the relevant description of other embodiments.

[0256] The above description is only a preferred specific implementation method of the present invention, but the scope of protection of the present invention is not limited thereto. Any modifications, equivalent substitutions and improvements made by any technician familiar with this technical field within the technical scope disclosed by the present invention and within the spirit and principles of the present invention should be covered by the scope of protection of the present invention.

Claims

1. A method for predicting multiphase productivity of horizontal well water injection in tight oil reservoirs, characterized by: The method for predicting the multiphase production capacity of horizontal well water injection in tight oil reservoirs includes: determining various parameters of the oil reservoir and fluid; calculating the formation pressure and saturation after water injection when the water injection process is instantaneously completed; calculating the saturation dynamics during the well soaking and imbibition process; calculating the total production using the saturation field after the well soaking as the initial field, and splitting the oil and water production according to the total production and relative permeability curves; calculating the pressure field during the well opening and production process; calculating the crossflow rate from the low permeability zone of the matrix to the high permeability zone of the fracture, updating the saturation field of each zone, and outputting the results; The method for predicting multiphase productivity of horizontal well water injection in tight oil reservoirs comprises the following steps: Step 1: Determine various parameters of reservoir, fluid and production; Step 2: When the water injection process is completed instantly, the average formation pressure p before the well is shut down is calculated based on the volume balance principle. ai , initial water saturation S in the hyperpermeable zone whi , initial oil saturation S in high permeability zone ohi , initial water saturation S in low permeability zone wli and the initial oil saturation S in the low permeability zone oli ; Step 3: Let the initial number of days of soaking the well be t s =0, initial water saturation S in the high permeability zone during the soaking process whs (0) = S whi , initial oil saturation S in high permeability zone ohs (0) = S ohi , initial water saturation S in the low permeability zone wls (0) = S wli , initial oil saturation S in low permeability zone ols (0) = S oli ; Step 4: Let Δt s =1,t s =t s +1, calculate the tth time in the soaking process s Daily absorption capacity Q im (t s ); Step 5: Update the tth s The water saturation S of the high permeability zone whs (t s ), oil saturation S in high permeability zone ohs (t s ), water saturation S in low permeability zone wls (t s ) and oil saturation S in low permeability zone ols (t s ), if t s Greater than the total soaking time t m , then go to step 6, otherwise return to step 4; Step 6: Let the initial number of days of production be t p =0, initial water saturation S in high permeability zone during well production whp (0) = S whs (t m ), initial oil saturation S in high permeability zone ohp (0) = S ohs (t m ), initial water saturation S in the low permeability zone during well production wlp (0) = S wls (t m ), initial oil saturation S in low permeability zone olp (0) = S ols (t m ), the initial average formation pressure p during well production av (0) = p ai , the initial oil phase crossflow rate Q during well production co (0) = 0, initial water phase crossflow rate Q cw (0) = 0, calculate the initial average water saturation S of all areas during the well production process w (0) and the initial average oil saturation S o (0); Step 7: Let Δt p =1,t p =t p +1, solve the tth p Total daily output q t (t p ); Step 8: Based on the water phase relative permeability curve and the oil phase relative permeability curve, use linear interpolation to obtain the t-th p Average water saturation S before production starts w (t p -1) The corresponding water phase relative permeability k rw (t p ) and oil phase relative permeability k ro (t p ); Step 9: Split the oil and water production according to relative permeability to obtain the t p Tianshui output q w (t p ) and oil production q o (t p ); Step 10: Calculate the pressure drop dp(t p ), and thus calculate the average pressure p av (t p ); Calculate till t p Total oil phase cross-flow rate Q per day co (t p ) and the total water phase cross-flow rate Q cw (t p ); Step 11: water saturation S in the hypertonic zone whp (t p ), oil saturation S in high permeability zone ohp (t p ), water saturation S in low permeability zone wlp (t p ) and oil saturation S in low permeability zone olp (t p ) to update; Step 12: average oil saturation S o (t p ) and average water saturation S w (t p ) is updated. If t is greater than the production time T, the result is output, otherwise return to step 7.

2. The method for predicting multiphase productivity of horizontal well water injection in tight oil reservoirs according to claim 1, characterized in that: The reservoir, fluid and production parameters in step 1 include: reservoir thickness h, reservoir width x e , horizontal well length L w , original formation pressure p i , bottom hole pressure p wf , original oil saturation S oi , initial water saturation S wi , inner zone reservoir permeability k I , inner zone fracture reservoir permeability k IF , outer zone reservoir permeability k O , crossflow coefficient λ, elastic storage volume ratio ω, external reservoir porosity φ O , inner zone matrix porosity φ I , the overall porosity of the inner matrix φ Ib , the porosity of the micro-fracture medium in the inner zone φ IF , the porosity of the micro-fracture medium under the entire inner reservoir φ IFb , comprehensive compression coefficient of inner area c I , comprehensive compression coefficient of outer area c O , number of cracks n F , main fracture permeability k F , main fracture porosity φ F , crack width w F , crack half length x F , wellbore radius r w , comprehensive crack compression coefficient c F , water injection volume V inj , soaking time t m , imbibition diffusion coefficient D, total soaking time t m , production time T, crude oil viscosity μ o , water viscosity μ w , crude oil density ρ o , water density ρ w , crude oil volume coefficient B o , water volume coefficient B w , water compressibility c w , oil compression coefficient c o , bound water saturation S oc , residual oil saturation S wc , water phase relative permeability curve and oil phase relative permeability curve.

