A method for reorganizing layer series of a multilayer series oil reservoir developed by water injection

Abstract

The present application relates to a kind of multilayer series oil reservoir water injection development layer series reorganization method, obtains well bottom flow pressure when oil layer is separately produced;Pressure loss of fluid is calculated from lower oil layer position to upper oil layer position;Well bottom flow pressure pressure difference between lower oil layer and upper oil layer is compared with pressure loss, the production pressure difference when oil layer is separately produced is corrected to the production pressure difference when two layers are combined, and then the corrected well bottom flow pressure is obtained;Each oil layer flow and total flow are calculated by the corrected well bottom flow pressure;Total flow and the relationship chart of different flow coefficient ratio under combined production vertical distance are drawn;Flow loss amplitude limit is determined according to the minimum oil layer distance and economic benefit, and combined production limit flow is obtained;According to the relationship chart of total flow and different flow coefficient ratio under combined production vertical distance and combined production limit flow, flow coefficient ratio and combined production vertical distance limit relationship chart are determined, whether lower oil layer and upper oil layer can be combined is determined, and the present application provides theoretical basis and guidance.

Description

Technical Field

[0001] This invention relates to the field of oilfield development technology, and specifically to a method for reorganizing multi-layered reservoirs through water injection development. Background Technology

[0002] The Yanchang Oilfield is located in the southeastern part of the Ordos Basin, with its western region featuring well-developed multi-layered reservoirs. During the water injection development of these multi-layered sandstone reservoirs, significant differences in physical and fluid properties exist between the vertically aligned layers, leading to prominent inter-layer contradictions. Due to a lack of clarity regarding the nature of these inter-layer contradictions, the reorganization of the development stratigraphic system often follows several broad principles without specific quantitative principles and methods, directly impacting the effectiveness of water injection development.

[0003] To improve the effectiveness of water injection development in multi-layer reservoirs, alleviating inter-layer conflicts is crucial. Appropriate bottomhole flowing pressure for different reservoirs is an effective method to improve water injection development in multi-layer reservoirs. Appropriate bottomhole flowing pressure can reduce the impact of inter-layer conflicts on the development effect of each reservoir layer, leading to higher reservoir recovery.

[0004] The study on reasonable bottomhole flowing pressure in oil reservoirs mainly focuses on the impact of the flow coefficient range and reservoir distance on the development effect of multi-layer oil reservoirs, and on understanding the essential contradictions of syndicated oil reservoirs. Based on the theories of seepage mechanics and fluid mechanics, calculation methods for the production capacity of each sub-layer and the total production capacity of oil wells in syndicated oil wells are derived for each oil reservoir. This method is applicable to the general calculation method of multi-layer oil reservoirs with similar sedimentary environments under water injection development conditions. Through the production capacity calculation method of syndicated oil reservoirs, a simple and clear production capacity-flow coefficient range and reservoir distance relationship chart can be drawn, allowing for intuitive judgment of the flow coefficient range and reservoir distance boundaries of different oil reservoirs, and guiding the formulation of multi-layer oil reservoir development policies. Summary of the Invention

[0005] The present invention aims to address the above-mentioned problems by proposing a method for reorganizing the strata in the water injection development of multi-layered oil reservoirs.

[0006] The technical solution of this invention is as follows:

[0007] A method for reorganizing the strata in water injection development of multi-layered oil reservoirs, the method is as follows:

[0008] To obtain the bottomhole flowing pressure when the oil reservoir is producing independently;

[0009] Calculate the pressure loss of the fluid flowing from the lower oil layer to the upper oil layer;

[0010] The bottomhole flowing pressure difference and pressure loss between the lower and upper oil layers are compared, and the production pressure difference when the oil layer is producing alone is corrected to the production pressure difference when the two layers are produced together, thus obtaining the corrected bottomhole flowing pressure.

[0011] The flow rates of each oil layer and the total flow rate were obtained by correcting the bottom hole flowing pressure calculation.

[0012] Plot a graph showing the relationship between total flow rate and vertical distance of combined mining operations under different flow coefficient ratios;

[0013] The limit of flow loss is determined based on the minimum inter-oil layer distance and economic benefits, and the limit flow of combined production is obtained.

[0014] Based on the relationship chart between total flow rate and vertical distance between combined mining operations under different flow coefficient ratios, and the limit flow rate of combined mining operations, determine the relationship chart between flow coefficient ratio and vertical distance between combined mining operations, and determine whether the lower oil layer and the upper oil layer can be combined for mining.

