The Research Of Reservoir Characteristics Of Funing Formation In Gaoyou Depression

The Gaoyou depression is the major oil exploration zone in Jiangsu oil field. The Sha40 Wa2 and Hua11 oil bearing areas which were found resent years have low oil test yield due to deeply buried reservoir, poor physical property, thin monolayer thickness and natural energy deficiency. As a result, the reservoir characteristics research and advantage reservoir distribution regular research can provide the next exploration direction.Based on the comprehensive application of core, well logging, testing, and assaying data, the reservoir characteristics, secondary porosity zones and compartment characteristics, lower limit of petrophysical parameters of effective reservoirs, controlling factors and evaluation of effective reservoirs of the Funing Formation in Gaoyou Depression were systematically studied.The sand bodies of underwater distributary channel, mouth bar and sand sheets were developed in Funing. The diagenetic stage of the reservoirs is divided into late diagenetic substage A1 and A2, and late diagenetic stage B. The deep reservoirs mainly developed compaction, cementation, metasomasis and dissolution. The reservoir spaces include intergranular dissolved pore, intragranular dissolve pore,mold pore, especially big pore and micro crack. The intergranular dissolved pores are the main reservoir space. The pore of reservoir physical parameters is mainly 15%,and permeability is mainly 1~10×10-3μm2. Several secondary porosity zones exist in the longitudinal direction in Funing Formation, and the Shanian, Huazhuang and Wazhuang regions exist in the Plane, and the most developed is E1f3. The lower limit of petrophysical parameters of effective reservoirs is closely relative to buried depth. and they are decreased regularly with the depth increased. Sedimentation is the most important controlling factor to form deep high quality effective reservoirs, and abnormal pressure zone is more effective than diagenesis in controlling the formation of effective reservoirs. There are many favorable factors for developing high quality effective reservoirs, that is, lithology is thick sandstones and pebbled sandstones, sedimentary facies are the underwater distributary channel, diagenetic stage is late diagenetic substage A1, and formation pressure is abnormal. According to the analysis of main controlling factor of deep effective reservoirs, combining the analysis of effective porposity and permeability and production, the deep reservoirs are classified into 8 categories, of which,ⅠandⅡ1 is the high quality effective reservoirs,Ⅱ2 andⅢ1 is middle effective reservoirs,Ⅱ3 is the low effective reservoirs, andⅢ2,Ⅲ3 andⅣi s noneffective reservoirs.