A method for quantitatively identifying different types of sand bodies in a distributary channel sand reservoir

Abstract

A quantitative identification method for different types of genetic sand bodies in distributary channel sand reservoirs relates to the field of oil and gas exploration and development technology, solving the problem of significant discrepancies between existing channel microfacies characterization results based on well logging facies models and effective thickness and the actual effects of oilfield development. The method includes: S1, preprocessing basic data; S2, determining the average sandstone thickness and average effective thickness of a certain layer in the study block based on well logging interpretation results; S3, determining the quality evaluation index of genetic sand bodies in distributary channel sand reservoirs; and S4, identifying different types of genetic sand bodies based on the determined quality evaluation index. This identification method can quantitatively calculate the quality evaluation index of sand bodies in different layers using conventional well logging interpretation data, and can quantitatively and quickly determine the genetic sand body type of a single well and a single layer, thereby describing the planar distribution characteristics of different types of genetic sand bodies and guiding oilfield adjustments and remaining oil potential tapping.

Description

Technical Field

[0001] This invention relates to the field of oil and gas exploration and development technology, and in particular to a method for quantitative identification of different types of genetic sand bodies in distributary channel sand reservoirs. Background Technology

[0002] The Changyuan peripheral oilfield is mainly composed of fluvial-deltaic sediments, with the channel sand reservoirs of the deltaic distributary plain subfacies accounting for 54.9% of the total proven reserves and being one of the main oil-producing strata. The channels in these channel sand reservoirs change rapidly in planar terms and are also subject to river erosion, resulting in strong heterogeneity both planarly and intra-strata. In the early stages of oilfield development, different types of microfacies were classified according to typical logging facies models and effective thicknesses, achieving good results. However, with further development, problems such as significant differences in development effects for the same microfacies and uneven planar utilization have emerged. Therefore, it is crucial to conduct detailed characterization of the genetic sand bodies in the channel sand reservoirs, clarify the causes of differences in development effects among channel sand microfacies, and guide oilfield development strategies to improve the overall development efficiency of the block and the oilfield.

[0003] Currently, existing methods mainly have the following two problems:

[0004] (1) The channel sands in the delta distributary plain are affected by topography, climate and river modification during their formation. The internal structure of the channel sand layers formed in different locations varies greatly. Existing methods describe the planar distribution of channel sands according to typical well logging facies models and extrapolation methods based on known well points. However, these methods cannot characterize the degree of river modification of the sand body, and the characterization results differ greatly from the actual effects of oilfield development.

[0005] (2) During the oilfield development process, the difference between the plane and the in-layer permeability is the main controlling factor affecting the distribution of remaining oil in the channel sand reservoir and the development effect. Existing methods can no longer characterize the permeability of channel sand and the degree of interlayer development at different locations, thus affecting the evaluation of development effect and the tapping of remaining oil.

[0006] For the two reasons mentioned above, the results of channel microfacies characterization based on well logging facies models and effective thickness differ significantly from the actual effects of oilfield development. They cannot effectively guide the analysis of oilfield or block development status, nor can they effectively guide the adjustment of oilfield or block development, making it difficult to meet the needs of fine-tuning the potential of channel sand reservoirs in the middle and late stages of development. Summary of the Invention

[0007] This invention addresses the problem in the prior art where existing channel microfacies characterization results based on well logging facies models and effective thickness differ significantly from actual oilfield development results. It provides a quantitative identification method for different types of genetic sand bodies in distributary channel sand reservoirs. This method can quantitatively calculate the quality evaluation index of sand bodies in different layers using conventional well logging interpretation data. It can quantitatively and rapidly determine the genetic sand body type of a single well or layer, thereby describing the planar distribution characteristics of different types of genetic sand bodies and guiding oilfield adjustments and remaining oil potential tapping.