[0015] The calculation process for obtaining the bottomhole flowing pressure when the oil reservoir is producing independently is as follows:

[0016]

[0017] In the formula: p wf ρ is the bottom hole flowing pressure, MPa; d is the wellbore diameter, m; ρ is the fluid density, 10 3 kg / m 3 M is the fluid collection index, m 3 / d·MPa; N is the production pressure difference, MPa;

[0018] in,

[0019]

[0020] Where: k is the effective permeability of the oil layer, mD; h is the effective thickness of the oil layer, m; μ is the fluid viscosity, mPa·s; B is the volume coefficient, dimensionless; r e R is the fuel supply radius, in meters (m); w p is the wellbore radius, in meters. e ρ is the formation pressure, MPa; G is the starting pressure gradient, MPa / m.

[0021] The calculation process for the pressure loss of the fluid flowing from the lower oil layer to the upper oil layer is as follows:

[0022]

[0023] Where: g is the acceleration due to gravity, N / kg; H is the vertical distance between the two mining operations, m;

[0024] △p 损失 This represents the pressure loss of fluid flowing from the lower oil layer to the upper oil layer, expressed in MPa.

[0025] The calculation process for the bottomhole flowing pressure difference between the lower and upper oil layers is as follows:

[0026]

[0027] In the formula: △p wf The bottomhole flowing pressure difference between the lower and upper oil layers, in MPa;

[0028] M1 is the fluid production index when the lower oil layer is producing alone, m 3 / d·MPa; N1 is the production pressure differential when the lower oil layer is producing alone, MPa; M2 is the fluid production index when the upper oil layer is producing alone, m 3 / d·MPa; N2 is the production pressure differential when the upper oil layer is produced alone, in MPa.

[0029] The specific process of correcting the bottom hole flowing pressure is as follows:

[0030] If △p wf >△p 损失 The production pressure differential when the oil layer is produced alone is corrected to the production pressure differential when the two layers are produced together.

[0031] N1′=p e1 -G1(r e1 -r w1 )-Δp wf +Δp 损失

[0032] In the formula: N1' is the production pressure difference of the lower oil layer when the two layers are produced together, in MPa;

[0033] p e1 G1 is the formation pressure of the lower oil layer, in MPa; G1 is the starting pressure gradient of the lower oil layer; r e1 r is the oil supply radius of the lower oil layer, in meters. w1 The radius of the wellbore in the lower oil layer is given in meters.

[0034] Bottom-hole flowing pressure of the lower oil layer during combined production

[0035] In the formula: p' wf1 The bottom-hole flowing pressure of the lower oil layer during combined production of two layers, in MPa;

[0036] N2′=p e2 -G2(r e2 -r w2 )-Δp 损失

[0037] In the formula: N2' is the production pressure difference of the upper oil layer when the two layers are produced together, in MPa;

[0038] p e2 G1 is the formation pressure of the upper oil layer, MPa; G2 is the starting pressure gradient of the upper oil layer; r e2r is the oil supply radius of the upper oil layer, in meters. w2 The wellbore radius of the upper oil layer is in meters.

[0039] Bottom-hole flowing pressure of the upper oil layer during combined production of two layers

[0040] In the formula: p' wf2 The bottom-hole flowing pressure of the upper oil layer during combined production of two layers, in MPa;

[0041] If △p wf <△p 损失 N2′=p e2 -G2(r e2 -r w2 )+Δp wf -2Δp 损失

[0042] Corrected bottomhole flowing pressure of upper oil layer

[0043] The specific process of obtaining the flow rate of each oil layer and the total flow rate by correcting the bottom hole flowing pressure is as follows:

[0044] If △p wf >△p 损失 ,

[0045]

[0046]

[0047] If △p wf <△p 损失 ,

[0048]

[0049]

[0050] Q 合 =Q 1+ Q2;

[0051] In the formula: Q1 is the bottom hole flow rate of the lower oil layer when two layers are produced simultaneously, in m³. 3 / d;

[0052] Q2 is the bottom-hole flow rate of the upper oil layer during combined production of two layers, in m³. 3 / d;

[0053] Q 合 For the total flow rate, m 3 / d.

[0054] The calculation process for the combined mining limit flow rate is as follows:

[0055] The minimum distance between oil layers is 8m;

[0056] Limits to the magnitude of traffic loss Joint procurement boundary flow Q 合min =(Q 1max +Q 2max (1-R) max );

[0057] In the formula: R max This represents the limit of the flow loss magnitude and is dimensionless.

[0058] Q 1max The flow rate (m) is the flow rate when the lower oil layer is producing independently. 3 / d;

[0059] Q 2max The flow rate (m) is the flow rate when the upper reservoir is producing independently. 3 / d;

[0060] D C The annual average decline rate during the combined mining of two layers is dimensionless.

[0061] D C1 The annual average decline rate of single-layer oil production in the lower oil layer is dimensionless.

