Study On The Methods Of Measurement And Profile Establishment Of Ground Stress

The state of ground stress field is one of the important and basic data for oil and gas exploration and development and for design of well drilling engineering. In this paper, the methods for ground stress measurement and profile establishment are researched. On the basis of the character of anisotropic of wave velocity and method of differential strain analysis (DSA), a new method named principal direction differential strain analysis has been developed to make the test simple. Relatively, the method has dramatically decreased difficulty when measuring and met the demand for degree of accuracy. At the same time, the mechanical model of fault has been studied to introduce the finite element method (FEM) to be used on discontinuity medium like rock. Also, a new method called constrained optimization finite element method, short for COFEM, has been generalized based on the theory of optimization and the FEM method, which has increased the accuracy degree and efficiency of the simulation work. Take block A of Daqing oil field as an example, the present ground stress field of which is simulated by the COFEM method .And the distribution of magnitude and orientation of the horizontal principal stresses have been obtained. The results have revealed that faults have an important influence on the ground stress field around them, and the general rule is summarized in the paper. In the end , using block A as an example, the application of ground stress in oil and gas development has been discussed from the aspects of fracture distribution forecast, prevention of casing damage, modification plan of hydro-fracturing and the disposition of water wells.