A method, medium and device for establishing a velocity field through step-by-step matching of well-to-seismic horizons

Abstract

The application discloses a well-seismic layer step-by-step matching velocity field establishment method, which comprises the following steps: preparing logging data, seismic data and the like, making a seismic synthetic record to obtain a time-depth curve TD1, using the initial time-depth curve TD1 to interpolate and establish a preliminary velocity field V1, using the first velocity field V1 to perform top and bottom layering depth-time conversion of a target layer, obtaining a target layer top and bottom surface seismic horizon H 顶 and H 底 , determining a corrected time-depth curve TD2 of each well, using the time-depth curve TD2 to establish a velocity field V2, using the velocity field V2 to perform unit level layering depth-time conversion in the target layer, obtaining each sedimentary unit top surface seismic horizon H d1 , H d2 ……H dn , obtaining a final time-depth curve TD3 of each well, and using the time-depth curve TD3 to establish a final velocity field V3.The method of the application is based on multi-well consistency analysis, and solves the problem of low precision of a three-dimensional velocity field in seismic structure interpretation.

Description

TECHNICAL FIELD

[0001] The present application relates to a reservoir prediction research method, and belongs to the field of oilfield reservoir prediction, in particular to a well-seismic layer step-by-step matching velocity field establishment method, medium and equipment. BACKGROUND

[0002] In the late stage of oilfield development, the remaining oil is mainly enriched in imperfect injection-production areas, such as fault edge and local structural high. The fault edge well distribution and horizontal well tapping methods have become common tapping methods, which require higher and higher seismic structure precision, and a high-precision velocity field establishment method is needed to adapt to it.

[0003] At present, the commonly used three-dimensional velocity field establishment method for developing earthquakes is to establish a velocity field by using well point time-depth relationship interpolation under the constraint of seismic layer. This method has the following two shortcomings: first, the seismic layer used for trend constraint and the corresponding well point geological layer are not completely matched (only part of the well layer can be matched with the seismic layer), because the quality of the synthetic seismogram is determined by the waveform matching degree of the synthetic seismogram and the well seismic trace, not by the matching between the well layer and the seismic layer; second, the seismic layer used for trend constraint is less, generally at the oil layer group level or individual geological interface with obvious reflection characteristics on the seismic profile, this method cannot obtain the sedimentary unit level seismic layer, and thus cannot achieve sedimentary unit level layer matching and constraint.

[0004] Therefore, how to improve the precision of the velocity field has become a problem to be solved in the field. SUMMARY

[0005] In view of the above problems, the present application provides a well-seismic layer step-by-step matching velocity field establishment method, medium and equipment, which can effectively improve the seismic structure interpretation precision based on multi-well consistency analysis, and guarantee the remaining oil tapping effect.

[0006] To achieve the above technical purposes, the technical scheme adopted by the present application is as follows:

[0007] According to one aspect of the present application, a well-seismic layer step-by-step matching velocity field establishment method is provided, which comprises the following steps:

[0008] Step 1: preparing the well logging data, seismic data and target layer top and bottom surface seismic layer data h 顶 and h 底 of the target well site;

[0009] Step 2: obtaining the initial time-depth curve TD1 of each well by making a seismic synthetic record;

[0010] Step 3: obtaining the target layer top and bottom surface seismic layer data h 顶 and h底 Under the trend constraint, the first velocity field V1 is established by using the initial time-depth curve TD1 of the well point;

[0011] Step 4: The top and bottom of the target layer are divided by using the first velocity field V1. 深顶、 top 深底 The depth domain is converted to the time domain. 时顶、 top 时底 ;

[0012] Step 5: Under the trend constraint of the top and bottom of the target layer, the new top and bottom seismic horizons H and H are obtained by interpolating the top and bottom of the target layer in the time domain. 时顶、 top 时底 顶1 底1 The consistency analysis and abnormal value processing are respectively performed on H and H to obtain the final top and bottom seismic horizons H and H. 顶1 底1 顶 底 ;

[0013] Step 6: The time-depth pair T-D is obtained by matching the top and bottom of the target layer in the depth domain top and top with the final top and bottom seismic horizons H and H obtained in step 5, and the initial time-depth curve TD1 is corrected to obtain the corrected time-depth curve TD2 of each well. 深顶、 top 深底 顶 底 ;

[0014] Step 7: Under the trend constraint of the final top and bottom seismic horizons H and H, the second velocity field V2 is established by using the corrected time-depth curve TD2. 顶 底

[0015] Step 8: The top and bottom of the target layer in the depth domain are converted to the time domain by using the second velocity field V2. 深1 top 深 2......top 深n 时1 top 时2 ......top 时n ;

[0016] Step 9: Under the trend constraint of the final top and bottom seismic horizons H and H of the target layer, the top and bottom of the target layer in the time domain are divided. 顶 top 底 时1 top 时2 ......top 时n ​​​​​​​​​​​Interpolation yields seismic horizons H1, H2...H at the top of each sedimentary unit within the initial target layer. n For H1, H2...H n Consistency analysis and outlier processing were performed separately to obtain the final seismic horizon H of the top surface of each sedimentary unit within the target layer. d1 H d2 ......H dn ;

[0017] Step 10: Utilize depth-domain depositional unit-level stratification within the target layer top 深1 top 深2 ......top 深n The bottom layer of the target layer and the seismic horizon H of the top surface of each sedimentary unit within the final target layer obtained in step 9. d1 H d2 ......H dn H 底 The corresponding matching yields the final time-depth curve TD3 for each well;

[0018] Step 11: Seismic horizon H at the top surface of each sedimentary unit within the final target layer. d1 H d2 ......H dn H 底 Under trend constraints, the third velocity field V3 is established by interpolation of the final time-depth curve TD3.

