Fracturing transformation optimization method and device for tight gas glutenite reservoir

Abstract

The invention relates to the technical field of oil field downhole operation, in particular to a tight gas glutenite reservoir fracturing transformation optimization method and device. The method comprises the steps that artificial hydraulic fracture height numerical simulation under different interlayer stress differences and different displacements is carried out on a first stratum basic model of different interbed combinations to obtain a first relation chart, and the displacement of a target stratum during fracturing is determined; performing artificial hydraulic fracture height numerical simulation on the second stratum basic model under different sand adding amounts and average sand ratios to obtain a second relation chart, and determining the sand adding amount when the target stratum is fractured; and performing artificial hydraulic fracture height numerical simulation on the third stratum basic model under different cluster distances or different segment cluster distances to obtain a third relation chart, determining a target stratum cluster or segment and the cluster distance, and completing work area fracturing transformation optimization. The problems that in fracturing construction of a compact gas field at present, no related usable plate is used for guiding fracturing process design such as sand adding scale and cluster spacing, and consequently the fracturing transformation degree is low, and the yield is rapidly decreased are solved.

Description

Technical Field

[0001] The present invention relates to the technical field of oilfield downhole operations, and in particular to a method and device for optimizing the fracturing transformation of a tight gas conglomerate reservoir. Background Art

[0002] At present, the exploration and development technology of tight gas fields still uses the straight / directional well development technology of low permeability gas reservoirs. Reservoir transformation has increased the innovation and optimization of hydraulic sand fracturing technology, but the single well production is low, the decline is fast, and the overall development effect is not ideal.

[0003] Tight gas reservoirs are characterized by ultra-low porosity and low permeability sandy conglomerate formations, characterized by a lack of natural fractures and high heterogeneity. During hydraulic fracturing of tight gas sandy conglomerate reservoirs, fracture propagation patterns are difficult to control, making large-scale stimulation challenging. The presence of gravel can easily lead to fracture distortion and multiple fracture propagation during fracturing, resulting in sand plugging and impairing fracturing effectiveness. Furthermore, artificial hydraulic fractures are often gravel-circling fractures, resulting in high tortuosity, high closure stress, numerous narrow fractures, and uneven proppant placement. Traditional reservoir stimulation techniques struggle to maintain fracture conductivity.

[0004] Tight gas fracturing technology, both domestically and internationally, has entered an era of dense-cut, large-scale volumetric fracturing. Due to the high heterogeneity of tight gas reservoirs, fracturing schemes lack a comprehensive understanding of how to transform high-quality reservoirs outside the wellbore, the scale of tight gas sand addition, and the degree of dense cutting. There are no usable charts to directly guide reservoir transformation construction process design. For non-continuous reservoirs, such as interbedded sand and mud layers, where high-quality reservoirs exist above and below the wellbore, it is difficult to achieve the desired artificial hydraulic fracture height to penetrate the high-quality reservoirs above and below, and the direction of construction process penetration optimization is unclear. In the transformation of tight gas sandy conglomerate reservoirs, it is necessary to optimize cluster spacing and dense cutting for continuous reservoirs to achieve full reservoir transformation, while also employing an extreme sand addition mode. However, effective guidance is lacking on how to achieve the optimal combination of dense cutting and extreme sand addition. Summary of the Invention

[0005] The present invention proposes a method and device for optimizing the fracturing transformation of tight gas conglomerate reservoirs to solve the problems of low fracturing transformation degree and rapid production decline caused by the lack of relevant usable charts to guide the fracturing process design such as sand addition scale and cluster spacing in the current fracturing construction of tight gas fields.

[0006] According to one aspect of the present invention, a method for optimizing fracturing of tight gas conglomerate reservoirs is provided, comprising:

[0007] Establishing a first stratum basic model of different interlayer combinations in the work area, performing numerical simulations of artificial hydraulic fracture heights under different interlayer stress differences and different displacement rates on the first stratum basic model of different interlayer combinations, obtaining a relationship chart of interlayer stress difference, interlayer fracture height, and displacement rate, i.e., a first relationship chart, and determining the displacement rate for fracturing the target stratum based on the first relationship chart;

[0008] Establishing a basic model of the second formation in the work area, numerically simulating the height of artificial hydraulic fractures under different sand addition amounts and average sand ratios on the second basic model, and obtaining a relationship chart of the stimulated volume and fracture conductivity with the sand addition amount, i.e., a second relationship chart. Based on the second relationship chart, the sand addition amount for fracturing the target formation is determined;

[0009] A basic model of the third formation in the work area is established, and numerical simulations of the artificial hydraulic fracture heights under different clusters or different segments and cluster spacings are performed on the basic model of the third formation to obtain a relationship chart of the transformed volume and the transformed volume per meter with the clusters or segments and cluster spacings, i.e., a third relationship chart. Based on the third relationship chart, the clusters or segments and cluster spacings during fracturing of the target layer are determined to complete the fracturing transformation optimization of the work area.

[0010] Preferably, the method for establishing a basic model of the first stratum of different interbed combinations in the work area includes:

[0011] Obtain relevant parameters for establishing the basic model of the first stratum of different interbed combinations in the work area;

[0012] The parameters related to establishing the first basic model of different interbed combinations include at least: Young's modulus, Poisson's ratio, tensile strength, total reservoir thickness and single cluster liquid addition amount;

[0013] According to the relevant parameters for establishing the first basic stratum model of different interbed combinations, the first basic stratum model of different interbed combinations is established.

[0014] Preferably, the different interlayer combinations include: a unidirectional thin interlayer combination and a bidirectional symmetrical thin interlayer combination;

[0015] The unidirectional thin interlayer combination and the bidirectional symmetrical thin interlayer combination respectively include two schemes: the thickness ratio of the sandstone and mudstone interlayers is a first predetermined ratio and a second predetermined ratio.

[0016] Preferably, the first predetermined ratio is 2:1, and the second predetermined ratio is 3:1.

