A method for analyzing dynamic and static connectivity of sand bodies in oil and water wells

Abstract

The invention relates to a method for analyzing the dynamic and static connectivity of oil and water well sand bodies, and the method comprises the following steps: determining static connectivity; obtaining the static connectivity of the sand bodies by multiplying the sand-to-land ratio S, the connectivity of the sand body distribution, and the connectivity of the vertical overlap; determining dynamic connectivity; clarifying the perforation perfection, water drive reserve control, and injection-production correspondence of each oil production well; using the effective thickness, porosity, permeability, static connectivity of the sand bodies, the perforation perfection, the water drive reserve control, and the injection-production correspondence obtained above as evaluation parameters, normalizing and weighting the evaluation parameters, and using the sum of the products of the normalized evaluation parameters and their corresponding weights as static and dynamic connectivity coefficients; and evaluating inter-well connectivity by using the static and dynamic connectivity coefficients. The method combines the dynamic and static connectivity relationships, enables the two to be mutually verified, and has high operability, is conducive to improving the rationality of determining the connectivity between injection and production wells in low-permeability oil reservoirs, and facilitates in-depth research and formulation of refined water injection policies.

Description

Technical Field

[0001] The invention relates to the technical field of improving oil field recovery rate, and in particular to a method for analyzing dynamic and static connectivity conditions of oil-water well sand bodies. Background Art

[0002] Currently, industry research on sand connectivity between oil and water wells primarily utilizes tracer methods, statistical analysis of injection-production data, oil well production fluctuation tests based on water well fluctuations, and the magnitude of oil well fluid production fluctuations. Sand connectivity analysis typically uses parameters such as connectivity thickness and perforation thickness ratio to determine connectivity. Conventional methods for analyzing injection-production system connectivity alone are no longer sufficient to meet the needs of oilfield development. Dynamic and static sand connectivity analysis methods combine static research findings with dynamic production data to more comprehensively analyze the connectivity of production sections in oil and water wells, improving the adaptability of injection-production systems.

[0003] The existing method, "A Method for Evaluating Static Connectivity of Interwell Sand Bodies Based on Sedimentary Environment and Evaluation Scale," evaluates the probability of static connectivity of conductive layers based on formation sand-to-ground ratios, sedimentary environment, and other sandstone parameters, thereby quantitatively evaluating the static connectivity of sand bodies of different genetic types. This method focuses on the sedimentary environment and employs a factor control method to clarify the controlling factors of static connectivity of conductive layers. It then quantitatively evaluates the connectivity of sandstone conductive layers through forward modeling of sandbody connectivity. This method utilizes a sequential Gaussian algorithm and modeling software, Petrel, to achieve quantitative output and prioritize favorable oil and gas distribution zones. Currently, the calculation of static connectivity of sand bodies is influenced by numerous uncertainties, such as provenance direction and well spacing. Conventional evaluation methods require extensive computational effort. Quantitative evaluation of uncertainty parameters affecting sandbody connectivity is computationally inefficient and presents significant development risks.

[0004] The prior art "A Method for Determining the Dynamic Connectivity of Oil and Water Wells" states that most domestic oilfields use waterflooding to replenish reservoir pressure. The degree of waterflooding significantly impacts the production of production wells and reflects the dynamic connectivity between the injection and production wells. To determine the dynamic connectivity between injection and production wells, methods such as interwell tracers, pressure testing, well test analysis, or model inversion are primarily used. Dynamic quantitative analysis primarily determines interwell connectivity based on the changing patterns of injection and production data. This method is used to implement appropriate measures to address underinjection. The results of the dynamic connectivity analysis of oil and water wells are relatively accurate and provide valuable guidance for actual production. However, evaluating the adaptability of injection and production systems solely based on the degree of waterflooding control is no longer sufficient to meet the needs of oilfield development. Conventional methods such as interwell tracers, pressure testing, or well test analysis require targeted, time-consuming, and disruptive operations, as well as high costs. Summary of the Invention

[0005] The present invention aims to address the above problems and proposes a method for analyzing the dynamic and static connectivity of oil and water well sand bodies, which comprehensively analyzes the dynamic and static connectivity of oil and water well sand bodies and solves the problems of low injection-production correspondence rate, prominent interlayer contradictions, and unobvious water injection effect in oil reservoir development.