[0019] According to one embodiment of the present invention, the data in step 1 is obtained through conventional well logging interpretation and seismic tectonic interpretation.

[0020] According to an embodiment of the present invention, step 2 includes: calculating the reflection coefficient from the acoustic wave and density logging curves, convolving the reflection coefficient with the extracted seismic wavelet to obtain an initial synthetic seismic record, matching and adjusting the initial synthetic seismic record with the well-side seismic trace to obtain a final synthetic seismic record, and each depth point on the final synthetic seismic record corresponds to a time value, thereby obtaining the initial time-depth curve TD1 for each well.

[0021] According to one embodiment of the present invention, step 3 includes: dividing the target layer into n smaller layers in the time domain at equal proportions, each smaller layer having a thickness of d, then:

[0022] d=(h 底 -h 顶 ) / n

[0023] Among them, h 底 and h 顶 These are the top and bottom seismic horizons of the target layer obtained from seismic tectonic interpretation, where n represents the number of sub-layers of the target layer;

[0024] In h 顶 and h 底 We obtain n-1 seismic horizons, and calculate the seismic horizon h of each sub-layer. i :

[0025] h i =h 顶 +i*d

[0026] Where i represents the nth sub-layer, 1≤i≤n-1;

[0027] Based on the initial time-depth curve TD1, each well in the time domain is correlated with the seismic horizon h. i The time-depth pairs at the intersection points are extracted and inter-well interpolation is performed to obtain the small layer h. i planar velocity V i When n is large enough, h i Planar velocity V i It's h i The velocity of the layer is used to obtain the first velocity field V1 of the target layer.

[0028] According to one embodiment of the present invention, step 4 includes: obtaining t = 2h / v according to h = vt / 2, where t is the seismic double-layer travel time, h is the depth, and v is the velocity; and using the formula t = 2h / v through the first velocity field V1, separating the top and bottom layers of the target layer. 深顶、 top 深底 Transformation from depth domain to time domain top 时顶、 top 时底 .

[0029] According to one embodiment of the present invention, step 5 includes: using two wells spaced at a predetermined distance as boundaries, interpolating to obtain new top and bottom seismic horizons H. 顶1 and H 底1 .

[0030] According to one embodiment of the present invention, when the distance between two wells is greater than a predetermined distance, the inter-well stratification interpolation trend is based on the seismic horizon trend; when the distance between two wells is less than the predetermined distance, the inter-well trend is based on the time-domain stratification interpolation trend of the two wells.

[0031] According to an embodiment of the present invention, in step 5, H... 顶1 and H 底1 Consistency analysis and outlier handling were performed separately. This included: when the time-domain stratification of an individual well differed significantly from that of nearby wells, resulting in anomalous protrusions or depressions on the newly interpolated seismic horizons, and when the well location was inconsistent with the overall trend of the seismic horizons, outlier removal or smoothing was performed on that well location to obtain the final top and bottom seismic horizons H. 顶 and H 底 .

[0032] According to one embodiment of the present application, step 6 comprises: using the top surface layering of the oil reservoir group at the well point in the depth domain to match the final top surface seismic horizon H 顶 carrying out matching to obtain the top and bottom interface time-depth pairs T-D, and using the time-depth pairs T-D to correct the initial time-depth curve TD1 to obtain the corrected time-depth curve TD2 of each well. 底 carrying out matching to obtain the top and bottom interface time-depth pairs T-D, and using the time-depth pairs T-D to correct the initial time-depth curve TD1 to obtain the corrected time-depth curve TD2 of each well.

[0033] According to one embodiment of the present application, step 7 comprises: dividing the target horizon into n' small layers in the time domain according to equal proportion, and the thickness of each small layer is d', then:

[0034] d' = (H 底 -H 顶 ) / n'

[0035] wherein H 底 and H 顶 are the final top and bottom surface seismic horizons obtained in step 5, and n' represents the number of the divided small layers;

[0036] n'-1 seismic horizons are obtained between H 顶 and H 底 , and the seismic horizon H i of each small layer is obtained by calculation:

[0037] H i = H 顶 +i' * d'

[0038] wherein i' represents the number of the small layer, and 1≤i'≤n'-1;

[0039] Based on the corrected time-depth curve TD2, the time-depth pairs of the intersection points between each well in the time domain and the seismic horizon H i are extracted to obtain the plane velocity V i of the small layer H i by inter-well interpolation, and when n' is large enough, the plane velocity V i of the small layer H i is the velocity of the layer H i ', thereby obtaining the second velocity field V2 of the target horizon.

[0040] According to one embodiment of the present application, step 8 comprises: obtaining t = 2h / v according to h = vt / 2, wherein t is the seismic double-layer travel time, h is the depth, and v is the velocity, and converting the top and bottom layering of each sedimentary unit from the depth domain to the time domain by using the formula t = 2h / v according to the second velocity field V2.