3. The method for predicting multiphase productivity of horizontal well water injection in tight oil reservoirs according to claim 1, characterized in that: The average formation pressure p before soaking in step 2 ai , initial water saturation S in the hyperpermeable zone whi , initial oil saturation S in high permeability zone ohi , initial water saturation S in low permeability zone wli and the initial oil saturation S in the low permeability zone oli The calculation formula is as follows: S ohi =1-S whi ; S wli =S wi ; S oli =1-S wli ; Among them, V t =x F hH w is the volume of the inner region, is the average porosity of the reservoir before water injection, V F =n F w F x F h is the volume of the artificial crack, is the proportion of high permeability area after reservoir volume fracturing; The imbibition amount Q in step 4 im (t s ) is calculated as follows: Among them, R0 is the maximum recovery degree, λ is the imbibition intensity; The tth s The water saturation S of the high permeability zone whs (t s ), oil saturation S in high permeability zone ohs (t s ), water saturation S in low permeability zone wls (t s ) and oil saturation S in low permeability zone ols (t s ) is calculated as follows: S ohs (t s )=1-S whs (t s ); S ols (t s )=1-S wls (t s ); in, As of t s Total percolation volume per day.

4. The method for predicting multiphase productivity of horizontal well water injection in tight oil reservoirs according to claim 1, characterized in that: The initial average water saturation S of all areas during the well production process in step 6 w (0) and the initial average oil saturation S o The calculation formula of (0) is as follows: S w (0)=1-S o (0); where, N io = V t S oi φ i / B o , N iw = V t S wi φ i / B w , N iot = N io + (x e - x F ) y e hS oi φ O / B o , N iwt = N iw + (x e - x F ) y e hS wi φ O / B w ; The total output q in step 7 t (t p ) is calculated as follows: in, is the dimensionless pressure, μ m =S w (t p -1)μ w +S o (t p -1)μ o is the average viscosity; Step 9, t p Tianshui output q w (t p ) and oil production q o (t p ) is calculated as follows: q w (t p )=C wp q t (t p ); q o (t p )=C op q t (t p ); in, is the water production coefficient, is the oil production coefficient.

5. The method for predicting multiphase productivity of horizontal well water injection in tight oil reservoirs according to claim 1, characterized in that: The pressure drop dp(t p ) and the average pressure p av (t p ) is calculated as follows: in, As of t p Total oil phase cross-flow rate Q per day co (t p ) and the total water phase cross-flow rate Q cw (t p ) is calculated as follows: The water saturation S in the hypertonic zone in step 11 whp (t p ), oil saturation S in high permeability zone ohp (t p ), water saturation S in low permeability zone wlp (t p ) and oil saturation S in low permeability zone olp (t p ) is calculated as follows: in, As of t p The total water production per day, As of t p Total oil production per day; The average oil saturation S in step 12 o (t p ) and average water saturation S w (t p ) is calculated as follows: S w (t p )=1-S o (t p )。 6. A system for predicting the multiphase productivity of horizontal well water injection in tight oil reservoirs using the method for predicting the multiphase productivity of horizontal well water injection in tight oil reservoirs according to any one of claims 1 to 5, characterized in that: The multiphase productivity prediction system for water injection throughput of horizontal wells in tight oil reservoirs includes: The saturation calculation module is used to determine various parameters of the reservoir and fluid. When the water injection process is completed instantly, the formation pressure and saturation after water injection are calculated, and the saturation dynamics during the soaking and imbibition process are calculated. The oil-water production splitting module is used to calculate the total production using the saturation field after the well is soaked as the initial field, and split the oil-water production according to the total production and relative permeability curves; The saturation field update module is used to calculate the pressure field during the well production process, calculate the crossflow rate from the low permeability area of ​​the matrix to the high permeability area of ​​the fracture, update the saturation field of each area and output the results.

7. A computer device, characterized in that: The computer device includes a memory and a processor, the memory stores a computer program, and when the computer program is executed by the processor, the processor executes the steps of the method for predicting multiphase productivity of horizontal well water injection in tight oil reservoirs according to any one of claims 1 to 5.

8. A computer-readable storage medium storing a computer program, wherein when the computer program is executed by a processor, the processor executes the steps of the method for predicting multiphase productivity of horizontal well water injection in tight oil reservoirs according to any one of claims 1 to 5.

9. An information data processing terminal, characterized in that: The information data processing terminal is installed on an electronic device and provides a user input interface to implement the multiphase productivity prediction system for water injection throughput of horizontal wells in tight oil reservoirs as claimed in claim 6.

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