The long-term development of hydrocarbon reservoirs (HCR) in the geological environment, complex deformation processes occur. Gravity monitoring is carried out to evaluate the possible geodynamic risk and negative consequences from HCR. As a result, the interrelationships of the continuously changing field-geological situation (changes in production volumes, changes in reservoir pressure, processes of fluid injection into productive formations) are investigated. The main tool for solving the gravity inversion when determining areas of increased industrial hazard is the solution of the gravity direct problem. In these studies, proceeding from a given initial approximation of the environment, the problem is realized through successive approximations. To assess such distributions, the authors of the article recommend using the simulated annealing technique within the framework of stochastic optimization. It is aimed at fitting the optimal parameters of the medium provided that a minimal residual of the gravity field values occurs. The approach is implemented using three simple mathematical models of the geological medium such as horizontal prism, homogeneous sphere, and vertical ledge. This technique allows fitting the media values simultaneously by a pair of its parameters. The operation of the algorithm is described and the simulation results are provided. The results showed acceptable accuracy of the algorithm for solving the direct gravity problem by the proposed method. The simulated annealing technique made it possible to increase the reliability of the HCR model while reduce the time for the analysis of the gravity field.
Optimal approaches to solving many problems are required in many areas. One of these areas is the determination of the occurrence of gravity anomalies in oil and gas fields. In this paper is proposed a new approach for determining the source of gravity anomalies in an oil and gas fields by estimating the gravity parameters associated with simple-shaped bodies such as a homogeneous sphere, a horizontal prism, and a vertical step. The approach was implemented in the computational module of the GeoM information system for optimizing the solution of a series of direct gravimetry problems using a genetic algorithm (GA). Approach is based on solving the direct gravimetry problem to minimize the discrepancy of gravity variations by the genetic algorithm. The method allows to select values simultaneously for several parameters of the studied environment. The task is realized through successive approximations based on a given initial approximation of the medium.
The paper indicates the initial calculation parameters and criteria for finding optimal solutions for models of the geological environment. The calculations were carried out for such models of the environment as a homogeneous sphere, a horizontal prism and a vertical ledge. For calculations, the results of gravimetric monitoring at one of the Kazakh oil and gas fields were used. The paper demonstrates the operation of the algorithm and presents the results of modeling for three available field profiles. The obtained results of the system showed an acceptable accuracy of the algorithm up to 10-11. The genetic algorithm made it possible to significantly increase the reliability of the model and reduce the working time for analyzing the measured gravitational field
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