[0008] The present invention solves its problem through the following technical solution: A method for quantitative identification of different types of genetic sand bodies in distributary channel sand reservoirs, comprising the following steps:

[0009] S1. Obtain basic data and preprocess the basic data;

[0010] S2. Based on the well logging interpretation results, determine the average sandstone thickness h of a certain layer in the study block. sb and average effective thickness h eb ;

[0011] S3. Determine the genesis and sand body quality evaluation index of the distributary channel sand reservoir. h ;

[0012] S4. Sand quality evaluation index I based on the determined genesis of the distributary channel sand reservoir. h Identify different types of sand bodies of different origins.

[0013] Furthermore, the method for preprocessing basic data in step S1 includes: interpreting the basic data of a single well using well logging, identifying the sand body sedimentary microfacies type based on the block well logging facies model, and obtaining h. si h sei h ei and h fi Establish a basic data table for evaluating river sand reservoirs.

[0014] Furthermore, the S1 basic data includes the sedimentary microfacies type of the single-well sand body, sandstone thickness, oil layer sandstone thickness, effective oil layer thickness, and interlayer thickness.

[0015] Furthermore, step S2 determines the average sandstone thickness h of a certain well layer in the study block. sb and average effective thickness h eb The method is as follows:

[0016] Based on the obtained sandstone thickness of all sandstone bodies in a certain layer, the average sandstone thickness h of that layer is calculated. sb ;

[0017] Based on the effective thickness of the oil reservoir from all wells in a given layer, the average effective thickness h of that layer is calculated.eb .

[0018] Furthermore, in step S3, the sand body quality evaluation index I h Indicating the size of the sand body and the degree of interlayer development; Sand body quality evaluation index I h The larger the value, the larger the sand body and the better the homogeneity of the reservoir.

[0019] Furthermore, step S3 determines the quality evaluation index I of the genetic sand bodies in the distributary channel sand reservoir. h Methods for identifying different types of genetic sand bodies include:

[0020] Based on the sand body quality evaluation index, the sand bodies in the study area are divided into channel sand and interchannel sand;

[0021] I h When the value is greater than 0, the sand body in the study area is a river channel;

[0022] I h When =0, the sand body in the study area is interchannel sand.

[0023] Furthermore, based on the range of values ​​for the sand quality evaluation index, the river channel can be divided into three levels, namely:

[0024] I h >3, the river channel is a Class I river channel;

[0025] 2≤I h ≤3, the river channel is a Class II river channel;

[0026] 0 < I h <2, the river is a Class III river.

[0027] Furthermore, Class I rivers have strong sediment-carrying and transformation capabilities, large sand bodies with great thickness, underdeveloped interlayers, and weak heterogeneity within the sand body layers;

[0028] Class II rivers have a strong sand-carrying capacity but a weak ability to be modified. The sand bodies are large in scale and thickness, and are prone to forming muddy interlayers. The sand body layers are highly heterogeneous.

[0029] Furthermore, Class III rivers have weak sediment-carrying and transformation capabilities, and the sand bodies are small in size and thickness.

[0030] Furthermore, in step S3, the quality evaluation index I of the genetic sand body of the diversion channel sand reservoir is... h The formula is:

[0031]

[0032] In the formula: I h This is a dimensionless index for evaluating the quality of sand bodies in a certain well formation.

[0033] i represents a sand body in a certain well formation, dimensionless; n represents n channel sand bodies in a certain well formation, dimensionless;

[0034] α i is the sedimentary microfacies index of a sand body in a certain well layer. The well logging facies of the sand body is 1 for channel time and 0 for interchannel sand time, and is dimensionless.

[0035] h fi The thickness of the interlayer in a certain well formation is expressed in meters (m).

[0036] g sei The effective sandstone thickness of a certain well formation is expressed in meters (m).

[0037] h si The thickness of the sandstone layer in a certain well is expressed in meters (m).

[0038] h sb The average thickness of a certain sandstone layer is expressed in meters (m).

[0039] g ei The effective thickness of the oil layer in a certain well formation is expressed in meters (m).