[0017] Preferably, the method for determining the displacement during fracturing of the target layer according to the first relationship diagram includes:

[0018] Obtain the predetermined interlayer stress difference corresponding to the target layer in the work area;

[0019] On the first relationship diagram, the displacement value corresponding to the predetermined interlayer stress difference and the predetermined crack height is found, and the displacement during the fracturing of the target layer should be greater than or equal to the corresponding displacement value.

[0020] Preferably, the method for establishing a basic model of the second stratum in the work area includes:

[0021] Obtain relevant parameters for establishing the basic model of the second stratum in the work area;

[0022] The parameters for establishing the second basic formation model include at least: reservoir thickness, Young's modulus, Poisson's ratio, number of segments, number of clusters, cluster spacing, ground stress, and fluid addition amount;

[0023] A second stratum basic model is established according to the relevant parameters for establishing the second stratum basic model.

[0024] Preferably, the method for determining the amount of sand added during fracturing of the target layer according to the second relationship diagram includes:

[0025] On the second relationship chart, find the sand addition value corresponding to the case where the transformation volume and fracture conductivity meet the requirements at the same time. This sand addition value is the sand addition amount for fracturing the target layer.

[0026] Preferably, the method for establishing a basic model of the third stratum in the work area includes:

[0027] Obtain relevant parameters for establishing the basic model of the third stratum in the work area;

[0028] The parameters for establishing the third basic formation model include at least: reservoir thickness, Young's modulus, Poisson's ratio, number of sections, number of clusters, in situ stress, amount of fluid added, and amount of sand added;

[0029] A third stratum basic model is established according to the relevant parameters for establishing the third stratum basic model.

[0030] Preferably, the method for determining the clusters or segments and cluster spacing during fracturing of the target layer according to the third relationship map includes:

[0031] If the target layer in the work area is single-stage fracturing, the third relationship chart is a chart showing the relationship between the stimulation volume and the stimulation volume per meter and the cluster spacing;

[0032] On the relationship chart of the reformed volume, reformed volume per meter, and cluster spacing, find the corresponding cluster spacing value when both the reformed volume and reformed volume per meter meet the requirements. This cluster spacing value is the cluster spacing during fracturing of the target layer.

[0033] If the target layer in the work area is multi-stage fracturing, the third relationship diagram includes a diagram of the relationship between the stimulated volume and the stage and cluster spacing, and a diagram of the relationship between the stimulated volume per meter and the stage and cluster spacing;

[0034] On the graph of the relationship between the transformed volume and the segment and cluster spacing and the graph of the relationship between the transformed volume per meter and the segment and cluster spacing, find the corresponding cluster spacing value and segment spacing value when the transformed volume and the transformed volume per meter meet the requirements. The cluster spacing value and segment spacing value are the segment and cluster spacing when the target layer is fracturing.

[0035] According to one aspect of the present invention, a device for optimizing the fracturing transformation of a tight gas conglomerate reservoir is provided, comprising:

[0036] a penetration optimization unit for establishing a first basic stratum model of different interlayer combinations in a work area, performing numerical simulations of artificial hydraulic fracture heights under different interlayer stress differences and different displacement rates on the first basic stratum model of different interlayer combinations, obtaining a relationship chart of interlayer stress difference, penetration fracture height, and displacement rate, i.e., a first relationship chart, and determining the displacement rate for fracturing the target stratum based on the first relationship chart;

[0037] A sand addition scale optimization unit is used to establish a basic model of the second formation in the work area, perform numerical simulations of the artificial hydraulic fracture height under different sand addition amounts and average sand ratios on the second formation basic model, and obtain a relationship chart of the stimulated volume and fracture conductivity with the sand addition amount, i.e., a second relationship chart. Based on the second relationship chart, the sand addition amount for fracturing the target formation is determined;

[0038] The dense cutting optimization unit is used to establish a basic model of the third formation in the work area, perform numerical simulation of the artificial hydraulic fracture height under different clusters or different segments and cluster spacing on the third formation basic model, and obtain the relationship chart of the transformed volume and the transformed volume per meter and the clusters or segments and cluster spacing, that is, the third relationship chart. According to the third relationship chart, the clusters or segments and cluster spacing during fracturing of the target layer are determined to complete the fracturing transformation optimization of the work area.

[0039] The present invention has at least the following beneficial effects:

[0040] The present invention proposes a method and device for optimizing the fracturing transformation of tight gas conglomerate reservoirs. By establishing a reservoir transformation construction process map, parameter optimization is performed during fracturing design to guide fracturing construction, thereby enhancing the effective degree of reservoir transformation, increasing single well production, and providing effective technical support for the subsequent development of the block. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] The accompanying drawings herein are incorporated into and constitute a part of the specification. These drawings illustrate embodiments consistent with the present invention and, together with the specification, are used to explain the technical solutions of the present invention.

[0042] Figure 1 A flow chart showing a method for optimizing the fracturing transformation of a tight gas conglomerate reservoir according to an embodiment of the present invention is shown;

[0043] Figure 2 A schematic diagram of a basic model of a first stratum with different interbed combinations according to an embodiment of the present invention is shown;

[0044] Figure 3 A diagram showing the relationship between interlaminar stress difference and through-layer seam height and displacement according to an embodiment of the present invention;

[0045] Figure 4 Figure 3 shows the morphology of artificial hydraulic fractures under different sand addition amounts and average sand ratios obtained through numerical simulation according to an embodiment of the present invention;

[0046] Figure 5 A diagram showing the relationship between the transformation volume, fracture conductivity, and sand addition amount according to an embodiment of the present invention;

[0047] Figure 6 Figure 3 shows the morphology of artificial hydraulic fractures at different cluster spacings obtained through numerical simulation according to an embodiment of the present invention;

[0048] Figure 7 A diagram showing the relationship between the transformation volume and the transformation volume per meter and the cluster spacing according to an embodiment of the present invention;

[0049] Figure 8 Figure 3 shows the morphology of artificial hydraulic fractures at different segments and cluster spacings obtained through numerical simulation according to an embodiment of the present invention;

[0050] Figure 9 A diagram showing the relationship between the reconstruction volume and the segment and cluster spacing according to an embodiment of the present invention;

[0051] Figure 10 A graph showing the relationship between the reconstructed volume per meter and the segment and cluster spacing according to an embodiment of the present invention is shown. DETAILED DESCRIPTION

[0052] Various exemplary embodiments, features, and aspects of the present invention will be described in detail below with reference to the accompanying drawings. The same reference numerals in the accompanying drawings represent elements with the same or similar functions. Although various aspects of the embodiments are shown in the accompanying drawings, the drawings are not necessarily drawn to scale unless otherwise indicated.