[0062] D C2 The annual average decline rate of single-production oil recovery in the upper reservoir is dimensionless.

[0063] F represents the deposit interest rate, which is dimensionless.

[0064] T represents the production years at the time of joint mining, in years;

[0065] T1 represents the production life of the lower oil layer when it is produced alone, in years; T2 represents the production life of the upper oil layer when it is produced alone, in years.

[0066] The process for determining whether the lower and upper oil layers can be jointly mined is as follows:

[0067] The combined procurement boundary flow Q 合min Substituting these values ​​into the graph showing the relationship between total flow rate and vertical distance between combined mining layers under different flow coefficient ratios, we obtain the boundary values ​​for different vertical distances between combined mining layers and the flow coefficient ratio. These boundary values ​​revert to the boundary relationship curve between the flow coefficient ratio and the vertical distance between combined mining layers. When the values ​​of the vertical distance between the lower and upper oil layers and the flow coefficient ratio are above the boundary relationship curve between the flow coefficient ratio and the vertical distance between combined mining layers, the lower and upper oil layers can be combined for mining; otherwise, they cannot be combined for mining.

[0068] The technical effects of this invention are as follows:

[0069] The graphs showing the relationship between total flow rate and vertical distance between combined production layers under different flow coefficient ratios, as well as the boundary curves showing the relationship between flow coefficient ratio and vertical distance between combined production layers, generated by this invention, can quickly determine whether to use single or combined production for each oil layer in a multi-layered reservoir, providing a theoretical basis and guidance for block development models. Attached Figure Description

[0070] Figure 1 This is a schematic diagram illustrating the dynamic inflow of oil wells into a multi-layered oil reservoir using a water injection development layer recombination method according to the present invention.

[0071] Figure 2 This invention relates to a method for reorganizing the stratigraphic layers in the YGS block of the Yanchang Oilfield, specifically for water injection development of multi-layered reservoirs. H-relationship curve.

[0072] Figure 3 This invention relates to a method for reorganizing the stratigraphic layers in the YGS block of the Yanchang Oilfield, specifically for water injection development of multi-layered reservoirs. H-relationship curve.

[0073] Figure 4 This invention relates to a method for reorganizing the stratigraphic layers in the water injection development of multi-layered oil reservoirs, specifically for the Chang 2 and Chang 3 blocks of the YGS block in the Yanchang Oilfield. H-relationship curve.

[0074] Figure 5 This invention relates to a method for reorganizing the stratigraphic layers in the YGS block of the Yanchang Oilfield, specifically for water injection development of multi-layered reservoirs. Boundary relationship curve diagram.

[0075] Figure 6 This invention relates to a method for reorganizing the stratigraphic layers in the YGS block of the Yanchang Oilfield, specifically for water injection development of multi-layered reservoirs. Boundary relationship curve diagram.

[0076] Figure 7 This invention relates to a method for reorganizing the stratigraphic layers in the water injection development of multi-layered oil reservoirs, specifically for the Chang 2 and Chang 3 blocks of the YGS block in the Yanchang Oilfield. Boundary relationship curve diagram. Detailed Implementation

[0077] A method for reorganizing the strata in water injection development of multi-layered oil reservoirs, the method is as follows:

[0078] To obtain the bottomhole flowing pressure when the oil reservoir is producing independently;

[0079] Calculate the pressure loss of the fluid flowing from the lower oil layer to the upper oil layer;

[0080] The bottomhole flowing pressure difference and pressure loss between the lower and upper oil layers are compared, and the production pressure difference when the oil layer is producing alone is corrected to the production pressure difference when the two layers are produced together, thus obtaining the corrected bottomhole flowing pressure.

[0081] The flow rates of each oil layer and the total flow rate were obtained by correcting the bottom hole flowing pressure calculation.

[0082] Plot a graph showing the relationship between total flow rate and vertical distance of combined mining operations under different flow coefficient ratios;

[0083] The limit of flow loss is determined based on the minimum inter-oil layer distance and economic benefits, and the limit flow of combined production is obtained.

[0084] Based on the relationship chart between total flow rate and vertical distance between combined mining operations under different flow coefficient ratios, and the limit flow rate of combined mining operations, determine the relationship chart between flow coefficient ratio and vertical distance between combined mining operations, and determine whether the lower oil layer and the upper oil layer can be combined for mining.

[0085] The calculation process for obtaining the bottomhole flowing pressure when the oil reservoir is producing independently is as follows:

[0086]

[0087] In the formula: p wf ρ is the bottom hole flowing pressure, MPa; d is the wellbore diameter, m; ρ is the fluid density, 10 3 kg / m 3 M is the fluid collection index, m 3 / d·MPa; N is the production pressure difference, MPa;

[0088] in,

[0089]

[0090] Where: k is the effective permeability of the oil layer, mD; h is the effective thickness of the oil layer, m; μ is the fluid viscosity, mPa·s; B is the volume coefficient, dimensionless; r e R is the fuel supply radius, in meters (m); w p is the wellbore radius, in meters. e ρ is the formation pressure, MPa; G is the starting pressure gradient, MPa / m.

