An optimization method for fracturing horizontal wells in tight oil reservoirs based on an adaptive surrogate model

Abstract

The invention discloses a dense oil reservoir fracturing horizontal well optimization method based on a self-adaptive agent model. The method includes the following steps that S1, an optimization parameter x is determined, a target function J(x) is established, and an initial design space D is determined; S2, an initialization parameter k is 1, a sample X0 is obtained in the space D, and sample data X0 is processed to obtain a sample; S3, the variable X0 is substituted into an oil reservoir numerical simulator, an initial variable objective function value J(X0) is obtained, (X0,J(X0)) is stored in a sample point database, and according to the corresponding relationship between X0 and J(X0), a kth gaussian process agent model is established; S4, the self-adaptive process of the kth gaussianprocess agent model is carried out through point addition and an important design space; S5, iteration is stopped when a convergence criterion is satisfied, and otherwise step 6 is executed; S6, k isequal to k+1, the important design space and the sample point database are updated, and then step 4 is repeated. The integrated optimization design of horizontal well spacing and fracturing is adopted, so that accurate optimal well spacing and fracturing parameters are obtained, and the method has great significance on the development of dense oil reservoirs.

Description

technical field [0001] The invention relates to the exploration and development of tight oil and gas reservoirs, in particular to an optimization method for fracturing horizontal wells in tight oil reservoirs based on an adaptive proxy model. Background technique [0002] Tight oil and gas reservoirs are another new hotspot in global unconventional oil and gas exploration and development after shale gas reservoirs. Fracturing horizontal wells has become the most important technical means in the development of low permeability reservoirs. The development investment of fractured horizontal wells is expensive, and improper well location selection will make it difficult to meet the development efficiency of the reservoir and achieve corresponding economic benefits. At the same time, in the total development cost of tight oil reservoirs, drilling cost and fracturing cost account for a large proportion. Therefore, when designing horizontal well location and well type with economic...

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Problems solved by technology

[0004] At present, with a coarser reservoir model, it is possible to use a coarser gridded reservoir numerical simulation to predict the development effect in the optimization process. Compared with a finer reservoir numerical model, although the calculation accuracy is reduced, the cost of a single simulation However, it is difficult to optimize the fracture parameters of the fractured horizontal well in this way; the optimization of the well layout and injection-production parameters can be realized by separately optimizing the well layout parameters of the fractured horizontal well and the fracturing parameters. When fracturing the optimal fracture parameters for horizontal wells, multiple sets of plans for fracturing horizontal wells were formed by further combining the geological characteristics of the reservoir, the combination of fracture lengths at different locations, and the combination of fracture conductivity. The integrated optimization design technology of horizontal well layout and fracturing, the solution obtained is often suboptimal

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