[0053] The word “exemplary” is used exclusively herein to mean “serving as an example, example, or illustration.” Any embodiment described herein as “exemplary” is not necessarily to be construed as preferred or advantageous over other embodiments.

[0054] The term "and / or" herein simply describes an association relationship between associated objects, indicating that three relationships can exist. For example, "A and / or B" can represent the existence of three situations: A alone, A and B simultaneously, and B alone. Furthermore, the term "at least one" herein refers to any combination of at least two of any one or more of a plurality of items. For example, "at least one of A, B, and C" can represent any one or more elements selected from the set consisting of A, B, and C.

[0055] In addition, numerous specific details are provided in the following detailed description to better illustrate the present invention. Those skilled in the art will appreciate that the present invention may be practiced without certain specific details. In some instances, methods, means, components, and circuits well known to those skilled in the art have not been described in detail in order to highlight the main points of the present invention.

[0056] Figure 1 A flow chart showing a method for optimizing the fracturing transformation of a tight gas conglomerate reservoir according to an embodiment of the present invention is shown; Figure 2 A schematic diagram of a basic model of a first stratum with different interbed combinations according to an embodiment of the present invention is shown;

[0057] Figure 3 A diagram showing the relationship between interlaminar stress difference and through-layer seam height and displacement according to an embodiment of the present invention; Figure 4 Figure 3 shows the morphology of artificial hydraulic fractures under different sand addition amounts and average sand ratios obtained through numerical simulation according to an embodiment of the present invention; Figure 5 A diagram showing the relationship between the transformation volume, fracture conductivity, and sand addition amount according to an embodiment of the present invention; Figure 6 Figure 3 shows the morphology of artificial hydraulic fractures at different cluster spacings obtained through numerical simulation according to an embodiment of the present invention; Figure 7 A diagram showing the relationship between the transformation volume and the transformation volume per meter and the cluster spacing according to an embodiment of the present invention; Figure 8 Figure 3 shows the morphology of artificial hydraulic fractures at different segments and cluster spacings obtained through numerical simulation according to an embodiment of the present invention; Figure 9 A diagram showing the relationship between the reconstruction volume and the segment and cluster spacing according to an embodiment of the present invention; Figure 10 The relationship between the remodeled volume per meter and the segment and cluster spacing according to an embodiment of the present invention is shown in FIG. Figure 1-10As shown, a method for optimizing the hydraulic fracturing of a tight gas conglomerate reservoir comprises the following steps: Step S01: establishing a basic model of a first formation with different interlayer combinations in a work area, numerically simulating the height of artificial hydraulic fractures under different interlayer stress differences and different displacement rates for the basic model of the first formation with different interlayer combinations, obtaining a relationship chart of the interlayer stress difference, the interlayer fracture height, and the displacement, i.e., a first relationship chart, and determining the displacement during the fracturing of the target layer based on the first relationship chart; Step S02: establishing a basic model of a second formation in the work area, numerically simulating the height of artificial hydraulic fractures under different sand addition amounts and average sand ratios for the basic model of the second formation. Numerical simulation of fracture height is performed to obtain a relationship chart of the transformed volume, fracture conductivity and sand addition amount, i.e., a second relationship chart. Based on the second relationship chart, the sand addition amount during fracturing of the target layer is determined. Step S03: Establish a basic model of the third formation in the work area, perform numerical simulation of artificial hydraulic fracture height under different clusters or different segments and cluster spacing on the third formation basic model, obtain a relationship chart of the transformed volume and the transformed volume per meter and the clusters or segments and cluster spacing, i.e., a third relationship chart. Based on the third relationship chart, the clusters or segments and cluster spacing during fracturing of the target layer are determined to complete the fracturing transformation optimization of the work area.

[0058] The embodiment of the present invention provides a method for optimizing the fracturing transformation of a tight gas conglomerate reservoir, which specifically includes the following steps:

[0059] Step S01: Establish a basic model of the first stratum of different interlayer combinations in the work area, perform numerical simulation of the artificial hydraulic fracture height under different interlayer stress differences and different displacement rates on the basic model of the first stratum of different interlayer combinations, and obtain a relationship chart of the interlayer stress difference, the interlayer fracture height and the displacement, i.e., the first relationship chart. According to the first relationship chart, determine the displacement during fracturing of the target layer.

[0060] In the embodiment of the present invention, when optimizing the penetration, it is necessary to combine geological and logging information, target the characteristics of tight gas conglomerate reservoirs, clarify the reservoir's physical properties, brittleness, geostress and other geological parameters, and combine the influencing factors such as interbeds of sand and mud. Through numerical simulation, based on different interbed patterns, interlayer stress differences and the changing trends of fracture height under different displacement parameters, a relationship chart between different reservoirs, interlayer stress differences, displacement rates and other parameters and penetration fracture height is established.

[0061] In the present invention, the method for establishing a basic model of the first stratum of different interlayer combinations in a work area includes: obtaining relevant parameters for establishing the basic model of the first stratum of different interlayer combinations in the work area; wherein the relevant parameters for establishing the basic model of the first stratum of different interlayer combinations include at least: Young's modulus, Poisson's ratio, tensile strength, total reservoir thickness and single cluster liquid addition amount; based on the relevant parameters for establishing the basic model of the first stratum of different interlayer combinations, the basic model of the first stratum of different interlayer combinations is established.

