Research On Seismic Stratigraphy And Petroleum Geology Of The Permian In Mahu Depression Of Junggar Basin

Under the guidance of advanced theories of sedimentology and petroleum geology the author has made a compositive studying of Mahu depression. Based on seismic data, logging data and well test data the research work has been carried out by means of seismic stratigraphy. The studying consisted seismic facies analysis, single well logging data analysis, sedimentary facies analysis, source, reservoir and cap rock together with formation pressure analysis. Petroleum geology conditions have been concluded especially on the distribution of sedimentary facies of the Permian, oil-gas traps and subtle traps. Several viewpoints were concluded as follows:1. On basis of introduction of the characteristics and evolution of the thrust belt of the northwest Junggar Basin, the structure and evolution of Mahu depression have been demonstrated, and structural maps of 4 strata were constructed. By the influence of regional structural movement, the structure styles of Mahu depression are simple, but the generation and migration of oil and gas are complex.2. By using seismic stratigraphy to lacustrine environment, sedimentary frameworks of Mahu depression have been studied. Results indicated that fan-delta were the dominant facies of Permian in Mahu depression.3. By means of sequence stratigraphy, the sequence frameworks of the Permian in Mahu depression have been established, which were divided into 5 sequences. And sedimentary system tracts have been studied.4. Factors, which control the forming of traps, are structural movement, sedimentary conditions, source, reservoir, cap rock and their combination.5. The most common types of oil-gas traps in Mahu depression are lithological traps together with the complex traps derived from them that controlled by lithology, anticline, fault and over pressure of strata, etc. Favorable prospecting targets of Mahu depression are pointed out.This paper has been accomplished on the basis of new theories. Significant research work on structure, sedimentation and their evolution of the Permian has been carried out. Deep underground prospecting of Mahu depression has been discussed.