[0006] The technical solution of the present invention is:

[0007] A method for analyzing the dynamic and static connectivity of sand bodies in oil and water wells is as follows:

[0008] (1) Conducting static connectivity assessment;

[0009] Step 1-1: Determine the formation thickness H, effective sand body thickness h, porosity φ and permeability K of each production well with the water injection well as the center of the production and injection well group;

[0010] Step 1-2: Divide the effective thickness of the sand body h by the formation thickness H to obtain the sand-to-formation ratio S;

[0011] Step 1-3: Through interlayer characterization, the sand body distribution characteristics and vertical overlap relationship between the single sand bodies in the injection and production well group are obtained; according to the specific situation of the sand body distribution, the degree of connectivity of the sand body distribution I is obtained. h , according to the specific situation of longitudinal overlap, the degree of longitudinal overlap connectivity I is obtained z ;

[0012] Step 1-4: Sand-to-ground ratio S, sand distribution connectivity degree I h and the degree of vertical overlapping connectivity I z The product of the static connectivity degree of the sand body I is obtained 静 ;

[0013] (2) Conduct dynamic connectivity assessment;

[0014] Clarify the perforation perfection P and water drive reserve control degree Z of each oil well k and the injection-production correspondence degree λ;

[0015] (3) The effective thickness h, porosity φ, permeability K, and static connectivity I of the sand body obtained above are 静 , perforation perfection P, water drive reserve control degree Z k The above evaluation parameters are normalized and weighted, and the sum of the products of the normalized evaluation parameters and their corresponding weights is used as the static and dynamic connectivity coefficient K. 连 ;

[0016] If the static and dynamic connectivity coefficient K 连 >0.76, indicating good inter-well connectivity;

[0017] If the static and dynamic connectivity coefficient K 连between 0.57 and 0.76, indicating moderate interwell connectivity;

[0018] If the static and dynamic connectivity coefficient K 连 <0.57, indicating poor inter-well connectivity.

[0019] in,

[0020] The static and dynamic connectivity coefficient K 连 The specific calculation formula is:

[0021] Static and dynamic connectivity coefficient K 连 =A1×h+B1×φ+C1×K+D1×I 静 +Z k1 ×P+F1×Z k +G1×λ;

[0022] Among them, A1 is the weight value of the effective thickness h of the sand body; B1 is the weight value of the porosity φ; C1 is the weight value of the permeability K; D1 is the static connectivity degree I of the sand body 静 The weight value of Z k1 is the weight value of the perforation perfection degree P; F1 is the water drive reserve control degree Z k The weight value of G1 is the weight value of the injection-production degree λ;

[0023] The static and dynamic connectivity coefficient K 连 The specific calculation formula is:

[0024] Static and dynamic connectivity coefficient K 连 =0.11h+0.04φ+0.04K+0.16I 静 +0.27P+0.22Z k +0.16λ.

[0025] in,

[0026] The steps 1-3 obtain the longitudinal overlapping connectivity degree I z The specific process is:

[0027] Among them, the sand body distribution characteristics are divided into lateral separation type, lateral butt joint type, lateral cut-over type and lateral replacement type according to the lateral contact mode;

[0028] Among them, the lateral separation type is not connected; the lateral substitution type has poor connectivity;

[0029] The lateral docking type includes underwater distributary channel underwater distributary channel and estuary bar-underwater distributary channel, both of which have medium connectivity;

[0030] The lateral cut-overlapping type includes estuary bar-underwater diversion channel, underwater diversion channel-underwater diversion channel, underwater natural levee-underwater diversion channel, and inter-diversion bay channel-underwater diversion channel; the estuary bar-underwater diversion channel has good connectivity, the underwater diversion channel-underwater diversion channel has good connectivity, the underwater natural levee-underwater diversion channel has poor connectivity, and the inter-diversion bay channel-underwater diversion channel has no connectivity; see Table 1;

