The Study Of Characteristics Of The Chang6~1Reservoir In Northern Secton Of Liugou Field, Erdos Basin

The Erdos basin is an oil-bearing basin. It distributes structurely as an asymmetricrectangle trends from north to south, gentle in the eastern limb, and steep in the west.The structure is simply and dominant with the nose structure. The layer extendssmoothly with the angle less than1°. The Liugou field is the main one of Wuqi NO.1factory, located in the monocline which dipped to the west. The interval are large inLiugou field, and there are Yan9、Yan10、Chang2、Chang3、Chang4+5andChang6reservoirs from the top to bottom, The Yan101、Yan102+3are the mainreservoirs, Chang4+51、4+52occurred rarely in the field, and the Chang61is themain studying reservoir in this paper.The Chang61reservoir is extra low permeability which productivity declinedeeply, and the eadge and bottom aquifer are inactive. The dissaving level is low, andit was hard to make up the pressure in nature. The water-cut is high in the beginningbecause of the high original water in most of the reservoirs. The well pattern is perfectGeographical but water flooding reserve is low because of the plane heterogeneity.The structures and reservoir characteristics, as well as fluid, are studied in thisdissertation on3d dimension based on the composite using of geological, drilling,logging and dynamic data. The main achievements is as follow:It is observed that the reservoir is a monocline trends west, and the tectonicmovement is gentle. The structure is simply with layer angle less than1°. Local nosestructure with minor fluctuate, which axis from west to east or northeast to southwestbecause of the imbalance tectonic and differential compaction, is dominant.The Chang61reservoir distributed the delta front sub-water channel, levee andsub-water bay between distributary. The sub-water distributary, which overlappedfrequently in the northern, trends from north to south is the main oil-bearing zone inChang61reservoir. The sub-water distributary sand in south zone is rare and distribuerarely.The rock type categorized as feldspar and lithic feldspar sand. The inter matrixpore is dominant, in-matrix dissolve pore also semi-dominant, in-crystal pore andmicro fracture are the least pore type in Chang61. It is a middle pore and extra lowpermeable reservoir with average porosity13.8%permeability11.5×10-3μm2,respectively.The OOIP is299×104t based on the volumetic method, recoverable reserve is53.82×104tV, respectively. And the solution gas reserve is2.6×108m3. Thecorresponding reevaluation is done also.