[0062] In the embodiment of the present invention, basic models of the first stratum with different interbed combinations are designed to simulate the propagation height of artificial hydraulic fractures generated by the initiation of a single cluster of fractures in the middle of a sandy conglomerate reservoir in different interbed combinations. The basic parameters used are shown in Table 1 below:

[0063] Table 1: Parameters of the basic model for the first stratum of different interbed combinations

[0064]

[0065] In the present invention, the different interlayer combinations include: a unidirectional thin interlayer combination and a bidirectional symmetrical thin interlayer combination;

[0066] The unidirectional thin interlayer combination and the bidirectional symmetrical thin interlayer combination respectively include two schemes: the thickness ratio of the sandstone and mudstone interlayers is a first predetermined ratio and a second predetermined ratio.

[0067] In the present invention, the first predetermined ratio is 2:1, and the second predetermined ratio is 3:1.

[0068] In the embodiment of the present invention, two types of interlayer combinations are set for the cross-layer simulation, with a total of four schemes, including: 1. One-way thin interlayer combination, including two schemes with a sandstone and mudstone interlayer thickness ratio of 2:1 and 3:1; 2. Two-way symmetrical thin interlayer combination, including two schemes with a sandstone and mudstone interlayer thickness ratio of 2:1 and 3:1. The schematic diagram of the first stratum basic model corresponding to the four schemes is shown as follows: Figure 2 As shown, in Figure 2 In the figure, Figure a shows a scheme with a 2:1 thickness ratio of sandstone and mudstone interlayers in a unidirectional thin interlayer combination, Figure b shows a scheme with a 3:1 thickness ratio of sandstone and mudstone interlayers in a unidirectional thin interlayer combination, Figure c shows a 2:1 thickness ratio of sandstone and mudstone interlayers in a bidirectional symmetrical thin interlayer combination, and Figure d shows a 3:1 thickness ratio of sandstone and mudstone interlayers in a bidirectional symmetrical thin interlayer combination.

[0069] In the present invention, the method for determining the displacement during fracturing of the target layer based on the first relationship map includes: obtaining a predetermined interlayer stress difference corresponding to the target layer in the work area; finding the displacement value corresponding to the predetermined interlayer stress difference and the predetermined crack height on the first relationship map, and the displacement during fracturing of the target layer should be greater than or equal to the corresponding displacement value.

[0070] In the embodiment of the present invention, by performing relevant numerical simulations to simulate different interlayer stress differences and construction displacement combinations, a set of relationship charts of interlayer stress differences, displacement and other parameters with interlayer joint height under different interlayer conditions are obtained, namely the first relationship chart, as shown in FIG. Figure 3 shown.

[0071] The relationship chart reveals the relationship between the displacement parameter and the height of the through-layer joint under different interlayer stress differences. Figure 3 It can be seen that when the displacement (construction displacement) is greater than 14m 3 At a rate of 1.5 t / min, the penetration capacity of artificial hydraulic fractures during expansion was significantly enhanced, and the fracture height was significantly increased. Different interlayer pattern combinations reveal that mudstone interlayers weaken the penetration capacity of fractures under stress differential conditions. Therefore, in the presence of multiple thin interlayers, the construction displacement should be increased as much as possible to achieve the ideal fracture layer height.

[0072] If the target layer's corresponding inter-layer combination mode is Figure 3 Figure a in the figure shows that the thickness ratio of sandstone and mud interlayer in the unidirectional thin interlayer combination is 2:1, and the predetermined interlayer stress difference corresponding to the target layer is 5. According to Figure 3 In Figure a, find the predetermined crack height that meets the requirements when the interlayer stress difference is 5. For example, when the predetermined crack height is 52m, the corresponding construction displacement is 14m. 3 / min, therefore, the construction displacement during fracturing of the target layer should be greater than or equal to 14m 3 / min.

[0073] Step S02: Establish a basic model of the second formation in the work area, perform numerical simulation of the artificial hydraulic fracture height under different sand addition amounts and average sand ratios on the second basic model, and obtain a relationship chart of the stimulated volume and fracture conductivity with the sand addition amount, i.e., the second relationship chart. Based on the second relationship chart, determine the sand addition amount for fracturing the target formation.

[0074] In the embodiment of the present invention, for the purpose of optimizing the stimulation volume, when optimizing the sand addition scale in tight gas-sand conglomerate gas reservoirs, it is necessary to obtain the effective stimulation volume of artificial hydraulic fractures under different sand addition scales through numerical simulation, and then obtain the relationship between the sand addition scale and the effective stimulation volume, establish a sand addition chart (second relationship chart), and thus determine the feasible optimal limit sand addition scale (sand addition amount).

[0075] In the present invention, the method for establishing a second formation basic model of the work area includes: obtaining relevant parameters for establishing the second formation basic model of the work area; wherein the relevant parameters for establishing the second formation basic model include at least: reservoir thickness, Young's modulus, Poisson's ratio, number of segments, number of clusters, cluster spacing, ground stress and liquid addition amount; and establishing the second formation basic model based on the relevant parameters for establishing the second formation basic model.

[0076] The results of the flow conductivity of the seams of the present invention are shown in Table 3 below:

[0077] Table 3: Sand addition parameter settings and simulation results

[0078]

[0079] The crack morphology corresponding to different sand addition amounts obtained by numerical simulation is as follows Figure 4 shown.

[0080] In the present invention, the method for determining the amount of sand added during the target layer fracturing based on the second relationship diagram includes: finding, on the second relationship diagram, a corresponding amount of sand added when both the transformed volume and the fracture conductivity meet the requirements, and the amount of sand added is the amount of sand added during the target layer fracturing.