[0031] Table 1 Classification of sand body lateral contact patterns and sand body lateral connectivity

[0032]

[0033] The vertical overlapping relationships include vertical separation, vertical superposition, vertical tangent and vertical substitution. The vertical separation has poor or even no connectivity, the vertical superposition has medium connectivity, the vertical tangent has good connectivity, and the vertical substitution has good connectivity (see Table 2).

[0034] Table 2 Vertical superposition relationship pattern of sand bodies and classification of vertical connectivity of sand bodies

[0035]

[0036] Good connectivity is assigned a value of 1, medium connectivity is assigned a value of 0.79, and poor connectivity is assigned a value of 0.5.

[0037] in,

[0038] The static connectivity degree of the sand body is obtained in steps 1-4. 静 The specific process is:

[0039] Sand body static connectivity degree I 静 =S×I h ×Degree of vertical overlapping connectivity I z .

[0040] in,

[0041] Perforation perfection degree P, water drive reserve control degree Z k The specific solution process of the injection-production correspondence degree λ is as follows:

[0042] Perforation perfection degree P = perforated oil layer thickness / static connected thickness of oil layer;

[0043] Water drive reserve control degree Z k = Oil well perforation connected thickness / total oil layer thickness of oil well × 100%;

[0044] Injection-production correspondence degree λ = effective thickness of the oil well production layer connected to the water injection well / total effective thickness of the oil well production × 100%.

[0045] The technical effects of the present invention are:

[0046] The present invention combines the dynamic and static connectivity relationships to verify each other, has high operability, is conducive to improving the rationality of judging the connectivity status between injection and production wells in low permeability oil reservoirs, and facilitates in-depth research and formulation of refined water injection policies. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 Schematic diagram of the lateral contact pattern of the sand body of the present invention.

[0048] Figure 2 This is a schematic diagram of the longitudinal stacking relationship of the sand bodies of the present invention.

[0049] Figure 3 Schematic diagram of the method for analyzing the dynamic and static connectivity of sand bodies in oil and water wells according to the present invention.

[0050] Figure 4 This is a stratigraphic comparison diagram of the P26-1 water injection well group.

[0051] Figure 5 Schematic diagram of the vertical and lateral superposition relationship between the P26-1 water injection well and the oil well. DETAILED DESCRIPTION

[0052] A method for analyzing the dynamic and static connectivity of sand bodies in oil and water wells is as follows:

[0053] (1) Conducting static connectivity assessment;

[0054] Step 1-1: Determine the formation thickness H, effective sand body thickness h, porosity φ and permeability K of each production well with the water injection well as the center of the production and injection well group;

[0055] Step 1-2: Divide the effective thickness of the sand body h by the formation thickness H to obtain the sand-to-formation ratio S;

[0056] Step 1-3: Through interlayer characterization, the sand body distribution characteristics and vertical overlap relationship between the single sand bodies in the injection and production well group are obtained; according to the specific situation of the sand body distribution, the degree of connectivity of the sand body distribution I is obtained. h , according to the specific situation of longitudinal overlap, the degree of longitudinal overlap connectivity I is obtained z ;

[0057] The specific process is:

[0058] The sand body distribution characteristics are divided into lateral separation type, lateral butt joint type, lateral cut-overlap type and lateral replacement type according to the lateral contact mode; among them, the lateral separation type is not connected; the lateral replacement type has poor connectivity;

[0059] The lateral docking type includes underwater distributary channel underwater distributary channel and estuary bar-underwater distributary channel, both of which have medium connectivity;

[0060] The lateral cut-overlapping type includes estuary bar-underwater diversion channel, underwater diversion channel-underwater diversion channel, underwater natural levee-underwater diversion channel and inter-diversion bay channel-underwater diversion channel; the estuary bar-underwater diversion channel has good connectivity, the underwater diversion channel-underwater diversion channel has good connectivity, the underwater natural levee-underwater diversion channel has poor connectivity, and the inter-diversion bay channel-underwater diversion channel has no connectivity;

[0061] Among them, the vertical overlapping relationship includes vertical separation, vertical superposition, vertical cut-overlap and vertical substitution. Among them, the vertical separation type has poor connectivity or even no connectivity, the vertical superposition type has medium connectivity, the vertical cut-overlap type has good connectivity, and the vertical substitution type has good connectivity.

