Study On Reservoir Characteristic Of The Chang-8 Member Of Yanchang Formation In Huangjialing-Shuimogou Of FuXian Project,Ordos Basin

Chang-8 reservoir member of Huangjialing-Shuimogou in Fuxian project of Ordos Basin got a breakthrough in 2009. The oil-bearing area was determined.The results indicated a bright exploration prosepect of Chang-8 member. But because of low exploration degree, and lack of any lysis data,the research degree of reservoir characteristic is low. On a certain degree, oil exploration of this area is limited.The thesis is based on previous research, guided by Modern petroleum geology theory, combined with outcrop section, cores, logging, region data and single well data, using kinds of analysis data, a thorough research is conducted from geology settings, depositional system, rock constituent and micro pore structure. The following results are studied: Huangjialing-Shuimogou Chang-8 formation is divided into Chang-81 and Chang-82. Chang 8 is delta front sedimentary facies which concluding underwater distributary channel and interdistributary bay sub facies. On the plane,4 underwater distributary channels developed in Chang-82 and 3 underwater distributary channels developed in Chang-81. The reservoir rock type of Chang 8 is mainly arkose sandstone and clastic constituents is mainly arkose averaging 49.2%, Quartz 29.4% and cuttings 15.8%. Sorting features of sandstone clastic particle is good, psephicity is mainly subangular and subrounded, secondly subangular, subrounded. Point-line contact is the mainly type of contact. Secondly type is line contact and concavo-convex contact. The type of cementation is mostly porous cementation and secondly film pore cementation. The porosity of Chang-8 reservoir is between 6%-13%, averaging 8% and permeability of Chang 8 reservoir is between 0.15-0.45×10-3um2, averaging 0.28×10-3um2. It is the ultra-low Porosity and permeability reservoir with strong heterogeneity. On the basis of oil production test and interval transit time-resistivity relation, the lower limit of Chang-81 oil sub group effective reservoir is resistivity≥23Ωm and interval transit time≥229μs/m. The lower limit of Chang-82 oil sub group effective reservoir is resistivity≥19Ωm and interval transit time≥228μs/m. The Chang-8 reservoir should be divided into 4 types and the percentage of type III reservoir of Chang-81 and Chang-82 is 53.4% and 65.5%. The Main Controlling Factors of Chang-8 reservoir distribution is sedimentation and reservoir physical property.