[0041] According to one embodiment of the present application, step 9 comprises: top 时1 ...top 时2 ...top 时n top n .

[0042] According to one embodiment of the present application, when the distance between the two wells is greater than the second predetermined distance, the trend of the inter-well layering interpolation is based on the trend of the seismic horizon, and when the distance between the two wells is less than the second predetermined distance, the trend is based on the trend of the time-domain layering interpolation of the two wells.

[0043] According to one embodiment of the present application, the consistency analysis and the outlier processing of H1, H2,..., H n in step 9 respectively comprises: when the time-domain layering of an individual well is greatly different from that of the wells in the vicinity, an abnormal protrusion or depression appears on the interpolated new seismic horizon, and in the case that the position of the well is inconsistent with the overall trend of the seismic horizon, the final top surface seismic horizon H d1 , H d2 ... H dn of each depositional unit in the target layer is obtained by outlier rejection or smoothing processing of the position of the well.

[0044] According to one embodiment of the present application, step 10 comprises: top 深1 in the depth domain layering of the depositional unit in the target layer of the well point is matched with the top surface seismic horizon H d1 , top 深2 is matched with the seismic horizon H d2 ... top 深n is matched with the seismic horizon H dn , the bottom surface layering of the target layer is matched with H 底 , and n+1 sets of time-depth pairs are obtained. The final time-depth curve TD3 of each well is obtained by correcting the corrected time-depth curve TD2 using the n+1 sets of time-depth pairs.

[0045] According to one embodiment of the present application, step 11 comprises: each depositional unit level layer is subjected to the velocity calculation of each layer by applying the final time-depth curve TD3 according to the method of step 3, and the third velocity field V3 to be established is obtained when the velocity calculation of each layer of all depositional unit level layers is completed.

[0046] According to one embodiment of the present application, in step 10, the top of the reservoir group and the top of the first depositional unit are the same layering.

[0047] According to one embodiment of the present application, the number of sub-layers is determined according to the thickness of the target layer and the accuracy requirement of the velocity to be established in step 3 and step 5.

[0048] According to another aspect of the present application, a computer readable storage medium is provided, which stores a computer program, wherein the computer program is executed by a processor to perform the steps of the method as described above.

[0049] According to still another aspect of the present application, a computer device is provided, comprising:

[0050] at least one processor; and

[0051] a memory storing a computer program executable on the processor, wherein the processor executes the program to perform the steps of the method as described above.

[0052] By adopting the above technical solutions, the method, medium and device provided by the present application have at least one of the following beneficial effects compared with the prior art:

[0053] (1) The time-depth curve with good well-seismic layer consistency is obtained by performing step-by-step matching analysis and consistency correction on the well point geological layering and the seismic horizon, so that the high-precision velocity field of the target layer in the study area is obtained;

[0054] (2) The seismic horizon at the sedimentary unit level obtained in the velocity field acquisition process can be used for seismic attribute analysis, framework model establishment of seismic inversion, etc.;

[0055] (3) The high-precision velocity field obtained finally realizes the time-depth conversion of the seismic data volume, seismic horizon, etc., especially the time-depth conversion of the seismic inversion data volume, which can be used to guide the preparation of the measure scheme. BRIEF DESCRIPTION OF DRAWINGS

[0056] The accompanying drawings are included to provide a further understanding of the present application, and constitute a part of the specification, and together with the following detailed description, serve to explain the present application, but do not constitute a limitation on the present application. In the drawings:

[0057] Figure 1 An exemplary flowchart of the velocity field establishment method according to the step-by-step matching of well-seismic layer is shown;

[0058] Figure 2 A schematic diagram of the top and bottom surface seismic horizons H 顶 and H 底 of the target layer matched with the well layering obtained according to one embodiment of the present application is shown;

[0059] Figure 3A schematic diagram of a deposition unit level interface seismic horizon obtained according to one embodiment of the present application is shown.

[0060] Figure 4 A schematic diagram of a velocity field V3 established according to one embodiment of the present application is shown. DETAILED DESCRIPTION

[0061] In order to make the objects, technical solutions and advantages of the present application clearer, the present application will be further described in detail below with specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and not used to limit the present application.

[0062] Figure 1 A flow chart of a Venturi tube self-cleaning method according to the present application is shown.

[0063] As shown in the figure, the method generally comprises the following steps:

[0064] Step 1: preparing well logging data, seismic data and target layer top and bottom surface seismic horizon data h 顶 and h 底 of a target well site

[0065] Step 2: obtaining an initial time-depth curve TD1 of each well by making a seismic synthetic record;

[0066] Step 3: under the constraint of the target layer top and bottom surface seismic horizon data h 顶 and h 底 trend, a first velocity field V1 is established by interpolation using the well point initial time-depth curve TD1;

[0067] Step 4: the target layer top and bottom layers top 深顶、 top 深底 are converted from the depth domain to the time domain top 时顶 , top 时底 using the first velocity field V1;

[0068] Step 5: under the constraint of the target layer top and bottom surface seismic horizon trend, new top and bottom surface seismic horizons H 顶1 and H 底1 are obtained by interpolation of the time domain top and bottom layers top 时顶 , top 时底 , and consistency analysis and abnormal value processing are respectively performed on H 顶1 and H 底1 to obtain the final top and bottom surface seismic horizons H 顶 and H 底 ;