[0081] In the embodiment of the present invention, a sand adding plate, i.e., a second relationship plate, is established according to the numerical simulation results. Figure 5 As shown in FIG, the second relationship diagram reveals the relationship between the fracturing stimulation volume, fracture conductivity and sand addition amount for tight conglomerate gas reservoirs.

[0082] Depend on Figure 5 It can be seen that the fracturing volume is proportional to the amount of sand added. The fracture conductivity will reach a plateau when the amount of sand added reaches 100 cubic meters. When the amount of sand added reaches 140m 3 When the sand ratio is 16.7%, the conductivity reaches the maximum value, and when it reaches 160m 3 After that, it will continue to decrease. When the amount of sand added is 200m 3 When , the fracturing stimulation volume reaches the highest, but the conductivity will drop to below 12. Therefore, when determining the amount of sand added, the fracturing stimulation volume and conductivity should be comprehensively considered, and the corresponding amount of sand added should be selected when both meet the requirements, such as the value at or near the intersection of the stimulation volume and conductivity curves. Figure 5 When the amount of sand added is 160m 3 When the corresponding transformation volume and conductivity values ​​are relatively high and can meet the requirements, the amount of sand added during the target layer fracturing should be 160m 3 .

[0083] Step S03: Establish a basic model of the third formation in the work area, perform numerical simulation of the artificial hydraulic fracture height under different clusters or different segments and cluster spacing on the third formation basic model, and obtain a relationship chart of the transformed volume and the transformed volume per meter with the clusters or segments and cluster spacing, i.e., the third relationship chart. Based on the third relationship chart, determine the clusters or segments and cluster spacing during fracturing of the target layer, and complete the fracturing transformation optimization of the work area.

[0084] In this embodiment of the present invention, when optimizing dense fracturing technology for tight gas conglomerate reservoirs, a basic model of the third formation is constructed. Numerical simulations are then used to optimize the design of different cluster spacings, or combinations of segment and cluster spacings. Taking into account the interference of fractures and stresses, the trends of cluster spacings, or segments and cluster spacings, and the fracturing volume are determined to maximize the fracturing volume. A chart is then created to optimize the fracturing volume.

[0085] In the present invention, the method for establishing a basic model of the third formation in the work area includes: obtaining relevant parameters for establishing the basic model of the third formation in the work area; wherein the relevant parameters for establishing the basic model of the third formation include at least: reservoir thickness, Young's modulus, Poisson's ratio, number of sections, number of clusters, ground stress, liquid addition amount and sand addition amount; and establishing the basic model of the third formation based on the relevant parameters for establishing the basic model of the third formation.

[0086] In the present invention, the method for determining the cluster or segment and cluster spacing during the fracturing of the target layer according to the third relationship map includes: if the target layer in the work area is a single-stage fracturing, the third relationship map is a transformation volume and transformation volume per meter and cluster spacing relationship map; on the transformation volume and transformation volume per meter and cluster spacing relationship map, the cluster spacing value corresponding to the case where the transformation volume and transformation volume per meter meet the requirements at the same time is found, and the cluster spacing value is the cluster spacing during the fracturing of the target layer; if the target layer in the work area is multi-stage fracturing, the third relationship map includes a transformation volume and segment and cluster spacing relationship map and a transformation volume per meter and segment and cluster spacing relationship map; on the transformation volume and segment and cluster spacing relationship map and transformation volume per meter and segment and cluster spacing relationship map, the cluster spacing value and segment spacing value corresponding to the case where the transformation volume and transformation volume per meter meet the requirements at the same time are found, and the cluster spacing value and segment spacing value are the segment and cluster spacing during the fracturing of the target layer.

[0087] In the embodiment of the present invention, for single-stage fracturing, a third formation basic model is designed for cluster spacing optimization. The propagation height of the artificial hydraulic fracture generated by fracturing in the middle of the sandstone conglomerate reservoir with different cluster spacings is simulated. The basic parameters used are shown in Table 4 below:

[0088] Table 4: Parameters for establishing the third formation basic model for cluster spacing optimization

[0089]

[0090] The cluster spacing simulation scheme settings and the transformation volume and transformation volume per meter obtained through simulation are shown in Table 5 below:

[0091] Table 5: Cluster spacing parameter settings and simulation results

[0092]

[0093] The crack morphology corresponding to different cluster spacings obtained by numerical simulation is as follows Figure 6 As shown; the cluster spacing diagram established based on the numerical simulation results, that is, the third relationship diagram, as shown Figure 7 As shown in , it reveals that the fracturing stimulation volume first increases and then decreases with the cluster spacing, and the stimulation volume per meter is inversely proportional to the cluster spacing. Figure 6 It can be seen from the above that when the cluster spacing is less than or equal to 10m, the minimum horizontal principal stress S h The increase is larger than that before fracturing, which will lead to the arrest of the middle fracture. The volume of the third cluster of fractures is only 4.3m 3 (10m cluster spacing), 4.5m 3 (5m cluster spacing), resulting in uneven crack reformation. Figure 7 It can be seen that when the cluster spacing gradually increases, the stimulation volume per meter decreases sharply, while the overall fracturing stimulation volume increases. Under the premise of ensuring the overall fracturing stimulation volume, the stimulation volume per meter should not be too small. Therefore, the corresponding cluster spacing is selected when both requirements are met; for example, the value is taken at or near the intersection of the stimulation volume and the stimulation volume per meter curve. Figure 7 In the figure, when the cluster spacing is 10, the corresponding stimulation volume and stimulation volume per meter are in the range of 200-210, which can meet the requirements. A cluster spacing less than 10 meters may lead to increased stress and uneven stimulation. A cluster spacing exceeding 10 meters may result in too small stimulation per meter. Therefore, it is finally determined that the cluster spacing for fracturing the target layer should be 10m.