[0040] g eb The average effective thickness of a certain layer, in meters;

[0041] All parameters can be obtained from the logging interpretation data of the production well.

[0042] Compared with the above-mentioned background technology, the present invention has the following beneficial effects:

[0043] This invention provides a quantitative identification method for different types of genetic sand bodies in distributary channel sand reservoirs. It can further subdivide channel microfacies into genetic channel sand bodies of type I, type II, and type III using conventional well logging interpretation data, further clarify the planar distribution characteristics of different types of genetic sand bodies, improve the effectiveness of reservoir measures and the degree of reserve mobilization, and improve the oilfield development effect.

[0044] This invention presents a quantitative identification method for different types of genetic sand bodies in distributary channel sand reservoirs. For the first time, it considers the channel size and interlayer development degree of distributary channel sand reservoirs, enabling quantitative and rapid identification of genetic sand body types in individual wells and layers. The single sand body distribution map drawn using the genetic sand body type identification results more closely conforms to sedimentary patterns, more accurately describes the heterogeneity characteristics of the reservoir, accurately reflects the connectivity quality between oil and water wells, and has a better correspondence with the actual development of oilfields or blocks. The results can be applied to tapping remaining oil potential in oilfields and improving reservoir utilization, providing a scientific basis for improving oilfield development outcomes. Attached Figure Description

[0045] Figure 1 This is a flowchart of the method for quantitative identification of different types of genetic sand bodies in diversion channel sand reservoirs according to the present invention;

[0046] Figure 2 This is a parameter model of a sand body of a certain well formation according to an embodiment of the present invention. Detailed Implementation

[0047] To make the objectives, technical solutions, and advantages of the present invention clearer, the embodiments of the present invention will be described in further detail below with reference to the accompanying drawings.

[0048] Figure 1 This is a flowchart illustrating the method for quantitative identification of different types of genetic sand bodies in diversion channel sand reservoirs according to the present invention; for example... Figure 1 As shown, a method for quantitative identification of different types of genetic sand bodies in distributary channel sand reservoirs includes: S1, acquiring basic data and preprocessing the basic data; S2, determining the average sandstone thickness h of a certain sand body in the study block based on well logging interpretation results. sb and average effective thickness h eb S3. Determine the sand body quality evaluation index I for the genesis of the distributary channel sand reservoir. h S4. Quality evaluation index I based on the determined genesis of the distributary channel sand reservoir. h Identify different types of sand bodies of different origins.

[0049] This invention provides a method for quantitative identification of different types of genetic sand bodies in distributary channel sand reservoirs, specifically including the following steps:

[0050] S1. Obtain basic data and preprocess the basic data;

[0051] The basic data includes the sedimentary microfacies type, sandstone thickness, effective sandstone thickness, effective oil layer thickness, and interlayer thickness of a single well.

[0052] Well logging interpretation was performed on the sandstone thickness, effective sandstone thickness, effective oil layer thickness, and interlayer thickness of a single well. Based on the block's well logging facies model, the sedimentary microfacies of the sand body were identified, and the sedimentary microfacies type and sandstone thickness h of a specific well layer were obtained. si Effective sandstone thickness h sei Effective oil layer thickness h ei and interlayer thickness h fi ;

[0053] For example, to facilitate subsequent formula calculations, a basic data table for evaluating channel sand reservoirs can be established.

[0054] S2. Based on the well logging interpretation results, determine the average sandstone thickness g of a certain sand body in the study block. sb and average effective thickness h eb ;

[0055] Based on the obtained sandstone thickness of all sandstone bodies in a certain layer, the average sandstone thickness h of that layer is calculated. sb ;

[0056] Based on the effective thickness of the oil reservoir from all wells in a given layer, the average effective thickness h of that layer is calculated. eb .

[0057] S3. Determine the genesis and sand body quality evaluation index of the distributary channel sand reservoir. h ;

[0058] Read the well logging interpretation data of a certain sand body in steps S1 and S2, and calculate the sand body quality evaluation index I. h .