[0069] Step 6: the depth domain top and bottom surface layers top 深顶 , top深底 top and bottom seismic horizons H 顶 and H 底 The initial time-depth curve TD1 is corrected by using the time-depth pair T-D to obtain the corrected time-depth curve TD2 of each well;

[0070] Step 7: In the final top and bottom seismic horizons H 顶 and H 底 of the target layer, the second velocity field V2 is established by using the first corrected time-depth curve TD2 under the trend constraint;

[0071] Step 8: The depth domain sedimentary unit level layer top 深1 , top 深 2... top 深n of the target layer is converted to the time domain top 时1 , top 时2 ... top 时n by using the second velocity field V2;

[0072] Step 9: In the final top and bottom seismic horizons H 顶 and H 底 of the target layer, the initial top seismic horizons H1, H2... H n of each sedimentary unit in the target layer are obtained by interpolating the time domain sedimentary unit level layer top 时1 , top 时2 ... top 时n of the target layer under the trend constraint, and the consistent analysis and abnormal value processing are performed on H1, H2... H n to obtain the final top seismic horizons H d1 , H d2 ... H dn of each sedimentary unit in the target layer;

[0073] Step 10: The final time-depth curve TD3 of each well is obtained by using the depth domain sedimentary unit level layer top 深1 , top 深2 ... top 深n of the target layer, the bottom layer of the target layer and the final top seismic horizons H d1 , H d2 ... H dn , H 底 of each sedimentary unit in the target layer obtained in step 9;

[0074] Step 11: In the final top seismic horizons H d1 , H d2 ... Hdn , H 底 Under the trend constraint, the third velocity field V3 is established by using the final time-depth curve TD3 interpolation.

[0075] The specific operation examples of each step are described below.

[0076] In some embodiments, the data in step 1 is obtained through conventional well logging interpretation and seismic structural interpretation. The well logging interpretation can be obtained based on respective well logging information, such as but not limited to resistivity, spontaneous potential, acoustic velocity, rock volume density, etc. The seismic structural interpretation can be obtained based on respective seismic data, such as but not limited to using the reflection time, phase consistency, wave velocity, etc. kinematic information of seismic wave, studying the distribution range and fluctuation form of the stratum interface, the development of faults, and converting the travel time in the full screen of the seismic time section into the depth of the stratum interface, drawing the structure map.

[0077] In some embodiments, the specific operation of step 2 can include calculating the reflection coefficient from the acoustic and density logging curves, convolving the reflection coefficient with the extracted seismic wavelet to obtain the initial synthetic seismic record, matching and adjusting the initial synthetic seismic record with the seismic trace beside the well to obtain the final synthetic seismic record, and each depth point on the final synthetic seismic record corresponds to a time value, thereby obtaining the initial time-depth curve TD1 of each well.

[0078] In some embodiments, the specific operation of step 3 can include dividing the target layer into n small layers in the time domain according to the equal proportion, and the thickness of each small layer is d, then:

[0079] d=(h 底 -h 顶 ) / n

[0080] wherein h 底 and h 顶 are the top and bottom seismic horizons of the target layer obtained by seismic structural interpretation, n represents the number of small layers divided from the target layer, and the size of n can be determined according to the thickness of the target layer and the accuracy requirement of the velocity to be established;

[0081] n-1 seismic horizons are obtained between h 顶 and h 底 , and the seismic horizon h i of each small layer is calculated:

[0082] h i =h 顶 +i*d

[0083] wherein i represents the number of the small layer, and 1≤i≤n-1;

[0084] Based on the initial time-depth curve TD1, each well in the time domain is matched with the seismic horizon hi The time-depth pair (velocity) of the intersection point is extracted to obtain the sublayer h i of the plane velocity V i When n is large enough, h i of the plane velocity V i is the velocity of the layer h i , thereby obtaining the first velocity field V1 of the target layer.

[0085] In some embodiments, the specific operation of step 4 can include: obtaining t = 2h / v according to h = vt / 2, where t is the seismic double-layer travel time, h is the depth, and v is the velocity, and dividing the top and bottom of the target layer into layers top 深顶、 top 深底 by converting from the depth domain to the time domain top 时顶 , top 时底 .

[0086] In some embodiments, the specific operation of step 5 can include: taking two wells with a predetermined distance as boundaries, and obtaining new top and bottom seismic horizons H 顶1 and H 底1 by interpolation. For example, when the distance between the two wells is greater than a first predetermined distance, the interwell layer interpolation trend is based on the seismic horizon trend, and when the distance between the two wells is less than the first predetermined distance, the interwell trend is based on the time-domain layer interpolation trend of the two wells. The first predetermined distance can be 200-400 meters. The consistency analysis and outlier processing of H 顶1 and H 底1 respectively can include: when the individual well time-domain layer is significantly different from the layers of the wells near it, an abnormal protrusion or depression appears on the interpolated new seismic horizon, and in the case where the well position is inconsistent with the overall trend of the seismic horizon, the final top and bottom seismic horizons H 顶 and H 底 are obtained by outlier rejection or smoothing processing of the well position. The new horizon is basically consistent with the overall trend of the original horizon, and matches the well layer better than the original horizon.

