Research Of Sand-body Distribution Of Upper Karamay Formation In The 8th Zone Of Karamay Oilfield

The upper Karamay formation oil reservoir in the 8th zone of Karamay oilfield located in Baijiantan area, Karamay City. This paper aiming at the problem of the dispersion of the single sand-body in this oilfield during the high water-bearing period, the data of logging, geological logging, oil testing and production testing, well history and dynamic detection was gathered in this paper. By comprehensive analysis these data, based on analysis of rock-electricity of coring well, developed reasonable standards and precision of classification and correlation, established standard section, then carried out fine classification and correlation on small layer in the entire area. Based on fine classification and correlation of sand-body in vertical, targeting single sand-body, completed the planner distribution graph of the sand-body, cleared it's planner distribution. Made the following main conclusions:(1)In lithologic association, the layer in the study area is mainly interbedded unequal thickness by sandy conglomerate, pebble sandstone and mudstone, followed by feldspar and quartz, was second round-subangular.(2)The front-delta and fan delta plain subfacies was developed in this area, and the front-delta can be divided into four microfacies: distributary channel, point bar, beach and the gulf between distributary channel; the fan delta plain subfacies can be divided into subaqueous distributary channel, subaqueous inter-channel bay and front inter-channel bay.(3)The stratigraphic cycles of the upper Karamay formation in the study area was relatively complete, there was distributed unequal thickness mudstone at the top and bottom in every cycle. Based on core description, debris logging and correlated analysis data, reference original stratigraphic division results, the upper Karamay formation was divided into five sand substrata, ten sandstone layer and nineteen single sandstone layer, the thickness of every single sandstone was relatively stable.(4)The form of the single sand-body in the plane change greatly, expect dispersing isolated form and long banding form, there is also composite irregular flakes, wide belt form. Statistics shows that, there is significant positively correlation between the average length and the average width in the study area. The distribution area of the single sand-body has a direct proportion with its average thickness, but this correlation was weak. On the vertical horizon, the single sand-body and mudstone in the S5-S3 sandstone layer was divided between each other, their distribution was not stable although the single sand-body was developed. The form of the single sand-body distribution on the plane was mainly lens-shaped, banded and thin sheets shape were followed. Because of the migration of the distributary channel the form of the single sand-body in the S1-S2 sandstone layer mainly displayed composite striped, banded and composite thin sheet shape.(5)The upper Karamay formation reservoir in the study area was a set of medium-low porosity, medium-low permeability reservoir, the correlation between the porosity and the permeability of the reservoir was weak, the heterogeneous degree was great, the distribution form of the oil layer were mainly Contiguous narrow banded, it was controlled by the distribution form of the sand-body significantly.