[0091] The calculation process for the pressure loss of the fluid flowing from the lower oil layer to the upper oil layer is as follows:

[0092]

[0093] Where: g is the acceleration due to gravity, N / kg; H is the vertical distance between the two mining operations, m;

[0094] △p 损失This represents the pressure loss of fluid flowing from the lower oil layer to the upper oil layer, expressed in MPa.

[0095] The calculation process for the bottomhole flowing pressure difference between the lower and upper oil layers is as follows:

[0096]

[0097] In the formula: △p wf The bottomhole flowing pressure difference between the lower and upper oil layers, in MPa;

[0098] M1 is the fluid production index when the lower oil layer is producing alone, m 3 / d·MPa; N1 is the production pressure differential when the lower oil layer is producing alone, MPa; M2 is the fluid production index when the upper oil layer is producing alone, m 3 / d·MPa; N2 is the production pressure differential when the upper oil layer is produced alone, in MPa.

[0099] The specific process of correcting the bottom hole flowing pressure is as follows:

[0100] If △p wf >△p 损失 The production pressure differential when the oil layer is produced alone is corrected to the production pressure differential when the two layers are produced together.

[0101] N1′=p e1 -G1(r e1 -r w1 )-Δp wf +Δp 损失

[0102] In the formula: N1' is the production pressure difference of the lower oil layer when the two layers are produced together, in MPa;

[0103] p e1 G1 is the formation pressure of the lower oil layer, in MPa; G1 is the starting pressure gradient of the lower oil layer; r e1 r is the oil supply radius of the lower oil layer, in meters. w1 The radius of the wellbore in the lower oil layer is given in meters.

[0104] Bottom-hole flowing pressure of the lower oil layer during combined production

[0105] In the formula: p' wf1 The bottom-hole flowing pressure of the lower oil layer during combined production of two layers, in MPa;

[0106] N2′=p e2 -G2(r e2 -r w2 )-Δp 损失

[0107] In the formula: N2' is the production pressure difference of the upper oil layer when the two layers are produced together, in MPa;

[0108] p e2 G1 is the formation pressure of the upper oil layer, MPa; G2 is the starting pressure gradient of the upper oil layer; r e2 r is the oil supply radius of the upper oil layer, in meters. w2 The wellbore radius of the upper oil layer is in meters.

[0109] Bottom-hole flowing pressure of the upper oil layer during combined production of two layers

[0110] In the formula: p' wf2 The bottom-hole flowing pressure of the upper oil layer during combined production of two layers, in MPa;

[0111] If △p wf <△p 损失 N2′=p e2 -G2(r e2 -r w2 )+Δp wf -2Δp 损失

[0112] Corrected bottomhole flowing pressure of upper oil layer

[0113] The specific process of obtaining the flow rate of each oil layer and the total flow rate by correcting the bottom hole flowing pressure is as follows:

[0114] If △p wf >△p 损失 ,

[0115]

[0116]

[0117] If △p wf <△p 损失 ,

[0118]

[0119]

[0120] Q 合 =Q 1+ Q2;

[0121] In the formula: Q1 is the bottom hole flow rate of the lower oil layer when two layers are produced simultaneously, in m³. 3 / d;

[0122] Q2 is the bottom-hole flow rate of the upper oil layer during combined production of two layers, in m³. 3 / d;

[0123] Q 合 For the total flow rate, m 3 / d.

[0124] The calculation process for the combined mining limit flow rate is as follows:

[0125] The minimum distance between oil layers is 8m;

[0126] Limits to the magnitude of traffic loss Joint procurement boundary flow Q 合min =(Q 1max +Q 2max (1-R) max );

[0127] In the formula: R max This represents the limit of the flow loss magnitude and is dimensionless.

[0128] Q 1max The flow rate (m) is the flow rate when the lower oil layer is producing independently. 3 / d;

[0129] Q 2max The flow rate (m) is the flow rate when the upper reservoir is producing independently. 3 / d;

[0130] D C The annual average decline rate during the combined mining of two layers is dimensionless.

[0131] D C1 The annual average decline rate of single-layer oil production in the lower oil layer is dimensionless.

[0132] D C2 The annual average decline rate of single-production oil recovery in the upper reservoir is dimensionless.

[0133] F represents the deposit interest rate, which is dimensionless.

