The Study Of Facies And Reservoir Characteristics Of Donghe Sands In The Southwest Of Tahe Oilfield, Xinjiang

Donghe Sands, a sands body within Donghetang Formation of Later Devonian, had been discovered in several wells in southwestern Tahe Oilfield since 2000, it was mainly composed of light-gray quartzose and lithic quartzose sandstones, the interpreted column filled hydrocarbon was over 60 m with the evidence of wireline-log data, and hydrocarbon indications occur frequently in the drilling. It was overlain an unconformity which was resulting from long period erosion of the uplifted Northern Tarim basin due to the Early Hercynian orogeny during the time of transgression in Later Devonian.By use of the data of thin section and core, we make a detailed study about sedimentary facies and reservoir characters. The results show that:1. 6 microfacies including foreshore, backshore, shoreface and a beach sedimentary system have been identified from the Upper Devonian of the southwest of Tahe oilfield.2. microfacies of single well and contrast of microfacies of adjacent wells have been ascertained, we find that the sand body mainly with foreshore and shoreface is comparably stable in space, so we should attach great importance to the exploitation in these region.3. Judging from the thickness, the reservoir is developed,Northwest sand thick and thin to the southeast, the reservoir has development intergranular pore, has a good porosity and permeability conditions for better reservoir of Classâ…¡rock.4.By use of the method of Kridge, we make a forecast of thickness and distributing of the reservoir. It provide quantificational data to evaluate the thickness of reservoir, and it shows that the west and southwest of the research region have better interests for exploitation.In all,the Donghe Sands overlain the oil pools of Ordovician have a good prospection for oil exploration, and it can to be the new domain and succession for expanding of Tahe Oil Field.