CN113514883A

CN113514883A - Fault-lithologic reservoir depicting method

Info

Publication number: CN113514883A
Application number: CN202110679718.8A
Authority: CN
Inventors: 李智; 王雪梅; 李锋; 李岩; 熊健; 王雷; 王黎明; 应森群; 黎腾; 安艳君; 张志业; 武子钰; 付江娜
Original assignee: China Petroleum and Chemical Corp; Exploration and Development Research Institute of Sinopec Henan Oilfield Branch Co
Current assignee: China Petroleum and Chemical Corp; Exploration and Development Research Institute of Sinopec Henan Oilfield Branch Co
Priority date: 2021-06-18
Filing date: 2021-06-18
Publication date: 2021-10-19
Anticipated expiration: 2041-06-18
Also published as: CN113514883B

Abstract

The invention belongs to the technical field of oil reservoir identification, and particularly relates to a fault-lithologic oil reservoir depicting method. In the process of carving the fault-lithologic oil reservoir, the invention fully utilizes various data, including well logging data and seismic data, and carries out human-machine interaction interpretation by combining well and seismic, thereby defining the structural characteristics, and carrying out reservoir analysis according to the thickness of a target layer sand body, a well logging phase and reservoir prediction, defining the reservoir distribution range, accurately evaluating the trap distribution range of the fault-lithologic oil reservoir, building the productivity in time, having practicability and timeliness, and providing a powerful means for fault-lithologic oil reservoir exploration and development.

Description

Fault-lithologic reservoir depicting method

Technical Field

The invention belongs to the technical field of oil reservoir identification, and particularly relates to a fault-lithologic oil reservoir depicting method.

Background

With the improvement of the exploration degree of the east fault trap basin in China, large-scale structural oil reservoirs which are easy to discover are mostly discovered, and exploration objects begin to transfer to low-order fault trap, lithologic trap and fault-lithologic trap. However, the difficulty of identifying the low-order fault is high, the sand body of the small-sized fracture basin changes rapidly, and the sand body is easy to migrate laterally, so that the difficulty of identifying the trap is increased year by year. In addition, in the face of the increasingly severe crude oil production situation of old oil fields, the precision of the trap drawing must be improved, and the construction capacity is accelerated.

The fault-lithologic trap belongs to a composite trap, has higher requirements on the structure and the configuration of sand bodies, has the characteristics of 'breaking', 'small', 'thin' and 'deep' in an oil reservoir, and is difficult to accurately depict. The term "fragmentation" refers to structural fragmentation, low-order fault development, and low degree of fragmentation and compaction; the small refers to that the range of the sand body of the river channel is small, the lateral swing is fast, and the range of the sand body is not easy to determine; "thin" means that the oil layer is thin and the number of superposed oil layers is often small; "deep" means that the oil is buried deeply and the development cost is high. Therefore, how to accurately depict the trap and realize quick production building is a problem to be solved. In the process of describing fault-lithologic reservoir trap, the prior art often adopts a single method to describe, for example, the single method is adopted to determine the sand body distribution range, which easily causes inaccurate description.

Disclosure of Invention

The invention provides a fault-lithologic reservoir delineation method which is used for solving the problem of inaccurate fault-lithologic reservoir delineation caused by the prior art.

In order to solve the technical problems, the technical scheme and the corresponding beneficial effects of the technical scheme are as follows:

the invention provides a fault-lithologic reservoir depicting method, which comprises the following steps:

1) selecting a typical well in a work area, making a synthetic seismic record by using logging information of the typical well and seismic wavelets corresponding to seismic channels beside the well, and performing horizon calibration on the work area according to the synthetic seismic record;

2) correcting the synthetic seismic record according to the regular survey lines in the seismic section until the seismic reflection horizon is closed in the whole area;

3) identifying faults and breakpoints by using the corrected synthetic seismic records to obtain a fracture system diagram of the work area;

4) establishing a logging velocity field and a seismic velocity field, obtaining a three-dimensional velocity field according to the established logging velocity field and the seismic velocity field, and obtaining a construction of a work area according to the three-dimensional velocity field;

5) determining a mark layer according to the logging curve so as to carry out stratum comparison and determine the thickness of a sand body of a target layer;

6) dividing an underwater diversion river channel and front edge mat-shaped sand according to the curve form of a logging curve so as to analyze a logging phase;

7) carrying out a desanding experiment on the oil and gas high-quality reservoir, and analyzing the amplitude change rate to predict the seismic reservoir;

8) making a sand thickness map according to the sand thickness of a target stratum, a logging phase and a predicted reservoir stratum, and determining an effective reservoir stratum range;

9) and (4) according to the determined fracture system diagram and the effective reservoir range, describing the fault-lithology reservoir.

