Study On Mixed Deposition Of The First Member Of Shahejie Formation In Lixian Slop

Lixian slope is the main oil-producing block of Huabei oilfield. It is rich in oil and gas sources. It is an important pot to long-term migration and accumulation of oil and gas. And Shahejie formation is the main target layer of exploration and development. As the exploitation of oilfield has proceed into later stage, the exploration for oilfield needs a new understanding of objective layer. Besides, Sha 1 member of Lixian slope not only has a high potential to storage oil and gas, but also a lot of mixed deposition in Shahejie formation. It wants to provide the necessary support for the exploration of potential oil and gas, through explaining environmental characteristics of mixed deposition in Sha 1 member of Lixian slope, and as an example to explore the development law of terrigenous clastic-carbonate mixed deposition in lacustrine facies.The study is mainly based on the well-logging, mud-logging, core-data and synthetically considering the research achievements of predecessors. According to the theory and method of high-resolution sequence stratigraphy, and by the Standard for identification of base-level cycle and it's boundary, the study of Sequence stratigraphy is launched in Sha-1 member of Lixian slope. And the sequence stratigraphy framework which is composed of the basic unit of the middle basic level cycle is established. The Sha 1 member is divided into a long basic level cycle and three middle basic level cycles. At the same time, the types and characteristics of mixed deposition are summarized and analyzed in Sha 1 member.The study also researches the development characteristics of mixed deposition in different sedimentary facies, and analyzes the distribution characteristics and evolution laws of mixed deposition facies. establishes a mixed deposition model and finally explore the main controlling factor of mixed deposition.Research suggests that Sha 1 member is mainly developed braided river delta and lacustrine facies. mixed deposition mainly develop in shore-shallow lacustrine, some develop in the front end of braided river delta front. There are three types of mixed deposition, one is mixosedimentite, the second is mixed layer system, and the last one is piecemeal mixed sedimentary rock. And they can be divided in to lended mixing deposit and complex mixing deposit ?. There are a few Salutatory mixing deposit and complex mixing deposit ?. At Lixian slope, Sha-1 member, With the decrease of water depth and the climate changed from humid to dry, the size and the types of the mixed deposition development gradually decreases. Based on the comprehensive consideration of the research results of regional geological background and mixed sedimentary characteristics, types and mixed sedimentary facies, is confirmed that tectonism action, climate factors, sediment supply, hydrodynamic condition, lacustrine level change control the development of mixed deposition, and tectonism action and climate factors are the most important factors among these factors.