Structural Control Of The Carboniferous-Permian Shale Gas Reservoiring In Tunliu-Luan Regin

This paper selected the late Palaeozoic coal bearing series shale reservoir in Tunliu-Luan regin Shanxi province as the research object. Collected geological survey data, geological investigation, experimental test and were used in the study to analy the issues of Carboniferous-Permian shale gas geology characteristics, reservoiring process and impact of structure on shale gas accumulation. The results are as following.On the basis of field works and geological survey data, the study section is settled on the Taiyuan Formation to the Lower Shihezi Formation.This thesis gave a discussion and a summary of the tectonic characteristics and the tectonic evolution history of this target research area. In the study area, the total thickness of Lower Shihezi Formation, Shanxi Formation and Taiyuan Formation is about 189-434 m. It is presented as monocline with west-dipping in tectonic structure with zonation in east-west direction and segmentation in North-south direction. Since the late Carboniferous epoch, this research field has experienced three tectonic movements, namely the Indo-Chinese, the Yanshanian and the Himalayan periods respectively.On the basis of experimental analysis summarizes the development rule of the shale reservoir in the study area and optimization of potential target layer. The lower Shihezi to the Taiyuan Formation in L1 well Tunliu regin is made up of sandstones, mudstones, limestones and coals. Microporous and eyelet is the main storagespace. Porosity and permeability is low. Natural cracks are well developed. And Microscopic crack is the main. The shale reservoir of organic matter content is higher, and the evolution degree is at a maturity-high maturity period. The gas content is between 0.2m3/t~2.74m3/t, and shale reservoir gas content is higher which is adjacent coal.According to the evaluation index which the shale gas development zone is favorable, favourable targets D, B, C and A were selected. The C and A can be used as potential shale gas development reservior.Numerical simulation were used to study the accumulation process of shale gas and the tectonic control mechanism of this area. The model of burial history in this target area is roughly showed as “W” form, which includes the rapid burial period of the late Carboniferous epoch to the late Triassic epoch, the alternating epoch in the Yanshanian period as well as the continuous uplift of the crust. In generally, the thermal evolution and hydrocarbon generation of organic matters can be classified into four stages. During the late Carboniferous epoch to Triassic, this area is in the normal geothermal field. And intensity of hydrocarbon generation is not big. Migration is also weak and is given priority to with loss function. During the early Jurassic epoch to the middle Jurassic epoch, the heating temperature of shale is decreased. The evolution of organic matter of the shale progress is slow, and migration gradually strengthened and give priority to with loss function. During the late Jurassic epoch to the early Cretaceous epoch, palaeogeothermal rise sharply and a large number of thermogenic gas generated. Migration is stronger and give priority to with gas accumulation. During the late Cretaceous to Quaternary, geothermal gradient is close to normal geothermal field. Shale hydrocarbon generation effect ground to a halt and loss function strengthened.The control of recent structure of shale gas rich integration mainly reflected in three aspects respectively is buried depth, fault and fold. And presumably the Tunliu region is favorable for shale gas exploration and development.