The Research Of Sedimentary Characteristics And Diagenetic Environment In Permian Jiamuhe Formation Of Zhongguai Area In The Junggar Basin

This paper takes the tight reservoir in the second member of Jiamuhe formation in Zhongguai area in Junggar Basin for example.By using multidisciplinary theories and methods,The high resolution sequence stratigraphy framework in the second member of Jiamuhe formation was established;using dense sandstone multi-attribute prediction technology studied the sedimentary system and sedimentary model in the sequence framework; analysis nowadays to moderate pressure characteristics, different hydrocarbon filling periods of ancient to moderate pressure, acid and alkali diagenetic environment characteristics, the vertical change of clay mineral content and physical properties, diagenetic mode and the corrosion mechanism of zeolite and diagenetic evolution sequence, reveals the diagenetic ambient temperature, pressure and fluid properties changing with the time. Primary understanding and the research results are as follows:(1)Volcanic rock formation is layered output and can be horizontal contrast with normal sedimentary rock strata adjacent regions.Two sets of volcanic rock strata which are identified of the drilling information calibration on seismic section using seismic record,and they have a certain sequence stratigraphy boundary response,the comparative between the Wells are ideal.the second member of Jiamuhe formation is divided into 3 fourth-order sequences PSQ3-1、PSQ3-2 and PSQ3-3.(2) Clastic rock and normal event volcanic rocks coexist of the second member of Jiamuhe formation through core observation analysis,oxidation and grey mudstone also prove that there are two sedimentary water and underwater environment,coarse granularity, poorly sorted, edges and corners and edges and the characteristic of proximal is obvious determine the main for the fan delta deposits of the second member of Jiamuhe formation, volcanic rock formation mainly located at the base of the quaternary sequence, The thickness is small and doesn’t affect the normal clastic deposits.The plane fan delta plain area gradually decreases and show the phenomenon of retrogradation.(3)Describes the current formation temperature, geothermal gradient, formation pressure and pressure coefficient characteristics through the drilling test formation temperature, formation pressure and mudstone acoustic time study. By using the principle of heating gas movement intensified heating calcites in zeolite and inclusions,Observed more gas and liquid two phase inclusions, overcome the difficulty that gas and liquid two phase are difficult to find under the normal temperature, tested uniform temperature and freezing point of the brine inclusions, inferred there are two major periods of oil and gas filling in the second member of Jiamuhe formation using the uniform temperature, predicting paleogeothermal gradient of the typical Wells in different accumulation period,and completed thermal history of the typical Wells. Paleogeothermal gradient are larger than today’s geothermal gradient When the two phases of oil and gas filling, the thermal evolution of the second member of Jiamuhe formation is temperature increased in rapid burial stage, decreased in tectonic uplift stage, increased in early stage of then buried and later temperature decreased.(4)Freezing point was used to calculate the inclusion salinity, and calculated the formation pressure of each well of different hydrocarbon filling periods through the salinity-formula method, speculated the ancient buried depth of different hydrocarbon filling periods through paleogeothermal gradient, restored the pressure coefficient when the inclusions were captured, summarizes the change law of formation pressure of typical Wells Compared with current pressure coefficient, The process of formation pressure of the second member of Jiamuhe formation is increased in rapid burial stage, decreased in tectonic uplift and increased in buried again.(5)Summarizes characteristics of acidic and alkaline diagenetic environment in the reservoir, statistics vertical change of the clay mineral content、 porosity and permeability to analysis the changing rule of the vertical of acidic and alkaline diagenetic environment. Proposed a method which using uniform temperature judgment zeolite and calcite formation period and cause, combined with the burial history and zeolite dissolution mechanism that diagenetic evolution sequence, and the reservoir diagenetic evolution sequences was discussed, estimated the fluid properties evolution of the second member of Jiamuhe formation: alkaline diagenetic environment in early rapid burial stage; the upper reservoir acid is diagenetic environment and lower reservoir is mainly alkaline diagenetic environmen in tectonic uplift of atmospheric water leaching stage;and from basic to acidic to alkaline to acidic to alkaline in burial stage.