Author(s): Sima Liqiang, Wu Feng, Ma Jianhai, Fang Guoqing, Yu Hang, School of Geoscience and Technology, Southwest Petroleum University, Yingdong E &D Integration Department, Qinghai Oilfield Company, PetroChina
Pages: 34-40
Year: 2014 Issue:  7
Journal: Natural Gas Industry
Keyword:  Qaidam Basin; Yingdong oil/gas field; mud logging; logging; excavation effect; NMR; oil and gas layer differentiation; GOR;
Abstract: In the Yingdong oil/gas field of the Qaidam Basin,multiple oil-gas-water systems vertically overlap,making it difficult to accurately identify oil layers and gas layers and calculate gas-oil ratio(GOR).In combination with test and production data,conventional logging,NMR and mud logging data were integrated to quantitatively calculate GOR.As to the identification of oil and gas layers,the conventional logging plays its role through the excavation effect of compensated neutron log,NMR plays its role through the different relaxation mechanisms of light oil and natural gas in large pores,while mud logging plays its role through star chart boards of gas components established based on available chart boards and mathematical statistics.As to the quantitative calculation of GOR,the area ratio of star chart board of gas component was first used in GOR calculation.The conventional logging data are actually modest in differentiating oil and gas layers due to the influences of formation pressure,hydrogen index(HI),shale content,borehole conditions and invasion of drilling mud.NMR is quite effective in identifying oil and gas layers,but cannot be widely used due to its high cost.By contrast,the star chart board of gas components is the most effective in differentiating oil and gas layers.The GORs calculated by using the area ratio of star chart board have been verified by various data such as testing,production and liquid production profile.