[0134] T represents the production years at the time of joint mining, in years;

[0135] T1 represents the production life of the lower oil layer when it is produced alone, in years; T2 represents the production life of the upper oil layer when it is produced alone, in years.

[0136] The process for determining whether the lower and upper oil layers can be jointly mined is as follows:

[0137] The combined procurement boundary flow Q 合minSubstituting these values ​​into the graph showing the relationship between total flow rate and vertical distance between combined mining layers under different flow coefficient ratios, we obtain the boundary values ​​for different vertical distances between combined mining layers and the flow coefficient ratio. These boundary values ​​revert to the boundary relationship curve between the flow coefficient ratio and the vertical distance between combined mining layers. When the values ​​of the vertical distance between the lower and upper oil layers and the flow coefficient ratio are above the boundary relationship curve between the flow coefficient ratio and the vertical distance between combined mining layers, the lower and upper oil layers can be combined for mining; otherwise, they cannot be combined for mining.

[0138] Specific experimental example (This example takes the Yanchang 1, Yanchang 2, and Yanchang 4+5 reservoirs in the YGS well area of ​​the Yanchang Oilfield as examples, with Yanchang 2 and Yanchang 4+5 as the lower oil layers)

[0139] A method for reorganizing the strata in water injection development of multi-layered oil reservoirs, the method is as follows:

[0140] Step 1: Obtaining basic reservoir parameters;

[0141] Statistics on formation pressure P in different reservoirs e The starting pressure gradient G was measured in the laboratory; the effective thickness h of the oil layer was obtained through secondary interpretation of the oil layer; the effective permeability k of the oil layer was obtained through well logging analysis; the fluid density ρ was obtained through the specific gravity method; the fluid viscosity μ was obtained through Newton's Nemoza law; the volume factor B; and the oil supply radius r. e Wellbore radius r w ;

[0142] Obtain the bottomhole flowing pressure when the oil reservoir is producing independently; see Table 1 for details.

[0143] Table 1 Basic Reservoir Parameters

[0144] <![CDATA[Formation pressure P of length 1 / length 2 / length 4 + 5 e (MPa)]]> 16.49 / 16.83 / 18 <![CDATA[Length 1 / Length 2 / Length 4 + 5 Fluid density ρ (10 3 kg / m 3 )]]> 0.831 / 0.832 / 0.854 Initiation pressure gradient G (MPa / m) for reservoirs 1 / 2 / 4+5 0.035 / 0.04 / 0.05 Effective thickness h (m) of oil layer in length 1 / length 2 / length 4+5 5.5 / 5.10 / 3.92 Effective permeability k(mD) of oil layers in length 1 / length 2 / length 4+5 15.8 / 15.7 / 0.76 Oil layer fluid viscosity μ (mPa·s) for length 1 / length 2 / length 4+5 8.35 / 8.81 / 2.33 Volume coefficient B for length 1 / length 2 / length 4+5 1.183 / 1.190 / 1.215 <![CDATA[Length 1 / Length 2 / Length 4+5 Fuel supply radius r e (m)]]> 132 / 132 / 150 <![CDATA[Length 1 / Length 2 / Length 4 + 5 Wellbore radius r w (m)]]> 0.2 / 0.2 / 0.2

[0145] Step 2: Calculate the pressure loss of fluid flowing from the lower oil layer to the upper oil layer;

[0146] pass

[0147]

[0148] The bottom hole flowing pressure, flow rate, combined production vertical distance and flow coefficient ratio of each oil layer when each oil layer (Chang 1 and Chang 2, Chang 1 and Chang 4+5, Chang 2 and Chang 4+5) exists simultaneously were calculated.

[0149] Table 2 shows the bottom hole flowing pressures when each reservoir is producing independently.

[0150] Table 2 Bottomhole flowing pressure during individual oil production of each layer

[0151] Layer Length 1 Length 2 4+5 Bottom hole flowing pressure (MPa) 9.45 8.82 5.86 <![CDATA[Flow rate (m 3 / d)]]> 18.20 17.58 14.33

[0152] Table 3 shows the bottom hole flowing pressures when all oil-bearing layers exist simultaneously and the lower reservoir is the Chang 2 oil layer producing alone.

[0153] Table 3 Bottomhole flowing pressure when all oil layers exist simultaneously and the lower reservoir is the Chang 2 oil layer producing alone.

[0154]

[0155]

[0156]

[0157] Table 4 shows the bottom hole flowing pressures when all oil-bearing layers exist simultaneously and the lower oil reservoir is the Chang 4+5 oil layer producing alone.

[0158] Table 4 shows the bottom hole flowing pressures when all oil layers exist simultaneously and the lower reservoir is the Chang 4+5 reservoir producing alone.

