A PRELIMINARY STUDY ON THE FORMATION MECHANISMS OF NATURAL FRACTURES IN RESERVOIRS:AN EXAMPLE FROM JINGBEI BURIED-HILL POOL, NORTH OF CENTRAL LIAONING PROVINCE

There are a variety of formation mechanisms for the natural fractures in reservoirs.The fracture distributions produced by different mechanisms are not the same.It is usual that fractures on the whole are formed by many kinds of mechanisms in the same period or in different periods.In this paper,a new train of thought is suggested about evaluation on the formation mechanisms of fractures.Based on geological analyses,various possible formation mechanisms of dominant fractures are put forward,and a ling-typed fracture distribution model to predict initial production first-order approximately is established.Then,the sdution of the model is found according to related production data,and the information used in the evaluation of each mechanism is obaained.The application in Jingbei buried-hill fracture pool reveals that unloading and fault activities are two major formation mechanisms of reservoir fractures in this pool,the formed fractures show relatively even distribution in related range and close,wide and irregular features of fractures are directly related to the strong faulting of mang stages and directions.