The Development Of Fluid Pressure And The Relationship Between Pressure Development And Pool Forming Process In West Sichuan Basin

There is broad and high abnormal fluid pressure in western SiChuan Basin. It is indispensable that the investigation of mainly causes of abnormal pressure and relationship between pressure development and pool forming process. It is essential to research that how the pressure came into being and what did it influence on the pool in the period of geo-history, not just only the study of cause and their relation nowadays.On the basis of measure data in the formation of SiChuan Basin, the development of pressure is restored by means of basin simulation, with the scale on the study of compaction and calculation of engender pressure of fluid inclusion. It is been analyzed that the relation between the development of fluid pressure and basic elements of reservoirs, such as history of hydrocarbon-production, generation and distribution of fault and fracture and so on. Finally, three type of reservoirs model are established.The main conclusions below can be drawn,Nowadays, the center of fluid pressure in western SiChuan Basin is located the Depression of ZiTong, in where the coefficient of pressure is above 2.2. Above the Xu-Jia-He Formation (Upper Triassic), the section of pressure could be dived into three portions, which are named after normal pressure portion, high pressure portion and super-high pressure portion. The range of coefficient of pressure is from 1.0 to 2.2 in the section.There is quite difference matter, which have made the abnormal fluid-pressure, in different region and era. The disequilibrium compaction and the generation of hydrocarbon are the mainly reasons that have caused the overpressure before Paleogene Period. From Neogene to nowadays, the tectonic compression becomes chiefly matter that caused the fluid-pressure accumulation again. So the development of abnormal pressure in western SiChuan Basin came through two epochs, namely the epoch of deposit overpressure(J2-E), and the epoch of tectonic overpressure(N-R).From Jap to KI, the deposit overpressure is the most prosperous in northwestern SiChuan Basin. In different circumstance, it exist two peaks, during the development of deposit overpressure in southwestern region. The early one is from Jap to KI, the later is from K2 to E. And then, the fluid pressure was becoming diminishing. Controlled by sediment, the center of deposit overpressure is chiefly located the Southwestern SiChuan Basin, and the tectonic overpressure's located in the Depression of ZiTong in northwestern. On the position of faults and fractures, fluid pressure fell down to the hydrostatic pressure nearly.There is closing relationship between overpressure and pool forming process. As the mainly driver effect of fluid movement, overpressure provide enough dynamical during the course of pool forming. The overpressure offered the effective dynamical to movement to the oil and gas when it is leaked. So the relation between overpressure and transportation system of hydrocarbon, such as fault and fracture, was affinity during the process of migration of oil and gas. The hydrocarbon below the overpressureformation also could be sealed by fluid pressure. Integration the development of fluid pressure and characteristic of basic elements of reservoirs, three typical model of reservoir are established, ie. high pressure and near source rock reservoir, high pressure and multi-layer reservoir and super-high pressure and near source rock reservoir.SUN Mingliang (Earth survey and information technology)Directed by WANG Zhenliang...