[0087] In some embodiments, the specific operation of step 6 can include: matching the top surface layer of the oil reservoir group at the well point in the depth domain with the final top seismic horizon H 顶 , and matching the bottom surface layer of the oil reservoir group with the final bottom seismic horizon H 底 to obtain the time-depth pair T-D (velocity) of the top and bottom interfaces, and applying the time-depth pair T-D (velocity) to correct the initial time-depth curve TD1 to obtain the corrected time-depth curve TD2 of each well.

[0088] In some embodiments, step 7 may include: dividing the target layer into n' smaller layers in the time domain at equal proportions, with each smaller layer having a thickness of d', then:

[0089] d'=(H 底 -H 顶 ) / n'

[0090] Among them, H 底 and H 顶 These are the final top and bottom seismic horizons obtained in step 5, where n' represents the number of sub-layers.

[0091] In H 顶 and H 底 We obtain n'-1 seismic horizons, and calculate the seismic horizon H of each sub-layer. i :

[0092] H i =H 顶 +i'*d'

[0093] Where i' represents the nth sub-layer, 1≤i'≤n'-1;

[0094] Based on the corrected time-depth curve TD2, each well in the time domain is compared with the seismic horizon H. i The time-depth pairs at the intersection points are extracted and inter-well interpolation is performed to obtain the small layer H. i Planar velocity V i When n' is large enough, H i planar velocity V i 'That is H' i The velocity of the layer is used to obtain the second velocity field V2 of the target layer.

[0095] In some embodiments, the specific operation of step 8 may include: obtaining t = 2h / v according to h = vt / 2, where t is the seismic double-layer travel time, h is the depth, and v is the velocity, and using the second velocity field V2 to convert the top and bottom layers of each sedimentary unit from the depth domain to the time domain using the formula t = 2h / v.

[0096] In some embodiments, step 9 may include: using two wells spaced a second predetermined distance as boundaries, and performing top-level stratification of sedimentary units within the target layer in the time domain. 时1 top 时2 ......top 时n Interpolation yields seismic horizons H1, H2...H at the top of each sedimentary unit within the initial target layer. nWhen the distance between two wells is greater than the second predetermined distance, the inter-well stratigraphic interpolation trend is determined according to the seismic horizon trend; and when the distance between two wells is less than the second predetermined distance, the inter-well trend is determined according to the time-domain stratigraphic interpolation trend of the two wells. The second predetermined distance can be 200-400 meters. The H1, H2,..., Hn+1 are the top surfaces of the sedimentary units in the target layer of the wells. n The consistency analysis and the outlier processing can include: when the stratigraphic layer of an individual well in the time domain is greatly different from the stratigraphic layers of the wells in the vicinity, an abnormal protrusion or depression appears on the interpolated new seismic horizon, and the well position is inconsistent with the overall trend of the seismic horizon, the final top surface of each sedimentary unit in the target layer is obtained by performing outlier rejection or smoothing processing on the well position. d1 d2 dn The new horizon of each sedimentary unit is basically consistent with the overall trend of the original horizon, and is better matched with the stratigraphic layer of the well than the original horizon.

[0097] In some embodiments, the specific operation of step 10 can include: using the depth-domain stratigraphic layer top 深1 of the sedimentary unit in the target layer of the well point to match the top surface of the sedimentary unit with the seismic horizon H d1 , and using the stratigraphic layer top 深2 to match the seismic horizon H d2 ,..., and using the stratigraphic layer top 深n to match the seismic horizon H dn , and using the stratigraphic layer of the bottom surface of the target layer to match the horizon H 底 , to obtain n+1 sets of time-depth pairs, and using the n+1 sets of time-depth pairs to correct the corrected time-depth curve TD2 to obtain the final time-depth curve TD3 of each well.

[0098] In some embodiments, the specific operation of step 11 can include: applying the final time-depth curve TD3 to each sedimentary unit level layer segment to obtain the velocity of each layer according to the method of step 3, and when the velocities of all sedimentary unit level layer segments are obtained, the third velocity field V3 to be established is obtained.

[0099] In some embodiments, the top of the reservoir group and the top of the first sedimentary unit are the same stratigraphic layer in step 10.

[0100] In some embodiments, the number of small layers is determined according to the thickness of the target layer and the accuracy requirement of the velocity to be established in steps 3 and 5.

[0101] The application also provides a computer-readable storage medium storing a computer program, which, when executed by a processor, performs the steps of the method described above.

[0102] ​​The application also provides a computer device, which comprises at least one processor and a memory, and the memory stores a computer program capable of running on the processor. The processor executes the program to execute the steps of the method.

[0103] The following will take a certain block in Daqing Oilfield as an example to illustrate the implementation process of the method.

[0104] Step 1 - data preparation:

[0105] Prepare well data (logging curves, inclination, layered) of the study area, seismic data volume and top and bottom surface seismic horizon data (h 顶 and h 底 ) of the target layer.

[0106] Step 2 - obtaining time-depth curve TD1:

[0107] The reflection coefficient is calculated from the sonic and density logging curves, and the reflection coefficient is convolved with the extracted seismic wavelet to obtain the initial synthetic seismic record. The initial synthetic seismic record is matched and adjusted with the seismic trace beside the well to obtain the final synthetic seismic record. Each depth point on the synthetic record corresponds to a time value, so the initial time-depth relationship curve DT1 of the well point is obtained.

