Purse Field Block Xujiahe Sec, Sec Reservoir

This paper guided by sedimentographics of sedimentology,stratigraphics, and logging geology as well as seismic reservoir prediction, the reservoir from xujiahe the member 2 and member 4 were studied and accounted that its sub-environment was lacustrine clastic shoreline and its microfacies were beach and bar sands,dust sand,corcass and tempestite and fluviatile deposit/fluvial sediment were found in bottom of xujihe member 2 and south part of xujiah member 4^th. The lithology of reservoir were mainly, fine-grained lithic sandstones and lithic quartz sandstones, which are relatively densedwith a little siltstones that created overlying sandbody in the aggressive and regressive movement of lake basin. The member 4^th were reservoir with low porosity and extremely bad permeability and their porosity was mainly between 5% and 8%, some higher than 8%; the member 2^th are gentle higher bigger porosity and extremely bad permeability, porosity of most of its beds are higher than 8% and there are strong heterogeneity well developed among such two members and their averaged porosities are always smaller than 1×10^-3μm², which defined the reservoirs are one with small pore and thin throat amd the pore forms are remainder intergranular pore, secondary pore, micro-pore and micro-fissure. The quality of reservoirs is how many pores there after the rocks were compressed and how many sand rocks are there in the reservoir and the most preferential factors are coarse quartz sandstone and quartz sandstone with great feldspar and second is how degree the rim cementation of rhipidoith. The low limit of member 2^th and member 4^th are 8% and 6% respectively, the permeability 0.2×10^-3μm² and their single beds are generallt thin and accumulative thickness varied so great based on the logging interpretation, which has distributed horizonal as masses of cords and connectivity are so bad. The good reservoir of xujiahe member 4^th are distributted vertically in the middle and bottom of its bodied, which are represented by zone from bao well 45 to well 001-16 and area from bao 41 to well 39; The good reservoir of xujiahe member 2th are distributed horizontally in the middle and bottom of its bodied, which are represented by zone from bao well 24 to well 001-16 and area from bao 46 to baoqian well 204. Based on reprocessing of 2D sesimic and seismic response modeling, combining with fruits of logging interpretation, through conversion of verged velocity and GR, Tendency of the Biodiversity Variation of xujiahe member 2th and member 4^th gained better dovetail agreement.