[0159]

[0160]

[0161] according to

[0162]

[0163] The pressure loss of the fluid flowing from the lower oil layer to the upper oil layer was calculated, as shown in Table 5;

[0164] Table 5. Pressure loss at different distances and with different flow coefficients in a combined oil reservoir, flowing from the lower oil layer to the upper oil layer.

[0165]

[0166]

[0167] Step 3: Through

[0168]

[0169] The bottomhole flowing pressure difference between the lower and upper oil layers was calculated.

[0170] Step 4: Compare the bottomhole flowing pressure difference between the lower and upper oil layers with the pressure loss of fluid flowing from the lower oil layer to the upper oil layer.

[0171] If △p wf >△p 损失 The production pressure differential when the oil layer is produced alone is corrected to the production pressure differential when the two layers are produced together.

[0172] N1′=p e1 -G1(re1 -r w1 )-Δp wf +Δp 损失

[0173] Bottom-hole flowing pressure of the lower oil layer during combined production

[0174] N2′=p e2 -G2(r e2 -r w2 )-×p 损失

[0175] Bottom-hole flowing pressure of the upper oil layer during combined production of two layers

[0176] If △p wf <△p 损失 N2′=p e2 -G2(r e2 -r w2 )+Δp wf -2Δp 损失

[0177] Corrected bottomhole flowing pressure of upper oil layer

[0178] Step 5: Obtain the flow rate of each oil layer and the total flow rate by correcting the bottom hole flowing pressure calculation;

[0179] If △p wf >△p 损失 ,

[0180]

[0181]

[0182] If △p wf <△p 损失 ,

[0183]

[0184]

[0185] Through Q 合 =Q 1+ Q2; Calculate the total flow rate (as shown in Tables 6 to 8).

[0186] Table 6 Total flow rate when Chang 1 and Chang 2 are used together

[0187]

[0188]

[0189] Table 7 Total flow rate during combined mining of Chang 1 and Chang 4+5

[0190]

[0191]

[0192] Table 8 Total flow rate during the combined mining of Chang 2 and Chang 4+5

[0193]

[0194]

[0195]

[0196] Step 6: Plot the relationship between total flow rate and vertical distance of combined sampling at different flow coefficient ratios; see Figures 2-4 .

[0197] Step 7: Determine the flow loss range limit based on the minimum oil layer distance of 8m and economic benefits, and obtain the combined production flow limit of each oil layer, as shown in Table 9.

[0198] Table 9. Limits to Flow Loss During Combined Production of Two Oil Layers

[0199] Composite layer system <![CDATA[R max ]]> Joint Procurement Flow Limits Length 1 and Length 2 22％ 27.90 Length 1 and Length 4+5 21％ 25.84 Length 2 and Length 4+5 21％ 25.33

[0200] Step 8: Set the joint procurement flow limit Q 合min Substituting the values ​​into the graph showing the relationship between total flow rate and vertical distance of combined mining under different flow coefficient ratios, we obtain the limit values ​​of vertical distance of combined mining and flow coefficient ratio for different ratios (see Tables 10-12).

[0201] Table 10: Limits on Vertical Distance and Flow Coefficient for Combined Mining Operations of Chang 1 and Chang 2

[0202] Vertical distance between mining operations (m) Flow coefficient ratio 0 0.37 255 0.4 430 0.5 550 0.6 639 0.7 705 0.8 761 0.9 804 1

[0203] Table 11. Limits on Vertical Distance and Flow Coefficient for Combined Mine Lines 1 and 4+5

[0204]

[0205]

[0206] Table 12: Limits on Vertical Distance and Flow Coefficient for Combined Mine Operations of Chang 2 and Chang 4+5

[0207] Vertical distance between mining operations (m) Flow coefficient ratio 0 0.41 133 0.5 237 0.6 323 0.7 382 0.8 436 0.9 478 1

[0208] The boundary values ​​of different combined vertical distances and flow coefficient ratios are regressed to form a boundary relationship curve between the flow coefficient ratio and the combined vertical distance, and the flow coefficient ratio is plotted. A graph showing the boundary relationship between the vertical distance to the joint mining operation (as attached). Figure 5 ~Attached Figure 7 ).

[0209] If the values ​​of the combined vertical distance and flow coefficient ratio of the lower and upper oil layers are above the boundary curve between the flow coefficient ratio and the combined vertical distance, the lower and upper oil layers can be combined for production; otherwise, they cannot be combined for production.

[0210] When Long 1 and Long 2 are mined together, the flow coefficient is higher than that of Long 2. The vertical distance H between the two mining operations satisfies the following relationship: It is advisable to combine them at the same time;

[0211] When Long 1 and Long 4+5 are combined, the flow coefficient is higher than that of Long 4+5. The vertical distance H between the two mining operations satisfies the following relationship: Joint procurement is possible;

[0212] When Long 2 and Long 4+5 are combined, the flow coefficient is compared to The vertical distance H between the two mining operations satisfies the following relationship: Joint procurement is possible.