[0094] In the embodiment of the present invention, for multi-stage fracturing, a third basic formation model is designed to optimize the combination of stage and cluster spacing. The propagation height of the artificial hydraulic fracture generated by fracturing in the middle of the conglomerate reservoir with different stage and cluster spacing is simulated. The basic parameters used are shown in Table 6 below:

[0095] Table 6: Parameters for establishing the third formation basic model for optimizing segment and cluster spacing

[0096]

[0097] The simulation scheme settings for segment and cluster spacing, as well as the transformation volume and transformation volume per meter obtained through simulation are shown in Table 7 below:

[0098] Table 7: Segment and cluster spacing parameter settings and simulation results

[0099]

[0100] The crack morphology corresponding to different segments and cluster spacing obtained by numerical simulation is as follows Figure 8 As shown in the figure; the transformation volume and segment and cluster spacing combination chart established based on the numerical simulation results, that is, the third relationship chart, as shown in the figure. Figure 9As shown; and the established per-meter transformation volume and segment, cluster spacing combination chart, that is, the third relationship chart, as shown Figure 10 As shown. Figure 9 It can be seen that when the segment spacing is greater than or equal to 15m, the fracturing stimulation volume shows a downward trend, and when the segment spacing is slightly smaller than the cluster spacing, the fracturing stimulation volume is larger. Figure 10 It can be seen that when the optimization target becomes the transformation volume per meter, the segment and cluster spacing combination chart shows a clearer pattern. The transformation volume per meter decreases with the increase of segment spacing, while a smaller cluster spacing produces a higher transformation volume per meter. Figure 9 In the example, when the segment spacing is 15m and the cluster spacing is 25, the corresponding transformation volume is the best, but in Figure 10 In the figure, when the segment spacing is 10 and the cluster spacing is 15, the corresponding stimulation volume per meter is the best. Under the premise of ensuring the overall fracturing stimulation volume, the stimulation volume per meter should not be too small. Therefore, the segment and cluster spacing corresponding to the conditions where both requirements are met are selected.

[0101] If a cluster spacing curve with the same value is found in the combination chart of stimulation volume and segment and cluster spacing and the combination chart of stimulation volume per meter and segment and cluster spacing, and its corresponding maximum stimulation volume and maximum stimulation volume per meter both meet the requirements, then the cluster spacing value of this curve is the cluster spacing during target layer fracturing; and if the segment spacing value corresponding to a point on this same cluster spacing curve meets the requirements in the combination chart of stimulation volume and segment and cluster spacing and the combination chart of stimulation volume per meter and segment and cluster spacing, then the segment spacing value corresponding to this point is the segment spacing at the target layer pressure.

[0102] like Figure 9 and Figure 10 In the curve with cluster spacing of 20, the transformation volume and segment and cluster spacing combination chart ( Figure 9 ) and the combined chart of the transformed volume per meter and the segment and cluster spacing ( Figure 10 ), the corresponding maximum transformation volume is 456.7, and the maximum transformation volume per meter is 1.74, both of which meet the requirements. Therefore, the cluster spacing value of the curve is 20, which is the cluster spacing when the target layer is fracturing; and on the curve corresponding to the cluster spacing of 20, the point with a segment spacing of 15 corresponds to a transformation volume of 456.7, and the corresponding transformation volume per meter is 1.7, both of which meet the requirements. Therefore, the segment spacing when the target layer is fracturing is 15.

[0103] In the embodiment of the present invention, the transformation method of tight gas horizontal wells mostly adopts the open hole completion staged fracturing process, which has poor effect. The reason is that the fracture spacing of this process is too large, which limits the reservoir transformation volume, the fracture-controlled reserves of a single well are limited, and the low sand addition and low fluid addition rates cannot form effective long fractures and complex fracture networks due to the restriction of gravel on fracture expansion. In actual construction, taking the adjacent well A in a certain work area as an example, conventional technical means are used for fracturing construction. The horizontal section length of this well is 1135m, the number of fracturing stages is 12, the average fracture spacing reaches 95m, and the sand addition intensity is 0.90m 3 / m, liquid addition intensity 16.77m 3 / m, resulting in a low degree of stimulation. Based on the previous understanding of the limitations of open-hole completion fracturing, a neighboring well, B, applied a cementing composite bridge plug fracturing process. This process used a composite stimulation process of slickwater and guar gum fracturing fluid (slickwater ratio 25.3%) to create complex fractures in the reservoir. This increased the intensity of sand and fluid addition during fracturing, further expanding the stimulation volume and achieving good stimulation results. The daily gas production after fracturing was 12.6*104m 3 / d. The adjacent well C increased the transformation volume by adopting the cementing dense cutting volume fracturing process and achieved good results, which confirmed the feasibility of the transformation idea. Compared with the open hole completion fracturing process, the casing completion increased the test gas production by 17.5% and the gas production intensity by 56.4%. Well D implemented the fracturing transformation optimization method of the present invention. The horizontal section was divided into three parts for targeted differentiated optimization design of the fracturing segment cluster. The displacement, sand addition amount, and segment and cluster spacing parameters during fracturing were determined by the method of the present invention. The horizontal section of the whole well was divided into 22 segments and 53 clusters. The design adopted segmented clustered composite bridge plug casing dense cutting fracturing, combined with temporary plugging construction technology, and used soluble bridge plugs as segmentation tools. The fracturing fluid used guar gum and conventional slick water. The proppant used was 70-140 mesh powdered ceramic and 40-70 mesh ceramsite (2:8). The perforation method used was equal aperture with flow limiting perforation, with 32 to 48 holes per segment, perforation density of 16 holes / m, and displacement of 14 to 16m 3 / min, sand volume 38~190m 3 , liquid volume 540~2450m 3 High sand and fluid addition rates are used to achieve high reservoir transformation volume and high production. After fracturing, the well underwent preliminary gas testing, and the open flow rate reached 106*104m 3 / d. Compared with the gas test results of adjacent wells, the single well production is estimated to have increased by approximately three times. The gas test results indicate that the fracturing of this well achieved good reservoir stimulation and significant production increases, demonstrating the success of this fracturing stimulation technology innovation and validating the effectiveness of the present invention.

