A Prediction Method for Unconventional Tight Reservoirs under Strong Reflection Background

A technology for reservoir prediction and compaction, which is applied in the field of petroleum geophysical exploration, can solve the problem of indistinguishable thickness of sand bodies, and achieve the effect of improving the prediction coincidence rate

Active Publication Date: 2017-12-05
PETROCHINA CO LTD
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Problems solved by technology

Therefore, the trough characteristics appear on the time-domain seismic section, and the long The thickness of the sand body cannot be distinguished

Method used

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  • A Prediction Method for Unconventional Tight Reservoirs under Strong Reflection Background
  • A Prediction Method for Unconventional Tight Reservoirs under Strong Reflection Background

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Embodiment 1

[0021] This embodiment provides a method for predicting unconventional tight reservoirs under a strong reflection background, which is characterized in that it includes the following steps:

[0022] (1) Through forward modeling, establish the different frequency characteristics corresponding to sand bodies with different thicknesses in the target layer, and establish a forward modeling model library;

[0023] The forward modeling in step (1) is realized in the following way: multiple wells are selected for GS time-frequency transformation analysis, and the thicknesses of the target layers corresponding to these selected wells are different.

[0024] The wells selected in the forward modeling process include three types. The target layer sand bodies of type I wells are characterized by thick layers and massive layers, the target layer sand bodies of type II wells are characterized by thick layers and massive layers + thin interbeds, and the target layer sand bodies of type III w...

Embodiment 2

[0031] Such as figure 1 Shown is the length of well X1 An example of tight reservoir prediction, this embodiment will be combined with the specific implementation effect to illustrate, using GS transform time-frequency analysis technology, can better identify long Section 8m above the tight reservoir. Using the unconventional tight reservoir prediction method under the strong reflection background of the present invention, the Ordos Basin The tight reservoir prediction coincidence rate reaches 76.6%, which plays an important role in tight oil well location deployment and horizontal well area selection.

[0032] figure 1 In the figure, x1 well length The main frequency of the segment advantage is 35-45Hz, and the 35Hz single frequency profile is long Obvious response, long pre-drill forecast The thickness of the tight sand body is 10m, and the actual drilling is 9.2m. The seismic prediction is in good agreement with the actual drilling.

Embodiment 3

[0034] When using time-frequency analysis to predict unconventional tight reservoirs, according to the specific geological characteristics of different regions, through seismic forward modeling and combined with actual seismic data, the relationship between different sand body thicknesses and seismic spectrum should be determined.

[0035] figure 2 It is a comparative analysis chart of the seismic forward modeling section spectrum of 3 wells in the West 233 well area. It can be seen from the figure that the length of the X2 well is The thickness of the tight sand body in this section is 25.7m, the sand body is integrated, and the middle length of the forward modeling section is The dominant frequency of the section is 25-45Hz; x3 well site The tight sand body in this section is 12.3m thick, and there are massive sand bodies and thin interbeds in the forward modeling section. The dominant frequency of the section is 25-55Hz; x4 well length The sand body is not develope...

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Abstract

The invention belongs to the technical field of petroleum geophysical exploration and particularly relates to an unconventional tight reservoir stratum forecasting method under a strong reflection background. Through forward modeling, different frequency characteristics corresponding to sand bodies with different thicknesses of a target layer are established, and a forward modeling model library is established. The seismic data of the target layer is subjected to time-frequency analysis, and the frequency domain data of the target layer is obtained. By using the frequency domain data obtained in the above step, through comparing the forward modeling model, the thickness of the target layer sand body is determined, by using the above steps, the seismic data and the model library are compared to obtain final reservoir stratum analysis condition, by using the GS transform time-frequency analysis technology, a long 7(2) section 8m above tight reservoir stratum can be identified well, the predication coincidence of the tight reservoir stratum is raised to 76.6%, and the method plays an important role in tight oil well position deployment and horizontal well area optimization.

Description

technical field [0001] The invention belongs to the technical field of petroleum geophysical exploration, and in particular relates to an unconventional tight reservoir prediction method under the background of strong reflection. Background technique [0002] Coal seams and source rocks developed in the underground formations, which have a large impedance difference from the surrounding rocks, form strong reflections on the seismic profile. The adjacent reservoirs are affected by the strong reflections, and the seismic response is weak, making prediction difficult. Predecessors tried to eliminate strong reflections or increase frequency in seismic data processing, but the results were not satisfactory. [0003] For example, the tight oil in the Ordos Basin is mainly developed in the Chang 7 oil layer group of the Triassic Yanchang Formation, especially the Chang 7 The tight reservoir is close to the source rock, and the reflection at the top of the reservoir is affected by...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): G01V1/30
Inventor 王大兴杨华赵玉华张杰赵德勇黄黎刚朱军
Owner PETROCHINA CO LTD
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