[0213] Typical oil well application analysis:

[0214] Y1 oil well: The Chang 1 and Chang 2 reservoirs are developed. The Chang 1 oil layer has a depth of 1945m and an effective permeability of 15.6×10⁻⁶. -3 μm 2 The effective thickness of the oil layer is 6m, and the fluid viscosity is 8.5mPa·s; the depth of the oil layer in section 2 is 1985m, and the effective permeability of the oil layer is 15.5×10⁻⁶. -3 μm 2 The effective thickness of the oil layer is 5.5 m, and the fluid viscosity is 8.9 mPa·s; the flow coefficient ratio is... H is 40m. Joint procurement is possible.

[0215] Y2 oil well: The Chang 1 and Chang 4+5 reservoirs are developed. The Chang 1 oil layer has a depth of 1952m and an effective permeability of 15.5×10⁻⁶ m. -3 μm 2 The effective thickness of the oil layer is 5.8 m, and the fluid viscosity is 8.2 mPa·s; the depth of the 4+5 oil layer is 2256 m, and the effective permeability of the oil layer is 0.9 × 10⁻⁶. -3 μm 2 The effective thickness of the oil layer is 4m, and the fluid viscosity is 2.2mPa·s; the flow coefficient is higher than that of the oil layer. H is 304m. Joint purchases are not allowed.

[0216] Y3 oil well: The Chang 2 and Chang 4+5 reservoirs are developed. The Chang 2 oil layer has a depth of 2000m and an effective permeability of 15.2×10⁻⁶. -3 μm 2 The effective thickness of the oil layer is 5.2m, and the fluid viscosity is 8.4mPa·s; the depth of the 4+5 oil layer is 2263m, and the effective permeability of the oil layer is 0.86×10⁻⁵. -3 μm 2 The effective thickness of the oil layer is 3.8 m, and the fluid viscosity is 2.1 mPa·s; the flow coefficient ratio is... H is 263m. Joint purchases are not allowed.

Claims

1. A method for reorganizing the stratigraphic layers during water injection development in a multi-layered oil reservoir, characterized in that: The method is as follows: To obtain the bottomhole flowing pressure when the oil reservoir is producing independently; Calculate the pressure loss of the fluid flowing from the lower oil layer to the upper oil layer; The bottomhole flowing pressure difference and pressure loss between the lower and upper oil layers are compared, and the production pressure difference when the oil layer is producing alone is corrected to the production pressure difference when the two layers are produced together, thus obtaining the corrected bottomhole flowing pressure. The flow rates of each oil layer and the total flow rate were obtained by correcting the bottom hole flowing pressure calculation. Plot a graph showing the relationship between total flow rate and vertical distance of combined mining operations under different flow coefficient ratios; The limit of flow loss is determined based on the minimum inter-oil layer distance and economic benefits, and the limit flow of combined production is obtained. Based on the relationship chart between total flow rate and vertical distance between combined mining operations under different flow coefficient ratios, and the limit flow rate of combined mining operations, determine the relationship chart between flow coefficient ratio and vertical distance between combined mining operations, and determine whether the lower oil layer and the upper oil layer can be combined for mining.

2. The method for reorganizing the formation of multi-layered reservoirs through water injection development according to claim 1, characterized in that: The calculation process for obtaining the bottom hole flowing pressure when the oil reservoir is producing independently is as follows: In the formula: p wf ρ is the bottom hole flowing pressure, MPa; d is the wellbore diameter, m; ρ is the fluid density, 10 3 kg / m 3 M is the fluid collection index, m 3 / d·MPa; N is the production pressure difference, MPa; in, Where: k is the effective permeability of the oil layer, mD; h is the effective thickness of the oil layer, m; μ is the fluid viscosity, mPa·s; B is the volume coefficient, dimensionless; r e R is the fuel supply radius, in meters (m); w p is the wellbore radius, in meters. e ρ is the formation pressure, MPa; G is the starting pressure gradient, MPa / m.

3. The method for reorganizing the formation of multi-layered reservoirs through water injection development according to claim 2, characterized in that: The calculation process for the pressure loss of the fluid flowing from the lower oil layer to the upper oil layer is as follows: Where: g is the acceleration due to gravity, N / kg; H is the vertical distance between the two mining operations, m; △p 损失 Pressure loss for fluid flow from lower reservoir location to upper reservoir location, MPa.