[0108] Step 3 - establishing a preliminary velocity field V1:

[0109] In the time domain, the target layer is divided into n small layers according to the equal proportion, and the thickness of each small layer is d, so:

[0110] d=(h 底 -h 顶 ) / n

[0111] In the formula, h 底 and h 顶 are the top and bottom surface seismic horizons of the target layer obtained by seismic structure interpretation, and n represents the number of small layers divided from the target layer. N can be determined according to the thickness of the target layer and the accuracy requirement of the velocity to be established;

[0112] Thus, n-1 seismic horizons are obtained between h 顶 and h 底 , and the seismic horizon h i of each small layer is calculated:

[0113] h i =h 顶 +i*d

[0114] Wherein, i represents the number of the small layer, and 1≤i≤n-1;

[0115] Based on the initial time-depth curve TD1, each well in the time domain is matched with the seismic horizon h iThe time-depth pairs at the intersection points are extracted and inter-well interpolation is performed to obtain the small layer h. i Planar velocity V i When n is large enough, h i Planar velocity V i It's h i The velocity of the layer is used to obtain the first velocity field V1 of the target layer.

[0116] Step 4 - Conversion of target layer top and bottom depths:

[0117] From h = vt / 2, we get t = 2h / v, where t is the seismic double-layer travel time, h is the depth, and v is the velocity. Using the first velocity field V1, we can separate the top and bottom layers of the target layer using the formula t = 2h / v. 深顶、 top 深底 Transformation from depth domain to time domain top 时顶、 top 时底 .

[0118] Step 5 - Determine the seismic horizon H at the top and bottom of the target layer that matches the well layer. 顶 and H 底 :

[0119] Using a 300m gap between two wells as a boundary, when the gap is greater than 300m, the inter-well stratigraphic interpolation trend is based on the seismic horizon trend; when the gap is less than 300m, the inter-well trend is based on the time-domain stratigraphic interpolation trend of the two wells. The new top and bottom seismic horizons H are obtained through interpolation. 顶1 and H 底1 ;

[0120] When the time-domain stratification of an individual well differs significantly from that of its neighboring wells, resulting in anomalous bulges or depressions on the newly interpolated seismic horizon, or when the overall trend of the seismic horizon at that well location is inconsistent with the overall trend of the seismic horizon, the final top and bottom seismic horizon H can be obtained by performing outlier removal and smoothing processes on that well location. 顶 and H 底 ( Figure 2 The new strata are generally consistent with the original strata, and the new strata match the well strata better than the original strata.

[0121] Step 6 - Determine the corrected time-depth curve TD2 for each well:

[0122] Application of deep-domain well point top surface stratification and seismic horizon H 顶 Matching, layering of the oil layer group bottom surface and seismic horizon H were performed. 底 Matching is performed to correct the initial time-depth curve TD1, resulting in the corrected time-depth curve TD2 for each well.

[0123] Step 7 - Establish the velocity field V2 using the time-depth curve TD2;

[0124] The specific method is basically the same as that in step 3, except that the seismic horizons (h 顶 and h 底 ) in step 3 are replaced by the seismic horizons (H 顶 and H 底 ) obtained by time-domain layering interpolation, and the initial time-depth curve TD1 is replaced by the corrected time-depth curve TD2, to obtain a second velocity field V2.

[0125] Step 8 - using the velocity field V2 to perform unit-level layering in the target layer and convert the depth into time;

[0126] The specific method is basically the same as that in step 4, except that the top and bottom interface layering in step 4 is replaced by all sedimentary unit-level layering, although the number of layers increases, the method is the same.

[0127] Step 9 - obtaining the seismic horizons (H d1 , H d2 ,..., H dn ) of the top surfaces of all sedimentary units in the target layer.

[0128] The specific method is basically the same as that in step 5, except that step 5 obtains the seismic horizons of the top and bottom surfaces of the target layer, while this step obtains the seismic horizons of all sedimentary unit-level interfaces (H Figure 3 ).

[0129] Step 10 - obtaining the final time-depth curve TD3 of each well:

[0130] Matching the sedimentary unit-level layering top 深1 in the target layer at the depth domain well point with the seismic horizons H d1 of the top surfaces of the sedimentary units, matching the layering top 深2 with the seismic horizons H d2 ,..., matching the layering top 深n with the seismic horizons H dn , matching the bottom surface layering of the target layer with H 底 , to obtain n+1 sets of time-depth pairs, using the n+1 sets of time-depth pairs to correct the corrected time-depth curve TD2, to obtain the final time-depth curve TD3 of each well.

[0131] Step 11 - using the time-depth curve TD3 to establish a final velocity field V3.

[0132] The specific method is basically the same as that in step 3, except that on the basis of step 3, each sedimentary unit-level layer is further refined, and the time-depth curve TD3 is applied to the velocity calculation of h i layer according to the method of step 3, and when all sedimentary unit-level layers are h iThe velocities of the layers are all calculated, and then the velocity field V3 to be established finally is obtained. Figure 4

[0133] The preferred embodiments of the present application are described in detail above, but the present application is not limited to the specific details of the above-described embodiments. Within the technical concept of the present application, various simple modifications can be made to the technical solutions of the present application, and these simple modifications all belong to the protection scope of the present application.

