The Study And Application Of Ground Stress Characteristics In Area X3

Ground stress is one of the important data for oil and gas resource assessment, reservoir simulation and engineering design of oil and gas wells, and moreover, complete and precise information about ground stress is a fundamental guarantee of the reliability and accuracy for production engineering design.This paper investigated the 3D distribution of ground stress in area X3 by jointly using laboratory experimental study and finite-element numerical simulation. For the first, palaeomagnetic direction-finding technique was adopted to determine the orientation of the core samples. To ensure the precision of measurements, simplify the experimental operation and raise the ratio of success, both methods of differential strain analysis and nonisotropic diagnosis of wave velocity were applied to measure the ground stress. These two methods were used in combination, they verify their results each other, and as a result, the magnitude and direction of the ground stress was settled correctly at every location where core was sampled. For the second, the dynamic and static parameters of formation were measured simultaneously through laboratory experiments. The relationship between them was established, which makes the transform between them possible, from dynamic to static or from static to dynamic.With the achievement of well log interpretation incorporated as another information, the vertical distribution of mechanic parameters of formation was defined, which offers a basis for the subsequent numerical simulation of 3D ground stress field. For the third, finite-element numerical simulation was done to calculate the 3D distribution of ground stress by inversion method. This overcomes the limitation of ground stress measurement, which can only supply one or several points, not the whole body of the formation. Numerical simulation also widened the extent of application of the result of stress measurement. It takes into consideration the mutual influence of different layers over each other and the structural factors such as the heterogeneity of formation thickness and the mode of occurrence of formation and fracture.The simulation presented us with the horizontal stress distribution across the upper interface and the lower interface of the main layer, the vertical distribution of ground stress across any longitudinal profile.As the last work, the research achievement about the characteristics of the ground stress in area X3 is employed to optimize the project design of perforation, fracturing and sand control. It contributes a very efficient technological approach for the triumphant development of the whole oilfield.