4. The method for reorganizing the formation of multi-layered reservoirs through water injection development according to claim 1, characterized in that: The calculation process for the bottomhole flowing pressure difference between the lower and upper oil layers is as follows: wherein: Δp wf is the bottom hole flowing pressure differential between the lower and upper oil zones, MPa; M1 is the fluid production index when the lower oil layer is producing alone, m 3 / d·MPa; N1 is the production pressure differential when the lower oil layer is producing alone, MPa; M2 is the fluid production index when the upper oil layer is producing alone, m 3 / d·MPa; N2 is the production pressure differential when the upper oil layer is produced alone, in MPa.

5. The method for reorganizing the formation of multi-layered reservoirs through water injection development according to claim 4, characterized in that: The specific process for correcting the bottom hole flowing pressure is as follows: If △p wf >△p 损失 The production pressure differential when the oil layer is produced alone is corrected to the production pressure differential when the two layers are produced together. N′1=p e1 -G1(r e1 -r w1 )-Δp wf +Δp 损失 In the formula: N1' is the production pressure difference of the lower oil layer when the two layers are produced together, in MPa; p e1 G1 is the formation pressure of the lower oil layer, in MPa; G1 is the starting pressure gradient of the lower oil layer; r e1 r is the oil supply radius of the lower oil layer, in meters. w1 The radius of the wellbore in the lower oil layer is given in meters. Bottom-hole flowing pressure of the lower oil layer during combined production In the formula: p' wf1 The bottom-hole flowing pressure of the lower oil layer during combined production of two layers, in MPa; N'2= p e2 - G2(r e2 - r w2 ) - Δp 损失 In the formula: N2' is the production pressure difference of the upper oil layer when the two layers are produced together, in MPa; p e2 G1 is the formation pressure of the upper oil layer, MPa; G2 is the starting pressure gradient of the upper oil layer; r e2 r is the oil supply radius of the upper oil layer, in meters. w2 The wellbore radius of the upper oil layer is in meters. Bottom-hole flowing pressure of the upper oil layer during combined production of two layers In the formula: p' wf2 The bottom-hole flowing pressure of the upper oil layer during combined production of two layers, in MPa; If △p wf <△p 损失 N2′=p e2 -G2(r e2 -r w2 )+Δp wf -2Δp 损失 Corrected bottomhole flowing pressure of upper oil layer 6. The method for reorganizing the formation of multi-layered reservoirs through water injection development according to claim 5, characterized in that: The specific process of obtaining the flow rate of each oil layer and the total flow rate by correcting the bottom hole flowing pressure calculation is as follows: if Δp wf > Δp 损失 , If Δp wf < Δp 损失 , Q 合 =Q 1+ Q2; In the formula: Q1 is the bottom hole flow rate of the lower oil layer when two layers are produced simultaneously, in m³. 3 / d; Q2 is the bottom-hole flow rate of the upper oil layer during combined production of two layers, in m³. 3 / d; Q 合 For the total flow rate, m 3 / d.

7. The method for reorganizing the formation of multi-layered reservoirs through water injection development according to claim 6, characterized in that: The calculation process for the combined mining limit flow rate is as follows: The minimum distance between oil layers is 8m; Limits to the magnitude of traffic loss Joint procurement boundary flow Q 合min =(Q 1max +Q 2max (1-R) max ); In the formula: R max This represents the limit of the flow loss magnitude and is dimensionless. Q 1max The flow rate (m) is the flow rate when the lower oil layer is producing independently. 3 / d; Q 2max The flow rate (m) is the flow rate when the upper reservoir is producing independently. 3 / d; D C The annual average decline rate during the combined mining of two layers is dimensionless. D C1 The annual average decline rate of single-layer oil production in the lower oil layer is dimensionless. D C2 The annual average decline rate of single-production oil recovery in the upper reservoir is dimensionless. F represents the deposit interest rate, which is dimensionless. T represents the production years at the time of joint mining, in years; T1 represents the production life of the lower oil layer when it is produced alone, in years; T2 represents the production life of the upper oil layer when it is produced alone, in years.

8. The method for reorganizing the formation of multi-layered reservoirs through water injection development according to claim 7, characterized in that: The process for determining whether the lower and upper oil layers can be co-produced is as follows: The co-produced boundary flow rate Q is... 合min Substituting these values ​​into the graph showing the relationship between total flow rate and vertical distance between combined mining layers under different flow coefficient ratios, we obtain the boundary values ​​for different vertical distances between combined mining layers and the flow coefficient ratio. These boundary values ​​revert to the boundary relationship curve between the flow coefficient ratio and the vertical distance between combined mining layers. When the values ​​of the vertical distance between the lower and upper oil layers and the flow coefficient ratio are above the boundary relationship curve between the flow coefficient ratio and the vertical distance between combined mining layers, the lower and upper oil layers can be combined for mining; otherwise, they cannot be combined for mining.

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