The beneficial effects of the above technical scheme are: in the process of carving the fault-lithologic oil reservoir, the invention fully utilizes various data, including well logging data and seismic data, and carries out human-machine interaction interpretation by combining well and seismic, thereby defining the structural characteristics, and carrying out reservoir analysis according to the thickness of a target layer sand body, a well logging phase and reservoir prediction, defining the reservoir distribution range, accurately evaluating the trap distribution range of the fault-lithologic oil reservoir, building the productivity in time, having practicability and timeliness, and providing a powerful means for fault-lithologic oil reservoir exploration and development.

Further, in step 2), the regular survey lines include a main survey line, a tie line and any well connecting line.

Further, in step 3), the breakpoint is identified according to the dislocation, bifurcation, combination, distortion, shape and number mutation of the seismic event, and the dislocation of adjacent layers and the occurrence of abnormal wave.

Further, in the step 3), when the structure interpretation is carried out, the method also comprises the step of splitting the combined fault according to the fault distance.

Further, in order to accurately split the combined fault to obtain a real fracture system diagram according with geological rules, the basis for splitting the combined fault is as follows: the fault distance on the seismic section is consistent from top to bottom or from top to bottom along the same fault, and the fault distance on the plane is large in the middle and gradually reduced towards two sides along the trend.

Further, in the step 6), the underwater diversion river channel and the front edge matting-shaped sand are divided by adopting the following method: the natural potential and the natural gamma curve of the underwater shunt river channel are box-shaped or funnel-shaped, and the amplitude difference of the deep and shallow lateral resistivity curves is greater than a first set threshold; the natural potential and the natural gamma curve of the front edge matting-shaped sand are in a finger shape, the amplitude difference of the deep and shallow lateral resistivity curves is smaller than a second set threshold, and more than 2 tooth peaks are provided; the first set threshold is greater than the second set threshold.

Further, the first set threshold is 15 Ω · m, and the second set threshold is 10 Ω · m.

Drawings

FIG. 1 is a flow chart of a fault-lithology reservoir characterization method of the present invention;

FIG. 2 is a schematic view of the present invention of recombining faults in cross-section according to fault spacing;

FIG. 3 is a schematic diagram of the R-well region small layer top surface structure of the present invention;

FIG. 4 is a cross-sectional view of a fault seismic of the present invention;

FIG. 5 is a graph of a forward desanding experiment of the present invention;

FIG. 6 is a graph of attribute prediction for the present invention;

FIG. 7 is a plot of sand thickness and sedimentary microphases for the present invention;

FIG. 8 is a fault-lithologic trap range and well map of the present invention.

Detailed Description

The flow of the embodiment of the fault-lithologic reservoir characterization method of the invention is shown in figure 1 and is specifically described below.

Combining well and earthquake, and carrying out man-machine joint interpretation by using well logging data and earthquake data of well drilling to determine structural characteristics.

1. And extracting a reflection coefficient sequence by using acoustic logging data, extracting seismic wavelets from the corresponding reflection time periods of the well-side seismic channels, making a synthetic seismic record, and comparing the synthetic seismic record with the well-side seismic channels until the seismic geological horizon is basically uniform.

2. On the basis of horizon calibration, horizons are compared, closed, adjusted and verified on a seismic section through fine interpretation of main survey lines, tie lines and any well connecting lines, and synthetic seismic records are corrected in the process until all seismic reflection horizons are closed in the whole area.

3. The fault is explained by adopting technologies such as multiple attributes, multiple display modes, multiple explanation directions, encryption explanation and the like, and the fault is identified by using technologies such as coherent bodies, time slicing and the like. In the fault interpretation process, breakpoints are identified according to phenomena of dislocation, bifurcation, combination, distortion, shape and number mutation caused by the earthquake in-phase axis, dislocation of adjacent layers, appearance of abnormal waves and the like.

4. The combined fault is split according to the principle that the fault distances along the same fault on the section are consistent up and down or large and small down, the fault distances along the direction on the plane are large in the middle and gradually reduced towards two sides, the rationality of fault identification is guaranteed, and the fault distance recombination fault schematic diagram on the section is shown in figure 2. In the whole process, the interpretation result is continuously corrected by combining the drilling and encountering break points, so that a real fracture system diagram according with the geological rule is obtained, and the fault seismic profile diagram is shown in fig. 4.

5. A well-seismic constrained velocity model is adopted, a three-dimensional logging velocity field is established by utilizing VSP and seismic logging, then the seismic velocity field is established by utilizing three-dimensional data actually measured by a well hole, a high-precision three-dimensional velocity field is obtained by correction, and a real tectonic graph is obtained by variable-speed mapping.

The above steps are performed to obtain a structural diagram of the top surface of the R-well sub-layer, which is a monoclinic structure rising from south to north as shown in FIG. 3. 7 faults are developed in total, and the sections are combined into a Y shape and a step shape; the plane goes to the north east, and the two faults F4 and F5 intersect near the F-well.

And step two, performing reservoir analysis according to the sand thickness of the target layer, the logging phase and the predicted reservoir aspects, and determining the reservoir distribution range.

