The Formation Pressure Characteristics And Its Hydrocarbon Accumulation Mechanism In The Upper Fourth Member Of Shahejie Formation In The Boxing Area

The research object of this paper is beach-bar sandstones of the upper Es4in BoxingArea.It analysis the abnormal pressure and distribution characteristics in the study areaand establishes the pressure boost method. Based on the analysis of reservoirs dynamiccharacteristics of the study area,the paper discusses the control function between oil andpressure field.According to the measured formation pressure data, analysising the distributioncharacteristics of the present pressure fields, the abnormal pressure of the region performsa trend-“normal pressure-the transition pressure-overpressure–transition pressure-normalpressure.” It can be divided into normal-pressure system, the transition pressure system,and overpressure system. The main causes of the abnormal pressure contain lowcompaction and hydrocarbon-generation. The formation mechanism of abnormal pressureis different at the stages of basin evolution. The early stage of basin development, thedeposition rate is slow and developing normal pressure. With the acceleration of thesedimentation rate, pore water can not be removed immediately and result overpressure.Asthe further depth, the hydrocarbon began to be produced and the the pore fluid expanded todevelop the abnormal pressure. Abnormal pressure control the reservoir. The properties ofoil, the nature of the formation water and the fullness change as the change of abnormalpressure. Based on the controlling of the reservoir characteristics, the paper summed up thereservoir characteristics of the different pressure systems: he overpressure is dominated bylitheologic reservoir, fullness is higher. The structural-lithologic reservoir is the most in thetransition pressure, however, in the normal pressure the structural reservoir is the most, andoil layer located above the water layer. Based on the above analysis, he paper establishesthe pool-forming pattern which is controlled by abnormal pressure of the upper Es4inBoxing Area.