Study On Marine Oil And Seal Up For Safekeeping System In The Middle Yangtze Region

According to the theory of basin fluid chemistry-kinetics ,oil and gas compart ment, the main line of structural evolution and thermal evlution of source rocks,holding the principle of studying macro and micro,surface geology and subsurface geological and static and dynamic,the concept of oil and gas preservation system by the cover - the source of control, we analyze the appearance of oil and gas preservation system, causes, effectiveness and evaluate the preservation conditions of Marine oil and gas on the Yangtze Region .The author, based on field survey and testing and drilling, logging, and geophysical data,establish feature of caprock skeleton profile in the Middle Yangtze Region.The study area developed cover of muddy rocks and gypsum-salt rock, existed Cambrian, Middle Cambrian, Silurian, Middle Triassic - Jurassic, Cretaceous - Paleogene other five sets of regional seal and Lower Triassic Jialingjiang other five sets of local seal. Combined with distribution of the fluid surface,the overlying water chemistry,water chemistry correspondence analysis, and the relative energy independence between the cover closure and the fluid, revealed the oil and gas preservation system from T₂-J→S→∈₂→∈₁, covering an area of gradually increasing and was a "tower" the stacking structure.Based on the study in the tectonic evolution, it made the research on the cause of reform of oil and gas preservation system's "bit, body." Analyzing the major cover tectonic stages of the evolution of the chemical characteristics and the fluid - dynamic response characteristics of the Caledonian, Hercynian - Indosinian early Yanshan period, late Yanshan– Himalayan,it thought that development of depositional systems that cover the domain , diagenetic metamorphic cover, cover deformation deflection strength of the fault, "Three" coupling, the fluid reservoir were the dominant factors of the oil and gas preservation system. In which H-transgressive systems tract, HST were conducive to the formation of muddy rock, rock salt, gypsum cap rock class quality; the Cambrian, the Silurian cap have the advantage of moderate diagenetic metamorphism; Lower Cambrian weapons systems, in the Cambrian cover has a deformation strength of the small deflection characteristics ;The fault from Jianghan North East Xiangfan - wide economic, Jingshan - wulongquan fracture of West Hubei and East West Qi Yue Mountain, whose formation time from early to late, activity intensity from strong to weak, the "triple" configuration relations of the fault obeys the trend of changing from non-coupled to the coupled; Western Hubei and East of the Sinian - Triassic lack of heterologous fluid, the fluid reservoir is of good quality ; the region far away from the fault is under the fluid filling of the Early Paleozoic with different sources ,the fluid reservoir is poor, but in the late fluid filling, the Early Paleozoic and Mesozoic strata in the fluid are not mutually connected, the fluid reservoir is relatively good .On the basis of the study of the Hydrocarbon source rocks, the effective research on the evolution of the oil and gas preservation system "quality, quantity,". The important reform period of oil and gas preservation system is from Indo-China, for∈₁,∈₂ oil and gas preservation system, the late Indo-China - Early Yanshan hydrocarbon kitchen cracked from the kerogen to oil-cracking type transformation process, storage conditions continue; for S, T₂-J oil and gas preservation system, the early Yanshan source kitchen, still a cracking of kerogen type, but the strength of a larger transformation by tectonic activity, preservation conditions are weakened..Advantages and disadvantages of oil and gas preservation system of vertical differentiation of the sequence is:∈₂→S→∈₁→T₂→J system; horizontal sequence is Shizhu, Lichuan, Sangzhi , Huaguoping, Yichang, Mianyang, Dangyang system.Typical oil and gas compartment has a "build - transformation - fixed" dynamic characteristics, importantly analyzes a Cili Nanshanping Sinian, Paizhou Lower Cambrian, Jiannan Silurian, longjuba Permian oil and gas compartment. Summarized in the study area hydrocarbon preservation include continuous - the ultimate host,intermittent - take over the host,survival - the transition host,thrust - (?) Host four modes.Especially the ultimate host type, multiple sets of cover overlay, the same as the source of fluid filling the ideal model for hydrocarbon preservation, Jianshen no.1 well Silurian gas reservoirs as one typical type, the episodic closure / open cycle type closure mechanism of interpretation of the Silurian reservoir Hanjiadian , Xiaoheba , Longmaxi unique layers of gas, the gas reservoir of the closed primarily originated in the abnormal high pressure, and high-pressure sealing ability is the film closed 7 times as many as amended in the past that the "deeply buried marine cover,highly diagenetic metamorphic and poorly closed performance," the general point of view.Based on the appearance,causes and effectiveness studies of oil and gas preservation system, the author established the structure - deposited polycyclic superimposed, multiple structural transformation in the Yangtze region oil and gas preservation system evaluation system. Based on the appearance of oil and gas preservation system, causes, effectiveness studies, the establishment of the structure - deposited polycyclic superimposed, multiple structural transformation in the Yangtze region oil and gas preservation system evaluation system.