[0134] In addition, it should be noted that each specific technical feature described in the above specific embodiments can be combined in any appropriate manner without contradiction. In order to avoid unnecessary repetition, the present application will not further describe various possible combinations.

[0135] In addition, various different embodiments of the present application can also be combined in any manner, as long as they do not deviate from the idea of the present application, and they should also be considered as disclosed by the present application.​

Claims

1. A method for establishing a velocity field through stepwise matching of well-seismic horizons, characterized in that, Includes the following steps: Step 1: Prepare logging data, seismic data, and seismic horizon data (top and bottom of the target layer) for the target well location. 顶 and h 底 ; Step 2: Obtain the initial time-depth curve TD1 for each well by creating a seismic synthetic record; Step 3: Seismic horizon data h at the top and bottom of the target layer 顶 and h 底 Under trend constraints, the first velocity field V1 is established by interpolation of the initial time-depth curve TD1 of the well point; Step 4: Use the first velocity field V1 to separate the top and bottom layers of the target layer. 深顶、 top 深底 Transformation from depth domain to time domain top 时顶、 top 时底 ; Step 5: Under the constraint of the seismic horizon trend of the top and bottom of the target layer, perform top and bottom layering in the time domain. 时顶、 top 时底 Interpolation yields new top and bottom seismic horizons H. 顶1 and H 底1 , for H 顶1 and H 底1 Consistency analysis and outlier processing were performed separately to obtain the final seismic horizons H at the top and bottom surfaces. 顶 and H 底 ; Step 6: Utilize the depth domain to create a top and bottom layer. 深顶、 top 深底 The final top and bottom seismic horizons H obtained in step 5 顶 and H 底 The time-depth pair TD is obtained by matching the corresponding values. The time-depth pair TD is then used to correct the initial time-depth curve TD1 to obtain the corrected time-depth curve TD2 for each well. Step 7: At the final top and bottom seismic horizon H 顶 and H 底 Under trend constraints, the second velocity field V2 is established by interpolation using the corrected time-depth curve TD2; Step 8: Use the second velocity field V2 to stratify the depositional units within the target layer in the depth domain. 深1、 top 深2 ......top 深n Transform to the top of the time domain 时1、 top 时2 ......top 时n ; Step 9: At the final top and bottom seismic horizon H of the target layer. 顶 and H 底 Under trend constraints, the top layer of sedimentary units within the target layer in the time domain is stratified. 时1 top 时2 ......top 时n Interpolation yields seismic horizons H1, H2...H at the top of each sedimentary unit within the initial target layer. n For H1, H2...H n Consistency analysis and outlier processing were performed separately to obtain the final seismic horizon H of the top surface of each sedimentary unit within the target layer. d1 H d2 ......H dn ; Step 10: Utilize depth-domain depositional unit-level stratification within the target layer top 深1、 top 深2 ......top 深n The bottom layer of the target layer and the seismic horizon H of the top surface of each sedimentary unit within the final target layer obtained in step 9. d1 H d2 ......H dn H 底 The corresponding matching yields the final time-depth curve TD3 for each well; Step 11: Seismic horizon H at the top surface of each sedimentary unit within the final target layer. d1 H d2 ...... H dn H 底 Under trend constraints, the third velocity field V3 is established by interpolation of the final time-depth curve TD3.

2. The method according to claim 1, characterized in that, The data in step 1 were obtained through conventional well logging interpretation and seismic tectonic interpretation.

3. The method according to claim 1, characterized in that, Step 2 includes: calculating the reflection coefficient from the acoustic and density logging curves; convolving the reflection coefficient with the extracted seismic wavelet to obtain the initial synthetic seismic record; matching and adjusting the initial synthetic seismic record with the well-side seismic trace to obtain the final synthetic seismic record; each depth point on the final synthetic seismic record corresponds to a time value, thus obtaining the initial time-depth curve TD1 for each well.

4. The method according to claim 1, characterized in that, Step 3 includes: dividing the target layer into n smaller layers in the time domain according to equal proportions, with each smaller layer having a thickness of d, then: d=(h 底 -h 顶 ) / n Among them, h 底 and h 顶 These are the top and bottom seismic horizons of the target layer obtained from seismic tectonic interpretation, where n represents the number of sub-layers of the target layer; In h 顶 and h 底 We obtain n-1 seismic horizons, and calculate the seismic horizon h of each sub-layer. i : h i =h 顶 +i*d Where i represents the nth sub-layer, 1≤i≤n-1; Based on the initial time-depth curve TD1, each well in the time domain is correlated with the seismic horizon h. i The time-depth pairs at the intersection points are extracted and inter-well interpolation is performed to obtain the small layer h. i Planar velocity V i When n is large enough, h i Planar velocity V i It's h i The velocity of the layer is used to obtain the first velocity field V1 of the target layer.

5. The method according to claim 1, characterized in that, Step 4 includes: obtaining t = 2h / v from h = vt / 2, where t is the seismic double-layer travel time, h is the depth, and v is the velocity. Using the first velocity field V1, the top and bottom layers of the target layer are separated using the formula t = 2h / v. 深顶、 top 深底 Transformation from depth domain to time domain top 时顶、 top 时底 .