[0059] I h The sand body quality evaluation index can indicate the size of the sand body and the degree of interlayer development. The larger the index, the larger the sand body and the better the homogeneity of the reservoir.

[0060] The step S3, the sand body quality evaluation index of the diversion channel sand reservoir, is described in section I. h The formula is:

[0061]

[0062] In the formula: I h This is a dimensionless index for evaluating the quality of sand bodies in a certain well formation.

[0063] i represents a sand body in a certain well formation, dimensionless; n represents n channel sand bodies in a certain well formation, dimensionless;

[0064] α i is the sedimentary microfacies index of a sand body in a certain well layer. The well logging facies of the sand body is 1 for channel time and 0 for interchannel sand time, and is dimensionless.

[0065] h fi The thickness of the interlayer in a certain well formation is expressed in meters (m).

[0066] h sei The effective sandstone thickness of a certain well formation is expressed in meters (m).

[0067] h si The thickness of the sandstone layer in a certain well is expressed in meters (m).

[0068] h sb The average thickness of a certain sandstone layer is expressed in meters (m).

[0069] h ei The effective thickness of the oil layer in a certain well formation is expressed in meters (m).

[0070] h eb The average effective thickness of a certain layer, in meters;

[0071] All parameters can be obtained from the logging interpretation data of the production well.

[0072] S4. Sand quality evaluation index I based on the determined genesis of the distributary channel sand reservoir. h Identify different types of sand bodies of different origins;

[0073] Based on the sand body quality evaluation index, the sand bodies in the study area are divided into channels (I) and waterways (I). h >0) and inter-channel sand (I h =0).

[0074] Rivers can be classified into Class I rivers (I h >3) Class II waterways (2≤I) h ≤3), Class III waterways (0 < I) h <2) Three levels.

[0075] Class I rivers have strong sediment carrying and transformation capabilities, large sand bodies with great thickness, poor interlayer development, and weak heterogeneity within the sand body layers;

[0076] Class II rivers have a strong sand-carrying capacity but a weak ability to be modified. The sand bodies are large in scale and thickness, and are prone to forming muddy interlayers. The sand body layers are highly heterogeneous.

[0077] Class III rivers have weak sediment carrying and transformation capabilities, and the sand bodies are small in size and thickness.

[0078] Example 1

[0079] To make the objectives, technical solutions, and advantages of this invention clearer, the following description, using the FⅡ12 sedimentary unit of well group C5 in a certain block of Chaoyangou Oilfield as an example, will be further detailed with reference to the accompanying drawings.

[0080] A method for quantitative identification of different types of genetic sand bodies in distributary channel sand reservoirs, specifically including the following steps:

[0081] Step 1: Obtain basic data and preprocess it;

[0082] Taking the FⅡ12 sedimentary unit of well C5 in a certain block of the Chaoyangou oilfield as the object, the GPTlog software was used to interpret the sandstone thickness, oil-bearing sandstone thickness, effective oil layer thickness, and interlayer thickness of the single well. Based on the block's logging facies model, sandstone sedimentary microfacies were identified, and the sandstone thickness h was obtained. si Effective sandstone thickness h sei Effective oil layer thickness h ei and interlayer thickness h fi .

[0083] For example, to facilitate subsequent formula calculations, a basic data table for the evaluation of channel sand reservoirs can be established; the statistical data of the basic data for the evaluation of sand bodies in the FⅡ12 sedimentary unit of well C5 in a certain block of Chaoyangou oilfield is shown in Table 1.

[0084] The parameter model of the sand body of a certain well formation is attached. Figure 2 .

[0085] Table 1. Basic Data for Sand Body Evaluation in Sedimentary Unit FⅡ12 of Well Group C5 in a Block of Chaoyangou Oilfield

[0086]

[0087] Step 2: Based on the well logging interpretation results, calculate the average sandstone thickness h of a certain sand body. sb and average effective thickness h eb ;

[0088] Based on well logging interpretation results, the average sandstone thickness h of a certain sand body in a certain layer of the Fuyu oil reservoir in a certain block was calculated. sb and average effective thickness h eb , used for calculations in the following formulas.