1. And determining a mark layer by applying a high-precision sequence stratigraphy principle and taking a gamma curve as a main part and a natural potential, sound wave, neutron and depth lateral curve as an auxiliary part, and carrying out stratum comparison. And reading the single-layer thickness, the effective thickness and the oil-containing property of the sand body of the target layer. The attribute prediction is shown in fig. 6.

2. And dividing the underwater flow-dividing river channel and the front edge mat-shaped sand according to the shape of the logging curve so as to analyze the sedimentary facies. The natural potential and the natural gamma curve of the underwater shunt riverway are box-shaped or funnel-shaped, and the amplitude difference of the deep and shallow lateral resistivity curves is more than 15 omega.m; the front edge matting sand natural potential and the natural gamma curve are in a finger shape, the amplitude difference of the deep and shallow lateral resistivity curves is less than 10 omega.m, and more than 2 tooth peaks are provided. The sand thickness and the sedimentary phase diagram are shown in fig. 7.

3. And carrying out reservoir seismic response quantitative analysis. Calculating the amplitude change rate of the two-dimensional forward sand removal experiment analysis, wherein the change rate is | (A)_{Rear end}-A_{Front side})/A_{Front side}I.times.100%), wherein A_{Front side}Amplitude before desanding, A_{Rear end}The results are shown in Table 1 for the amplitude after desanding and in FIG. 5 for the experimental chart, and it was found that the amplitude energy of the upper and lower three in-phase axes was changed after desanding. Wherein the amplitude of the upper peak becomes weaker, and the amplitudes of the middle trough and the lower peak become stronger; the amplitude change rate of the lower peak is maximum, and the upper peak and the trough are in order. Therefore, the reservoir spread range is comprehensively predicted by synthesizing envelope curves of the three same-phase axis reservoir spread ranges mainly based on the lower peak reservoir prediction, and the prediction multi-solution is reduced.

TABLE 1 Rwell zone reservoir seismic response rate of change table

Same phase shaft	Amplitude before desanding	Amplitude after desanding	Rate of change
				Upper wave crest	0.11	0.083	24.55
Trough of wave	-0.12	-0.14	16.67
				Lower wave crest	0.10	0.14	40

4. And (3) making a sand thickness map according to the sand thickness, the log facies and the seismic reservoir prediction, determining the sand boundary and the sand form, determining the effective sand range, and finally obtaining the fault-lithologic trap range and the well map as shown in figure 8.

And executing the steps of the method to finally obtain a small layer of river sand body of the R well area H34-1, wherein the small layer of river sand body is spread from north to south, and the small layer of river sand body is thinned to be sharp and extinguished towards two sides and the southeast part, and the small layer of river sand body can be divided into two micro-phases of an underwater diversion river channel and front edge mat-shaped sand.

The invention discloses a fault-lithologic reservoir depicting method, and aims to solve the problems that fault-lithologic trapping identification difficulty is high, well pattern deployment disorder and time lag are caused by the fact that a trapping process is implemented by means of drilling. The invention can accurately implement the structural characteristics and the sand body distribution, describe the fault-lithologic trap oil reservoir distribution and rapidly deploy the well position. At present, 7 wells including an oil reservoir evaluation well, an oil production well and a water injection well are deployed in an R well region, and at present, 2 wells are drilled, so that high-yield industrial oil flow is obtained.

Claims

1. A fault-lithologic reservoir characterization method is characterized by comprising the following steps:

9) and (4) according to the determined structure and the effective reservoir range, depicting the fault-lithology reservoir.

2. The fault-litho reservoir characterization method according to claim 1, wherein in step 2), the regular lines comprise a main line, a tie line and an arbitrary well connecting line.

3. The fault-lithology reservoir characterization method according to claim 1, wherein in step 3), the breakpoint is identified according to dislocation, bifurcation, combination, distortion, shape and number mutation of seismic event, and dislocation of adjacent horizons and occurrence of abnormal wave.

4. The fault-lithology reservoir characterization method according to claim 1, wherein in step 3), in the construction interpretation, the method further comprises the step of splitting the combined fault according to the fault distance.

5. The fault-lithology reservoir delineation method of claim 4, wherein the basis for splitting the combined fault is: the fault distance on the seismic section is consistent from top to bottom or from top to bottom along the same fault, and the fault distance on the plane is large in the middle and gradually reduced towards two sides along the trend.

6. The fault-lithology reservoir characterization method of claim 1, wherein in step 6), the underwater diversion channel and leading edge matting sand are divided by the following method: the natural potential and the natural gamma curve of the underwater shunt river channel are box-shaped or funnel-shaped, and the amplitude difference of the deep and shallow lateral resistivity curves is greater than a first set threshold; the natural potential and the natural gamma curve of the front edge matting-shaped sand are in a finger shape, the amplitude difference of the deep and shallow lateral resistivity curves is smaller than a second set threshold, and more than 2 tooth peaks are provided; the first set threshold is greater than the second set threshold.

7. The fault-litho reservoir delineation method of claim 6, wherein the first set threshold is 15 Ω -m and the second set threshold is 10 Ω -m.