[0104] It can be understood that the above-mentioned various method embodiments mentioned in the present invention can be combined with each other to form combined embodiments without violating the principle logic. Due to space limitations, the present invention will not elaborate on them.

[0105] The execution subject of the tight gas sandy conglomerate reservoir fracturing and transformation optimization method may be a tight gas sandy conglomerate reservoir fracturing and transformation optimization device. For example, the tight gas sandy conglomerate reservoir fracturing and transformation optimization method may be executed by a terminal device, a server, or other processing device, wherein the terminal device may be a user equipment (UE), a mobile device, a user terminal, a terminal, a cellular phone, a cordless phone, a personal digital assistant (PDA), a handheld device, a computing device, an in-vehicle device, a wearable device, etc. In some possible implementations, the tight gas sandy conglomerate reservoir fracturing and transformation optimization method may be implemented by a processor calling computer-readable instructions stored in a memory.

[0106] Those skilled in the art will understand that in the above-mentioned method of the specific implementation method, the writing order of each step does not mean a strict execution order and does not constitute any limitation on the implementation process. The specific execution order of each step should be determined by its function and possible internal logic.

[0107] The present invention also provides a tight gas sandstone reservoir fracturing transformation optimization device, comprising: a penetration optimization unit, used to establish a first formation basic model of different interlayer combinations in a work area, and perform numerical simulation of artificial hydraulic fracture height under different interlayer stress differences and different displacements on the first formation basic model of different interlayer combinations, to obtain a relationship chart of interlayer stress difference, penetration fracture height and displacement, i.e., a first relationship chart, and determine the displacement during fracturing of the target layer according to the first relationship chart; a sand addition scale optimization unit, used to establish a second formation basic model of the work area, and perform numerical simulation of artificial hydraulic fracture height under different interlayer stress differences and different displacements on the second formation basic model The artificial hydraulic fracture height is numerically simulated to obtain the relationship between the transformation volume and the fracture conductivity and the amount of sand added, that is, the second relationship diagram. According to the second relationship diagram, the amount of sand added during the fracturing of the target layer is determined; the dense cutting optimization unit is used to establish a basic model of the third formation in the work area, and numerically simulate the artificial hydraulic fracture height under different clusters or different segments and cluster spacings on the third formation basic model to obtain the relationship between the transformation volume and the transformation volume per meter and the cluster or segment and cluster spacing, that is, the third relationship diagram. According to the third relationship diagram, the cluster or segment and cluster spacing during the fracturing of the target layer are determined to complete the fracturing transformation optimization of the work area.

[0108] In some embodiments, the functions or modules and units included in the device provided by the embodiment of the present invention can be used to execute the method described in the above method embodiment. Its specific implementation can refer to the description of the above method embodiment. For the sake of brevity, it will not be repeated here.

[0109] The existing construction technology for tight gas conglomerate reservoir reconstruction currently faces the following challenges in improving the reconstruction effect: 1. For non-continuous reservoirs, such as interbedded sand and mud layers, with high-quality reservoirs above and below the wellbore, it is difficult to achieve the desired artificial hydraulic fracture height to penetrate the high-quality reservoirs above and below, and the direction of layer penetration optimization in the construction technology is unclear; 2. During the tight gas conglomerate reservoir reconstruction process, it is necessary to optimize the cluster spacing of the continuous reservoir, adopt a dense cutting method to fully transform the reservoir, and adopt an extreme sand addition mode. However, there is a lack of effective guidance on how to achieve the reasonable optimization of dense cutting and extreme sand addition.

[0110] The present invention constructs a three-dimensional multi-hydraulic fracture expansion numerical simulation based on the displacement discontinuity method and the finite volume method for complete fluid-solid coupling, establishes a construction process diagram, that is, a relationship diagram, and adopts a design method that combines layer penetration, extreme sand addition, and intensive cutting for tight gas and conglomerate gas reservoirs. Through the established reservoir transformation construction process diagram, parameters are optimized during fracturing design, thereby realizing a standardized tight gas and conglomerate reservoir transformation design process and template, optimizing the existing fracturing construction process design method, and effectively guiding fracturing construction.

[0111] The present invention solves the problem of rapid production decline in traditional tight gas conglomerate horizontal wells and the difficulty in effectively utilizing proven reserves. It also forms a set of optimization methods for dense-cut large-scale volume fracturing schemes for tight conglomerate reservoirs, enhances the effective transformation of the reservoir, increases the production of single wells, and provides effective technical support for the subsequent development of the block.

[0112] While various embodiments of the present invention have been described above, the above descriptions are intended to be illustrative, non-exhaustive, and not limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments. The terminology used herein is selected to best explain the principles of the embodiments, their practical applications, or technological improvements in the marketplace, or to enable others skilled in the art to understand the embodiments disclosed herein.

Claims

1. A method for optimizing the fracturing transformation of tight gas conglomerate reservoirs, characterized in that: include: Establishing a first stratum basic model of different interlayer combinations in the work area, performing numerical simulations of artificial hydraulic fracture heights under different interlayer stress differences and different displacement rates on the first stratum basic model of different interlayer combinations, obtaining a relationship chart of interlayer stress difference, interlayer fracture height, and displacement rate, i.e., a first relationship chart, and determining the displacement rate for fracturing the target stratum based on the first relationship chart; Establishing a basic model of the second formation in the work area, numerically simulating the height of artificial hydraulic fractures under different sand addition amounts and average sand ratios on the second basic model, and obtaining a relationship chart of the stimulated volume and fracture conductivity with the sand addition amount, i.e., a second relationship chart. Based on the second relationship chart, the sand addition amount for fracturing the target formation is determined; A basic model of the third formation in the work area is established, and numerical simulations of the artificial hydraulic fracture heights under different clusters or different segments and cluster spacings are performed on the basic model of the third formation to obtain a relationship chart of the transformed volume and the transformed volume per meter with the clusters or segments and cluster spacings, i.e., a third relationship chart. Based on the third relationship chart, the clusters or segments and cluster spacings during fracturing of the target layer are determined to complete the fracturing transformation optimization of the work area.