[0062] Good connectivity is assigned a value of 1, medium connectivity is assigned a value of 0.79, and poor connectivity is assigned a value of 0.5;

[0063] Step 1-4: Sand-to-ground ratio S, sand distribution connectivity degree I h and the degree of vertical overlapping connectivity I z The product of the static connectivity degree of the sand body I is obtained 静 ;

[0064] That is: the static connectivity degree of sand body I 静 =S×I h ×I z ;

[0065] (2) Conduct dynamic connectivity assessment;

[0066] Clarify the perforation perfection P and water drive reserve control degree Z of each oil well k and the injection-production correspondence degree λ;

[0067] Wherein, perforation perfection degree P = perforated oil layer thickness / static connected thickness of oil layer;

[0068] Water drive reserve control degree Z k = Oil well perforation connected thickness / total oil layer thickness of oil well × 100%;

[0069] Injection-production correspondence degree λ = effective thickness of the oil well production layer connected to the water injection well / total effective thickness of the oil well production × 100%;

[0070] (3) The effective thickness h, porosity φ, permeability K, and static connectivity I of the sand body obtained above are 静 , perforation perfection P, water drive reserve control degree Z k The above evaluation parameters are normalized and weighted, and the sum of the products of the normalized evaluation parameters and their corresponding weights is used as the static and dynamic connectivity coefficient K. 连 ;

[0071] That is: static and dynamic connectivity coefficient K 连 =0.11h+0.04φ+0.04K+0.16I 静 +0.27P+0.22Z k +0.16λ;

[0072] If the static and dynamic connectivity coefficient K 连 >0.76, indicating good inter-well connectivity;

[0073] If the static and dynamic connectivity coefficient K 连 between 0.57 and 0.76, indicating moderate interwell connectivity;

[0074] If the static and dynamic connectivity coefficient K 连 <0.57, indicating poor inter-well connectivity.

[0075] Specific experimental example - taking the C612-1 layer of the Ping 26-1 water injection well group as an example

[0076] A method for analyzing the dynamic and static connectivity of sand bodies in oil and water wells is as follows:

[0077] (1) Conducting static connectivity assessment;

[0078] Step 1-1: Based on the well logging data, calculate the formation thickness H, effective sand body thickness h, porosity φ and permeability K of each oil production well with the water injection well as the center of the injection and production well group;

[0079] Step 1-2: Divide the effective thickness of the sand body h by the formation thickness H to obtain the sand-to-formation ratio S; see Table 3 for relevant data;

[0080] Table 3 Static data statistics of oil and water wells in the C612-1 small layer of the P26-1 water injection well group

[0081]

[0082] Step 1-3: Through interlayer characterization, well area C612-1 can be further subdivided into two single sand bodies (C612-1-1 and C612-1-2). The two single sand bodies have both vertical superposition and lateral contact relationships; see Figure 5 According to the characteristics of the single sand body curve of each well, the vertical superposition relationship of the sand bodies of each well is identified, and the lateral contact relationship with the water injection well is judged. The specific relationship is shown in Table 4.

