Abstract The Member 1 of Paleogene Liushagang Formation is the major oil-bearing formation of WZ Oilfield in Weixinan Sag of Beibuwan Basin.The actual drilling results demonstrated its complex origin types，obvious change of sandbody thickness and strong heterogeneity of the reservoir which resulted that not only forecast of sandbody distribution is very difficult，but also the development result is greatly restricted.Sedimentary facies of the Member 1 of Liushagang Formation of WZ Oilfield is finely studied based on cores observation and analysis，in combination with the data of well logging and masterlog，the results show that it is dominated by steep slope fan delta of fault-depressional lacustrine basin，which is mainly the fan delta front subfacies containing abundant gravity flow sediments.The fan delta front subfacies can be subdivided into subaqueous distributary channel，mouth bar，distant bar and interchannel microfacies.The gravity flow sediments include gravity slump，debris flow，turbidity flow and fluidized flow，which are all generally small scale.The sedimentary microfacies maps of the key oil units of Ⅳ interval and Ⅱ interval of the Member 1 of Liushagang Formation are made by ingoing interpretation of the sedimentary microfacies on a single-well section and fine multi-well correlation.According to the maps the whole sedimentary framework of the area is a stable fan dela front and the provenances are from north and northwest.The gravity flow deposits are common from fan delta front to prodelta areas because of steep slope.Moreover，the depositional model of deeper water of steep slope fan delta is established based on characteristics and distribution of microfacies.Analysis of physical property and oil potential of the different microfacies sandbody shows that the subaqueous distributary channel is the best，mouth bar is better，distant bar and distant turbidite are bad.A favorable development area and an adjustment well are proposed which achieves several dozens of meter oil beds and play an important role in production and increasing reserves.
About author: Yang Yuqing， born in 1963, is a senior engineer with a Ph.D.degree. Now he is engaged in sedimentology and logging geology. E-mail: yangyq@cosl.com.cn.
Cite this article:
Yang Yuqing,Cui Weiping,Cai Jun et al. Sedimentary facies of the Member 1 of Paleogene Liushagang Formation of WZ Oilfield in Weixinan Sag，Beibuwan Basin[J]. JOURNAL OF PALAEOGEOGRAPHY, 2012, 14(5): 607-616.
Yang Yuqing,Cui Weiping,Cai Jun et al. Sedimentary facies of the Member 1 of Paleogene Liushagang Formation of WZ Oilfield in Weixinan Sag，Beibuwan Basin[J]. JOPC, 2012, 14(5): 607-616.