[0089] Step 3: Calculate the quality evaluation index I of the genetic sand body of the distributary channel sand reservoir. h Values ​​are used to identify different types of sand bodies.

[0090] Read the well logging interpretation data of a certain sand body in step one and step two, and calculate the sand body quality evaluation index I. h I h The sand body quality evaluation index can indicate the size of the sand body and the degree of interlayer development. The larger the index, the larger the sand body and the better the homogeneity of the reservoir.

[0091] Based on the sand body quality evaluation index, the sand bodies in the study area are divided into channels (I) and waterways (I). h >0) and inter-channel sand (I h =0), where the river can be divided into Class I river (I h >3) Class II waterways (2≤I) h ≤3), Class III waterways (0 < I) h <2) Three levels.

[0092] Class I rivers have strong sediment carrying and transformation capabilities, large sand bodies with great thickness, poor interlayer development, and weak heterogeneity within the sand body layers;

[0093] Class II rivers have a strong sand-carrying capacity but a weak ability to be modified. The sand bodies are large in scale and thickness, and are prone to forming muddy interlayers. The sand body layers are highly heterogeneous.

[0094] Class III rivers have weak sediment carrying and transformation capabilities, and the sand bodies are small in size and thickness.

[0095] Table 2 shows the sand body quality evaluation data of the FⅡ12 sedimentary unit of well C5 in a certain block of Chaoyangou Oilfield.

[0096] Table 2. Sand body quality evaluation data of FⅡ12 sedimentary unit in well C5 group of a certain block in Chaoyangou Oilfield.

[0097]

[0098] This invention presents a quantitative identification method for different types of genetic sand bodies in distributary channel sand reservoirs. For the first time, it considers the channel size and interlayer development of distributary channel sand reservoirs, enabling quantitative and rapid identification of genetic sand body types. The single sand body distribution map drawn using the genetic sand body type identification results more closely conforms to sedimentary patterns, more accurately describes the heterogeneity of the reservoir, accurately reflects the connectivity quality between oil and water wells, and has a better correlation with the actual development of oilfields or blocks. The results can be applied to tapping remaining oil potential in oilfields and improving reservoir utilization.

[0099] Those skilled in the art will recognize that the embodiments described herein are intended to help the reader understand the implementation methods of the present invention, and should be understood that the scope of protection of the present invention is not limited to such specific statements and embodiments. Those skilled in the art can make various other specific modifications and combinations based on the technical teachings disclosed in this invention without departing from the spirit of the invention, and these modifications and combinations are still within the scope of protection of the present invention.

Claims

1. A method for quantitative identification of different types of genetic sand bodies in distributary channel sand reservoirs, characterized in that: Includes the following steps: S1. Obtain basic data and preprocess the basic data; S2, according to the logging interpretation results, determine the average sandstone thickness h of a certain layer in the study block sb and the average effective thickness h eb ; S3, determining a quality evaluation index I of the genetic sand body of the distributary channel sand reservoir h ; S4. Based on the determined quality evaluation index I of the distributary channel sand reservoir genetic sand body h , different types of genetic sand bodies are identified.

2. The method for quantitative identification of different types of genetic sand bodies in distributary channel sand reservoirs according to claim 1, characterized in that: The method for preprocessing the basic data in step S1 includes: The basic data of single well are interpreted by well logging, the sand body sedimentary microfacies types are identified according to the block well logging facies model, and the sedimentary microfacies types of the sand body of a well layer, the thickness h of the sand body of a well layer si , the effective sandstone thickness h of a well layer sei , the effective thickness h of an oil layer of a well layer ei and the interlayer thickness h of a well layer fi are obtained. The sedimentary microfacies type and sandstone thickness h of a certain well formation sand body were obtained. si Effective sandstone thickness h sei Effective oil layer thickness h ei and interlayer thickness h fi Establish a basic data table for reservoir sand body evaluation.