[0083] Table 4 Statistics of lateral contact relationship and vertical superposition relationship of sand bodies in C612-1 layer of P26-1 water injection well group

[0084] hashtag Lateral contact pattern between sand body and injection well Vertical superposition relationship model of sand bodies P26-1 (water injection well) Vertical cut stacking 1 P26-2 Side docking type 0.79 Vertical cut stacking 1 P26-3 Side cut stack 1 Vertical separation 0.5 P26-4 Side cut stack 1 Vertical separation 0.5 P26-5 Side cut stack 1 Vertical substitution 1 P26-6 Side cut stack 1 Vertical stacking type 1 P27-11 Side docking type 0.79 Vertical substitution 1

[0085] Step 1-4: Sand-to-ground ratio S, sand distribution connectivity degree I hand the degree of vertical overlapping connectivity I z The product of the static connectivity degree of the sand body I is obtained 静 ;See Table 5 for details;

[0086] Table 5 Static connectivity value assignment table for oil and water well sand bodies in the C612-1 small layer of the P26-1 water injection well group

[0087]

[0088] (2) Conduct dynamic connectivity assessment;

[0089] Clarify the perforation perfection P and water drive reserve control degree Z of each oil well k and the injection-production correspondence degree λ;

[0090] Wherein, perforation perfection degree P = perforated oil layer thickness / static connected thickness of oil layer;

[0091] Water drive reserve control degree Z k = Oil well perforation connected thickness / total oil layer thickness of oil well × 100%;

[0092] Injection-production correspondence degree λ = effective thickness of the oil well production layer connected to the water injection well / total effective thickness of the oil well production × 100%;

[0093] The relevant data are shown in Table 6;

[0094] Table 6 Statistics of dynamic status of oil and water wells in the small layer of C612-1 in the water injection well group of P26-1

[0095] hashtag Injection-production correspondence degree λ% <![CDATA[Water drive reserve control degree Z k %]]> Perforation perfection P% P26-1 (water injection well) — — 32.65 P26-2 99.3 100 100.00 P26-3 76.9 83.7 41.93 P26-4 97.6 100 61.74 P26-5 76.2 93.6 46.78 P26-6 45.0 99.9 49.97 P27-11 117.6 99.9 49.95

[0096] (3) The effective thickness h, porosity φ, permeability K, and static connectivity I of the sand body obtained above are 静 , perforation perfection P, water drive reserve control degree Z k The above evaluation parameters are normalized and weighted, and the sum of the products of the normalized evaluation parameters and their corresponding weights is used as the static and dynamic connectivity coefficient K. 连 ; That is: static and dynamic connectivity coefficient K 连 =0.11h+0.04φ+0.04K+0.16I 静 +0.27P+0.22Z k +0.162;

[0097] The relevant data are shown in Table 7 (the values in Table 7 are approximate values of the corresponding values in Tables 4 and 5);

[0098] Table 7 Calculation table of the potential for re-perforation of oil wells in the small layer of C612-1 in the P26-1 water injection well group

[0099]

[0100] The connectivity among wells P26-3, P26-5 and P26-6 is moderate, while the connectivity among wells P26-2, P26-4 and P27-11 is poor.

Claims

1. A method for analyzing the dynamic and static connectivity of sand bodies in oil and water wells, characterized by: Here’s how: (1) Conducting static connectivity assessment; Step 1-1: Determine the formation thickness H, effective sand body thickness h, porosity φ and permeability K of each production well with the water injection well as the center of the production and injection well group; Step 1-2: Divide the effective thickness of the sand body h by the formation thickness H to obtain the sand-to-formation ratio S; Step 1-3: Through interlayer characterization, the sand body distribution characteristics and vertical overlap relationship between the single sand bodies in the injection and production well group are obtained; according to the specific situation of the sand body distribution, the degree of connectivity of the sand body distribution I is obtained. h , according to the specific situation of longitudinal overlap, the degree of longitudinal overlap connectivity I is obtained z ; Step 1-4: Sand-to-ground ratio S, sand distribution connectivity degree I h and the degree of vertical overlapping connectivity I z The product of the static connectivity degree of the sand body I is obtained 静 ; (2) Conduct dynamic connectivity assessment; Clarify the perforation perfection P and water drive reserve control degree Z of each oil well k and the injection-production correspondence degree λ; (3) The effective thickness h, porosity φ, permeability K, and static connectivity I of the sand body obtained above are 静 , perforation perfection P, water drive reserve control degree Z k The above evaluation parameters are normalized and weighted, and the sum of the products of the normalized evaluation parameters and their corresponding weights is used as the static and dynamic connectivity coefficient K. 连 ; If the static and dynamic connectivity coefficient K 连 >0.76, indicating good inter-well connectivity; If the static and dynamic connectivity coefficient K 连 between 0.57 and 0.76, indicating moderate interwell connectivity; If the static and dynamic connectivity coefficient K 连 <0.57, indicating poor inter-well connectivity.