2. The method for optimizing the fracturing transformation of tight gas conglomerate reservoirs according to claim 1, characterized in that: The method for establishing a basic model of the first stratum of different interbed combinations in a work area comprises: Obtain relevant parameters for establishing the basic model of the first stratum of different interbed combinations in the work area; The parameters related to establishing the first basic formation model of different interbed combinations include at least: Young's modulus, Poisson's ratio, tensile strength, total reservoir thickness and single cluster liquid addition amount; According to the relevant parameters for establishing the first basic stratum model of different interbed combinations, the first basic stratum model of different interbed combinations is established.

3. The method for optimizing the fracturing transformation of tight gas conglomerate reservoirs according to claim 2, characterized in that: The different interlayer combinations include: a unidirectional thin interlayer combination and a bidirectional symmetrical thin interlayer combination; The unidirectional thin interlayer combination and the bidirectional symmetrical thin interlayer combination respectively include two schemes: the thickness ratio of the sandstone and mudstone interlayers is a first predetermined ratio and a second predetermined ratio.

4. The method for optimizing the tight gas conglomerate reservoir fracturing according to claim 3, characterized in that: The first predetermined ratio is 2:1, and the second predetermined ratio is 3:

1.

5. The method for optimizing the tight gas conglomerate reservoir fracturing according to claim 1, characterized in that: The method for determining the displacement during fracturing of the target layer according to the first relationship diagram includes: Obtain the predetermined interlayer stress difference corresponding to the target layer in the work area; On the first relationship diagram, the displacement value corresponding to the predetermined interlayer stress difference and the predetermined crack height is found, and the displacement during the fracturing of the target layer should be greater than or equal to the corresponding displacement value.

6. The method for optimizing the tight gas conglomerate reservoir fracturing according to claim 1, characterized in that: The method for establishing a basic model of the second stratum in the work area comprises: Obtain relevant parameters for establishing the basic model of the second stratum in the work area; The parameters for establishing the second basic formation model include at least: reservoir thickness, Young's modulus, Poisson's ratio, number of segments, number of clusters, cluster spacing, ground stress, and fluid addition amount; A second stratum basic model is established according to the relevant parameters for establishing the second stratum basic model.

7. The method for optimizing the tight gas conglomerate reservoir fracturing according to claim 1, characterized in that: According to the second relationship diagram, a method for determining the amount of sand added during fracturing of the target layer includes: On the second relationship chart, find the sand addition value corresponding to the case where the transformation volume and fracture conductivity meet the requirements at the same time. This sand addition value is the sand addition amount for fracturing the target layer.

8. The method for optimizing the tight gas conglomerate reservoir fracturing according to claim 1, characterized in that: The method for establishing a basic model of the third stratum in the work area comprises: Obtain relevant parameters for establishing the basic model of the third stratum in the work area; The parameters for establishing the third basic formation model include at least: reservoir thickness, Young's modulus, Poisson's ratio, number of sections, number of clusters, in situ stress, amount of fluid added, and amount of sand added; A third stratum basic model is established according to the relevant parameters for establishing the third stratum basic model.

9. The method for optimizing the tight gas conglomerate reservoir fracturing according to claim 1, characterized in that: The method for determining the clusters or segments and cluster spacing during fracturing of the target layer according to the third relationship map includes: If the target layer in the work area is single-stage fracturing, the third relationship chart is a chart showing the relationship between the stimulation volume and the stimulation volume per meter and the cluster spacing; On the relationship chart of the reformed volume, reformed volume per meter, and cluster spacing, find the corresponding cluster spacing value when both the reformed volume and reformed volume per meter meet the requirements. This cluster spacing value is the cluster spacing during fracturing of the target layer. If the target layer in the work area is multi-stage fracturing, the third relationship diagram includes a diagram of the relationship between the stimulated volume and the stage and cluster spacing, and a diagram of the relationship between the stimulated volume per meter and the stage and cluster spacing; On the graph of the relationship between the transformed volume and the segment and cluster spacing and the graph of the relationship between the transformed volume per meter and the segment and cluster spacing, find the corresponding cluster spacing value and segment spacing value when the transformed volume and the transformed volume per meter meet the requirements. The cluster spacing value and segment spacing value are the segment and cluster spacing when the target layer is fracturing.

10. A device for optimizing the fracturing transformation of tight gas conglomerate reservoirs, characterized in that: include: a penetration optimization unit for establishing a first basic stratum model of different interlayer combinations in a work area, performing numerical simulations of artificial hydraulic fracture heights under different interlayer stress differences and different displacement rates on the first basic stratum model of different interlayer combinations, obtaining a relationship chart of interlayer stress difference, penetration fracture height, and displacement rate, i.e., a first relationship chart, and determining the displacement rate for fracturing the target stratum based on the first relationship chart; A sand addition scale optimization unit is used to establish a basic model of the second formation in the work area, perform numerical simulations of the artificial hydraulic fracture height under different sand addition amounts and average sand ratios on the second formation basic model, and obtain a relationship chart of the stimulated volume and fracture conductivity with the sand addition amount, i.e., a second relationship chart. Based on the second relationship chart, the sand addition amount for fracturing the target formation is determined; The dense cutting optimization unit is used to establish a basic model of the third formation in the work area, perform numerical simulation of the artificial hydraulic fracture height under different clusters or different segments and cluster spacing on the third formation basic model, and obtain the relationship chart of the transformed volume and the transformed volume per meter and the clusters or segments and cluster spacing, that is, the third relationship chart. According to the third relationship chart, the clusters or segments and cluster spacing during fracturing of the target layer are determined to complete the fracturing transformation optimization of the work area.

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