Study On The Evolution Of Fluid Dynamic And The Evolution History Of Fluid In Kuqa Depression

Kuqa Depression which the northern border was faults before the southern margin of Tianshan mountain and the southern border was the northern uplift in Tarim basin was located in the north of Tarim basin and extended in direction of NEE. The length in direction of WE was about 650 km and the width in the direction of NS was about 50 to 60 km, the area was 3.12×104 km2.Before the characteristics of fluid migration and accumulation being studied, evolution history of fluid dynamic must be restored first of all, because of being as specific history events set in geologically history periods. At the same time, It is important to analysis the evolution history of fluid for studying the fluid formation causation,the direction of migration and accumulation. The fluid migration and the evolution history of fluid have been important contents in basin analysis and petroleum exploration.Based on measured fluid pressure, the distribution of abnormal pressure is studied in actual Kuqa Depression. Based on the study of mudstone compaction, the law of mudstone compaction and calculated old fluid pressure in the most buried depth of stratum is summarized, the characteristics of excessive pressure both in vertical and horizontal distribution are discussed according to the fluid pressure calculated.During the research, a large of quantity of information geology, well logging and earthquake has been well used .Based on the comprehensive study, the mathematical model which fits to Kuqa Depression has been set up. The out-line of fluid dynamic evolution could be obtained by means of integrating methods of compaction curves analysis, basin numeried modeling and fluid enclosure determining.Based on the result of numerical simulation, mono-well excessive pressure evolution is distributed two stages by time: Jidike to The final stage of Kuqa is excessive pressure increasing stage, The final stage of Kuqa to now is excessive pressure increasing and disappearing stage; Abnormal pressure of Bashijiqike which belongs to the lower Cretaceous evolution is distributed two stages :The final stage of Jidike to The final stage of Kuqa, The final stage of Kuqa to now; the fluid dynamic evolution( gas potential) of the lower Cretaceous is distributed obviously two stages: The final stage of Jidike to the final stage of Kangcun, The final stage of Kuqa to now; The middle Jurassic fluid dynamic evolution(gas potential) is distributed two stages: The final stage of bashijiqike to the final stage of Kangcun, a The final stage of Kuqa to now.The migration and accumulation of hydrocarbon in main reservoirs from Kuqa Depression and the northern uplift in Tarim basin may be study by way of the theory of fluid potential, it is suggested that the seal or party seal area of relatively low potential of gas best benefits hydrocarbon accumulation, nature gases migration and accumulation systems of aim formations are distributed and which distribution and evolution is studied. Migration and accumulation systems are Kela2 well to R5 well, Baicheng to Tielieke, Yakexi to Yisidana and Kezier to Xinhe.At the same time, associated transport system distribution, nature gases migration and accumulation is analyzed.The primary components of the crude oil of Kuqa Depression are gas distillate and light crude .From Kelasu structural belt to the northern uplift in Tarim basin, nature gases are dry gases,damp gases and condensate.CH4 is the most ingredient in nature gases, the content of non-hydrocarbon is low. By studying fluid enclosure, ingredient temperature and pressure is evoluted when fluid enclosure had being formed.By the distribution of the formation water salinity, the ratio of Na+ and Cl~ (rNa+/rCl-) and coefficient of desulphuration (rS042-x100/rCl-), deoxidization of the northern uplift in Tarim basin, Dabeu Dawanqi and Quele areas is better than Yinan areas, it is good to oil and gas migration and accumulation.The hydrocarbon of Kuqa Depression has two evolution stages: Jidike to Kangcun is mainly oil forming time, Kuqa to now is mainly nature ga...