Study On Reservoir Characteristics Of Chang 6 And Chang 8 Reservoirs In Yancha Formation, Yierzhuang Area, Ordos Basin

Yeer Zhuang oildom is located in the midwest of Ordos basin, it has long exploration period, and has been into a stable stage. The study area’s main pay zone is Chang 6 and Chang 8 oil reservoir of Yanchang group, the change of single well production is bigger, and the output of adjacent wells also has a lot of difference. A preliminary study shows that the oil reservoir distribution is the main reason that cause the differences. This paper through to the Yeerzhuang’s of core, logging, testing and other data, a comprehensive analysis of regional strata, sedimentary facies, reservoir and oil reservoir characteristics in detail section, and comprehensive analysis and reservoir accumulation mode in this area, provide a reliable basis for oilfield exploration and development in the future.The Chang 6 and Chang 8 reservoir in Yeerzhuang mainly develop underwater distributary channel sand body in north west-south east. It continuous distribution on the transverse, and mutually superposed on the longitudinal, then provide the favorable reservoir space for oil reservoir. Chang 6 reservoir’s rock type is mainly lithic feldspar sandstone, and Chang 8 are lithic feldspar sandstone and feldspar lithic sandstone. Sandstone’s particles is finer, sorting is rounded. Filler content of reservoir is develop well, the ferrocalcite and kaolinite of Chang 6 are develop well, the chlorite and ferrocalcite of Chang 8 are develop well, Chang 6 and Chang 8 reservoir develop at night as long A period.Chang 6 and Chang 8 reservoir in study area belong to low porosity, low permeability reservoir. Chang 6’s physical property is slightly better, its average porosity is 11.22%, permeability is 0.52×10-3μm2. Chang 8’s average porosity is 9.29%, permeability is 0.47×10-3μm2, so, it is belong to low porosity and permeability reservoir. Chang 6 and Chang 8 reservoir have strong anisotropy, and Chang 8 is stronger than Chang 6. The porosity of reservoir is mainly intergranular pore, Chang 8’s intergranular pore is develop well, and Chang 6 is mainly develops intergranular pore, the second is the feldspar dissolved pore. Pore provides favourable space for oil and gas reservoir.Yeerzhuang reservoir develop more in the center of the delta distributary channel deposit, oil reservoir type is a typical lithologic reservoir, oil reservoir in Chang 8 develop well, drilling rate is higher. Chang 7 hydrocarbon source rock provides this area with relatively abundant oil and gas, migration and accumulation patterns of the formation (Chang 8) and store the assemblages of laying (Chang 6). Chang 6 and Chang 8 reservoir are mainly controlled by sedimentary facies, reservoir accumulation mode is due to excess pressure in vertical upward or downward migration of oil and gas. Chang 6 reservoir into model mainly for the oil and gas migration accumulation by superimposed permeable sand body and the accumulation of micro cracks. And Chang 8 reservoir accumulation patterns of the reservoirs are mainly for the reservoir accumulation and direct contact with hydrocarbon source rocks with superimposed sand body shipped accumulation of oil and gas.