Study On Logging Evaluation Method Of Chang 4+5 Reservoir In Yizheng Oilfield In West Ordos Yanchang Oilfield

Chang 4+5 of yizheng oilfield in west odors basin yanchang oilfield is a typical low-permeability litho logic oil reservoir. Currently, with the development of chang 4+5 reservoir, gradually found that the high gamma reservoir, high resistance reservoir and low resistance reservoir exist in well logging interpretation, the relationship between reservoir oil distribution situation and the well curve is complex, it is hard to do logging interpretation, the improve of logging interpretation meet rate has been seriously restricted,effecting the Chang 4+5 reservoir exploration development, so a series of effective logging interpretation method need to be established in research area.This thesis researched the chang 4+5 reservoir of yizheng oilfield in west yanchang oilfield. Based on the data of geology, core, logging and production, studies of layer fine division and correlation, sand micro-structural characteristics, sand body distribution and sedimentary characteristics, reservoir characteristics and the four properties relationship, reservoir logging interpretation method in study area target layer should been done.Studies have shown that Chang 4+5 reservoir in study area can be divided into two layers: chang4+51, chang 4+52; overall structure is simple, the northeast structure is high and southwest low,and develop inherited small nose shaped uplift and a series of small nose shaped uplift structure missing from the East to West, the structure is changing slowly in the East, and transform violently in the West; sand body distribution show block, scalability is not very good, locally develop thick sand in chang4+51 and chang 4+52 small layer, generally, the sand of chang 4+5 develop well, scalability is not very good, connectivity in the plane is general. Within the study area is shallow-water delta front deposit, sedimentary micro-facies mainly include underwater distributary channel, levee and distributary bay; the minerals of sandstone fragments in chang 4+5 oil layer mainly are feldspar, quartz is the second, and chang 4+5 is tight sandstone reservoirs. Sand particle separation is medium, size is uniformity, mainly include poor separation and good separation; round is mainly include subangular shape and subround-subangular shape, roundness is moderate, fillings of sandstone mainly are authigenic minerals,and pore type mainly are secondary pore, the average porosity of reservoir is 12.4%, the average permeability is 0.99×10-3μm2; the low limit of chang 4+5 reservoir porosity is 7%, permeability is 0.2×10-3μm2, AC is 207μs/m, resistivity is 9.6Q.m, and the oil saturation is 34.5%, establish multi-parameters overlay plot and crossplot to judge oil-bearing,divide the low limit of reservoir logging interpretation, form multi-parameter and multi-method identification technologies with low resistivity reservoir, high resistivity reservoir, high gamma reservoir and conventional oil-water layers coexist in an oil field with changing formation water salinity.This research,carried out and completed, is of great theoretical and practical significance.