3. The method for quantitative identification of different types of genetic sand bodies in a distributary channel sand reservoir according to claim 1 or 2, characterized in that: The S1 basic data includes the sedimentary microfacies type, sandstone thickness, effective sandstone thickness, effective oil layer thickness, and interlayer thickness of a single well.

4. The method for quantitative identification of different types of genetic sand bodies in a distributary channel sand reservoir according to claim 1, characterized in that: Step S2 determines the average sandstone thickness h of a certain layer in the study block. sb and average effective thickness h eb The method is as follows: Based on the obtained sandstone thickness of all sandstone bodies in a certain layer, the average sandstone thickness h of that layer is calculated. sb ; Based on the effective thickness of the oil reservoir from all wells in a given layer, the average effective thickness h of that layer is calculated. eb .

5. The method for quantitative identification of different types of genetic sand bodies in a distributary channel sand reservoir according to claim 1, characterized in that: In step S3, the sand quality evaluation index I h Indicating the size of the sand body and the degree of interlayer development; Sand body quality evaluation index I h The larger the value, the larger the sand body and the better the homogeneity of the reservoir.

6. The method for quantitative identification of different types of genetic sand bodies in a distributary channel sand reservoir according to claim 1, characterized in that: Step S3 determines the sand body quality evaluation index I for the genealogy of the distributary channel sand reservoir. h Methods for identifying different types of sand bodies include: Based on the sand body quality evaluation index, the sand bodies in the study area are divided into channel sand and interchannel sand; I h When the value is greater than 0, the sand body in the study area is a river channel; I h When =0, the sand body in the study area is interchannel sand.

7. The method for quantitative identification of different types of genetic sand bodies in a distributary channel sand reservoir according to claim 1, characterized in that: The river channel is divided into three levels based on the range of sand quality evaluation index values: I h >3, the river channel is a Class I river channel; 2≤I h ≤3, the river channel is a Class II river channel; 0 < I h <2, the river is a Class III river.

8. The method for quantitative identification of different types of genetic sand bodies in a distributary channel sand reservoir according to claim 7, characterized in that: The Class I rivers have strong sediment carrying and transformation capabilities, large sand bodies with great thickness, poor interlayer development, and weak heterogeneity within the sand body layers. The Class II rivers have a strong sand-carrying capacity but a weak ability to be modified. The sand bodies are large in scale and thickness, and are prone to forming muddy interlayers. The sand body layers are highly heterogeneous.

9. The method for quantitative identification of different types of genetic sand bodies in a distributary channel sand reservoir according to claim 7, characterized in that: The Class III rivers have weak sediment carrying and transformation capabilities, and the sand bodies are small in size and thickness.

10. A method for quantitative identification of different types of genetic sand bodies in a distributary channel sand reservoir according to claim 1, 6, or 7, characterized in that: The step S3, the sand body quality evaluation index of the diversion channel sand reservoir, is described in section I. h The formula is: In the formula: I h This is a dimensionless index for evaluating the quality of sand bodies in a certain well formation. i represents a sand body in a certain well formation, dimensionless; n represents a well formation containing n channel sand bodies, dimensionless. α i is the sedimentary microfacies index of a sand body in a certain well formation. The well logging facies of the sand body is 1 for channel time and 0 for interchannel sand time, and is dimensionless. h fi The thickness of the interlayer in a certain well formation is expressed in meters (m). h sei The effective sandstone thickness of a certain well formation is expressed in meters (m). h si The thickness of the sandstone layer in a certain well is expressed in meters (m). g sb The average thickness of a certain sandstone layer, in meters; g ei The effective thickness of the oil layer in a certain well formation is expressed in meters (m). h eb The average effective thickness of a certain layer, in meters; All parameters can be obtained from the logging interpretation data of the production well.

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