Study On The Oil & Water Distribution Of The 1^st Member Of Shahejie Formation In 3^rd Structure Of Nanpu Sag

Nanpu 3rd structure is located in the south of Nanpu Sag and north of Shaleitian salient.With the deepening of exploration work,industrial oil flow was found in the Paleogene Shahejie Formation,the 1st member of Shahejie Formation(Sha 1 member)is one of the main productive layers in the area.For the fact that the research degree of reservoir characteristics is low,oil and water distribution is complex,reservoir types and oil-water distribution regularity are lack of clear understanding.This thesis comprehensively utilizes geological,seismic,logging,analysis and production data,analysising the Sha 1 member reservoir basic geological characteristics,studying the oil-water distribution characteristics and main contolling factors,discussing the region oil-water distribution regularity and pattern.The following results were achieved:(1)Nanpu 3rd structure is tectonically high in the south,low in the north,and high in the west,low in the east.The main part is the anticline which is complicated by faults.Fault-block and faulted nose tectonics are developed.The main types of Sha 1 member reservior are tectonic reservoir,tectonic-lithological reservoir and lithological reservior.(2)The main types of Sha 1 member sedimentary facies is braided river delta front,which mainly consists of 4 types,such as underwater distributary channel main body,mouth bar,lateral border of underwater distributary channel and underwater inter-distributary bay.The development and distribution of sand body are mainly in the south along the direction of provenance.The channel main body has good physical properties.Vertically the porosity and permeability decrease with increasing depth.The main diagenesis includes compaction,cementation and dissolution.(3)The crude oil and formation water properties of Sha 1 member have been summarized.The crude oil of Sha 1 member has high volume factor,single degassed gas-oil ratio and compression factor,low formation oil density and viscosity,which belongs to volatile reservoir fluid.The formation water main type is NaHCO3,which is characterized by high Cl-Mg coefficient and low coefficient of desulfurization,which reflects favorable closed condition.(4)The oil and water distribution characteristics of Sha 1 member have been illustrated.Vertically the oil layers distribute in SQEs1 z lacustrine regressive system tract.Oil layers distribute in high part of anticline and faulted nose tectonics near faults,and water layers mainly distribute in structural low part,which is characterized by oil in high part and water in low part.Oil and water layers are contiguously develop in the plane and also follow the regularity that oil in high part and water in low part.The oil-water distribution is mainly controlled by positive structure,fault,unconformity,sand body and sedimentary micro-facies.(5)The oil and water distribution pattern has been built.The reservoirs of Sha 1 member are layered edge water reservoirs controlled by structure and lithology.The hydrocarbons generated in underlying source rocks migrate along the oil source faults to the sand bodies which has good physical properties in SQEs1 z,and are sheltered by overlying unconformity mud rocks and accumulate in structural high part of positive structures and faulted nose tectonics near the faults,which forms the pattern of oil in high part and water in low part.