Study On The Extra-heavy Oil Reservoir Heterogeneity And Remaining Oil Distribution Of Du 229 Block's Xinglongtai Oil Layer

Du 229 block is an important exploitation block of Liaohe oilfield. The target layer is Xinglongtai oil layer, which is a typical extra-heavy-oil reservoir. The hydrocarbon reservoir assemblages are Xing II to Xing VI.The former five oil pools belong to Front Fan delta sedimentary. The last belongs to turbidity sedimentary. The reservoir depth is about 840 meters to 1100 meters and the thickness of oil layers is from 60 meters to 150 meters. Since the beginning of exploitation, three major periods had been experienced:rapid growth stage,short stage of stable and high production and the lasting reducing stage. Now,3.96 million ton oil was recovered and the degree of reserve recovery is about 19.2%.Treatments such as heavy repair,layer converting were applied to relieve the production decline and the result is quite good. Nowadays,the production problems are extremely prominent. The CSS development style is hard to continue and alternate of the development method is in need.In this paper,reservoir engineering method was applied to evaluate the production condition of Du 229 block and try to study the affecting factors to the exploitation of extra-heavy oil reservoir. Reservoir heterogeneity is considered to be the inner and principal factor which affects reservoir development level and is mainly controlled by microfacies. The development technologies affect exploitation result. In this paper,static understandings combine with reservoir performance analysis was used to study the remaining oil distribution laws of plane,intrabed and intraformation. On the planar,non-heat communication areas among wells and areas uncontrolled by wells are main areas of remaining oil existing. Affected by both geological and development techniques,the Northern low level efficiency area and area in Mid-Southern invaded by edge-water are remaining oil rich domain. There exists most remaining oil in the main microfacies such as subaqueous distributary channel and channel bar .Vertically,remaining oil mainly exists in imperforated intervals and inefficient layers while production in long interval. Remaining oil mostly lies in the lower-middle part of the reservoirs. Distribution law of remaining oil in extra-heavy oil reservoir was presented. Finally,based on the research result,infilled wells were designed to improve the reservoir reserve control level. And,treatments such as layer converting and separated layer steam injection,multi-wells CSS together were also put forward to improve the steam stimulation effect. SAGD was considered to be fit for the development of extra-heavy oil in Du 229 Block. When the well pattern is ready, SAGD will be carried out in preferable areas. According to the experimental result in neighbor area,higher recovery rate was expected to obtain in this extra-heavy oil reservoir.