2. The method for analyzing the dynamic and static connectivity of sand bodies in oil and water wells according to claim 1, wherein: The static and dynamic connectivity coefficient K 连 The specific calculation formula is: Static and dynamic connectivity coefficient K 连 =A1×h+B1×φ+C1×K+D1×I 静 +Z k1 ×P+F1×Z k +G1×λ; Among them, A1 is the weight value of the effective thickness h of the sand body; B1 is the weight value of the porosity φ; C1 is the weight value of the permeability K; D1 is the static connectivity degree I of the sand body 静 The weight value of Z k1 is the weight value of the perforation perfection degree P; F1 is the water drive reserve control degree Z k G1 is the weight value of the injection-production degree λ.

3. The method for analyzing the dynamic and static connectivity of sand bodies in oil and water wells according to claim 2, wherein: The static and dynamic connectivity coefficient K 连 The specific calculation formula is: Static and dynamic connectivity coefficient K 连 =0.11h+0.04φ+0.04K+0.16I 静 +0.27P+0.22Z k +0.16λ.

4. The method for analyzing the dynamic and static connectivity of sand bodies in oil and water wells according to claim 3, wherein: The steps 1-3 obtain the longitudinal overlapping connectivity degree I z The specific process is: Among them, the sand body distribution characteristics are divided into lateral separation type, lateral butt joint type, lateral cut-over type and lateral replacement type according to the lateral contact mode; Among them, the lateral separation type is not connected; the lateral substitution type has poor connectivity; The lateral docking type includes underwater distributary channel underwater distributary channel and estuary bar-underwater distributary channel, both of which have medium connectivity; The lateral cut-overlapping type includes estuary bar-underwater diversion channel, underwater diversion channel-underwater diversion channel, underwater natural levee-underwater diversion channel and inter-diversion bay channel-underwater diversion channel; the estuary bar-underwater diversion channel has good connectivity, the underwater diversion channel-underwater diversion channel has good connectivity, the underwater natural levee-underwater diversion channel has poor connectivity, and the inter-diversion bay channel-underwater diversion channel has no connectivity; Among them, the vertical overlapping relationship includes vertical separation, vertical superposition, vertical cut-overlap and vertical substitution. Among them, the vertical separation type has poor connectivity or even no connectivity, the vertical superposition type has medium connectivity, the vertical cut-overlap type has good connectivity, and the vertical substitution type has good connectivity. Good connectivity is assigned a value of 1, medium connectivity is assigned a value of 0.79, and poor connectivity is assigned a value of 0.

5.

5. The method for analyzing the dynamic and static connectivity of sand bodies in oil and water wells according to claim 4, characterized in that: The static connectivity degree of the sand body is obtained in steps 1-4. 静 The specific process is: Sand body static connectivity degree I 静 =S×I h ×I z .

6. The method for analyzing the dynamic and static connectivity of sand bodies in oil and water wells according to claim 5, characterized in that: Perforation perfection degree P, water drive reserve control degree Z k The specific solution process of the injection-production correspondence degree λ is as follows: Perforation perfection degree P = perforated oil layer thickness / static connected thickness of oil layer; Water drive reserve control degree Z k = Oil well perforation connected thickness / total oil layer thickness of oil well × 100%; Injection-production correspondence degree λ = effective thickness of the oil well production layer connected to the water injection well / total effective thickness of the oil well production × 100%.

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