6. The method according to claim 1, characterized in that, Step 5 includes: using the two wells spaced at a predetermined distance as boundaries, interpolating to obtain new top and bottom seismic horizons H. 顶1 and H 底1 .

7. The method according to claim 6, characterized in that, When the distance between two wells is greater than the predetermined distance, the trend of inter-well layered interpolation is based on the seismic horizon trend; when the distance between two wells is less than the predetermined distance, the trend of inter-well layered interpolation is based on the time-domain layered interpolation trend of the two wells.

8. The method according to claim 6, characterized in that, In step 5, H 顶1 and H 底1 Consistency analysis and outlier handling were performed separately. When the time-domain stratification of an individual well differed significantly from that of nearby wells, resulting in anomalous bulges or depressions on the newly interpolated seismic horizons, and the well location did not align with the seismic horizon trend, outlier removal or smoothing was applied to that well location to obtain the final top and bottom seismic horizons H. 顶 and H 底 .

9. The method according to claim 1, characterized in that, Step 6 includes: using the top surface of the oil-bearing formation at the depth domain well point to stratify the formation and the final top surface seismic horizon H. 顶 Matching was performed using the bottom layer of the oil layer group and the final bottom seismic horizon H. 底 Matching is performed to obtain the time-depth pair (TD) at the top and bottom interfaces. The initial time-depth curve (TD1) is then corrected using the time-depth pair (TD) to obtain the corrected time-depth curve (TD2) for each well.

10. The method according to claim 1, characterized in that, Step 7 includes: dividing the target layer into n' smaller layers in the time domain according to equal proportions, with each smaller layer having a thickness of d', then: d’=(H 底 -H 顶 ) / n’ Among them, H 底 and H 顶 These are the final top and bottom seismic horizons obtained in step 5, where n' represents the number of sub-layers. In H 顶 and H 底 We obtain n'-1 seismic horizons, and calculate the seismic horizon H of each sub-layer. i : H i =H 顶 +i’*d’ Where i' represents the nth sub-layer, 1≤i'≤n'-1; Based on the corrected time-depth curve TD2, each well in the time domain is compared with the seismic horizon H. i The time-depth pairs at the intersection points are extracted and inter-well interpolation is performed to obtain the small layer H. i Planar velocity V i When n' is large enough, H i Planar velocity V i 'That is H' i The velocity of the layer is used to obtain the second velocity field V2 of the target layer.

11. The method according to claim 1, characterized in that, Step 8 includes: obtaining t=2h / v from h=vt / 2, where t is the seismic double-layer travel time, h is the depth, and v is the velocity. Using the second velocity field V2 and the formula t=2h / v, the top and bottom layers of each sedimentary unit are transformed from the depth domain to the time domain.

12. The method according to claim 1, characterized in that, Step 9 includes: using two wells spaced at a second predetermined distance as boundaries, and performing top-level stratification of sedimentary units within the target layer in the time domain. 时1 top 时2 ......top 时n Interpolation yields seismic horizons H1, H2...H at the top of each sedimentary unit within the initial target layer. n .

13. The method according to claim 12, characterized in that, When the distance between two wells is greater than the second predetermined distance, the trend of inter-well layered interpolation is based on the seismic horizon trend; when the distance between two wells is less than the second predetermined distance, the trend of inter-well layered interpolation is based on the time-domain layered interpolation trend of the two wells.

14. The method according to claim 12, characterized in that, In step 9, H1, H2...H n Consistency analysis and outlier handling were performed separately. When the temporal stratification of an individual well differed significantly from that of nearby wells, resulting in anomalous bulges or depressions on the newly interpolated seismic horizon, and the well location did not align with the seismic horizon trend, outlier removal or smoothing was applied to that well location to obtain the final seismic horizon H at the top surface of each sedimentary unit within the target layer. d1 H d2 ......H dn .

15. The method according to claim 1, characterized in that, Step 10 includes: using the sedimentary unit level stratification at the depth domain well point within the target layer. 深1 Seismic horizon H above the top of the sedimentary unit d1 Matching, hierarchical top 深2 With earthquake horizon H d2 Matching...layer top 深n With earthquake horizon H dn Matching, target layer bottom layering and H 底 Matching yields n+1 sets of time-depth pairs. These n+1 sets of time-depth pairs are used to correct the corrected time-depth curve TD2 to obtain the final time-depth curve TD3 for each well.

16. The method according to claim 1, characterized in that, Step 11 includes: applying the final time-depth curve TD3 to calculate the velocity of each layer in each sedimentary unit-level segment according to the method in Step 3. When the velocities of all layers in all sedimentary unit-level segments have been calculated, the final third velocity field V3 to be established is obtained.

17. The method according to claim 1, characterized in that, In step 10, the top of the oil layer group and the top of the first deposition unit are in the same layer.

18. The method according to claim 1, characterized in that, In steps 3 and 5, the number of sub-layers is determined based on the target layer thickness and the required accuracy of the speed to be established.

19. A computer-readable storage medium storing a computer program, characterized in that, When the computer program is executed by a processor, it performs the steps of the method as described in any one of claims 1-18.

20. A computer device, comprising: At least one processor; as well as A memory storing a computer program executable on the processor, characterized in that the processor executes the program to perform the steps of the method as described in any one of claims 1-18.

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