Analysis Of In-situ Stress And Fracture Prediction Research Based On Acoustic Logging Data

Reservoir stress suggests a direct control effect of oil and gas formation and movement, and the fracture is the major seepage channel of oil and gas. So,study on in-situ stress character and fracture development of reservoir has a very important guidance meaning to the engineering.The in-situ stress and crack development characteristics of oilfield reservoir based on acoustic logging data are studied in this paper, and the major contents are summarized as follows:Firstly, this paper analyses the calculation methods of in-situ stress distribution, and the main methods include acoustic logging, hydraulic fracturing and finite element simulation. The methods can be considered as theoretical basis for analysis of in-situ stress.Secondly, the methods of sonic logging and hydraulic fracturing are employed to calculate the principal stress in a certain studied block. Then, with the size and orientation of in-situ stress in typical well as constraint target, finite element numerical simulation was performed to research the distribution of in-situ stress in the block, and the law of in-situ stress distribution was found. The results of in-situ stress obtained from the three methods were also compared in this paper.Thirdly, based on the results of in-situ stress in the block, finite element method was applied to obtain the feature of fracture development on reservoir plane. According to the criteria of rock rupture, fracture development graph and contour map of breaking rate were drawn in the block.Fourthly, the formation mechanical properties have close relationship with development law of cracks in oilfield reservoir as well as the distribution of in-situ stress. The compressional and shear waves in a formation were extracted based on acoustic logging information, and application software of acoustic logging was compiled by combining with density data and related calculation criterion.Finally, the relationship between hydraulic fracturing crack and in-situ stress was analyzed, and the effect law of relative in-situ stress on fracture morphology was getted.The paper also studied the relationship between reasonable well network and well spacing density, then, the optimization matching relationship between well pattern and in-situ stress was obtained. Baesd on the law of above mentioned, the orientation of hydraulic fracturing and deployment of well pattern and spacing were determined.