| With the strengthening of shale gas exploration,more and more attention has been paid to the study of influencing factors of shale gas reservoir performance.In the process of burial diagenesis of shale reservoirs,they are also reservoirs,which are usually complex and have complex diagenetic processes.Organic matter evolution plays an important role in controlling pore size and specific surface area.According to the core sampling of the wufeng-Longmaxi formation in the study area,it is found that the organic matter is characterized by high maturity,high total organic matter content and high oil generation potential.The low maturity black siliceous shale of the Shangsi Dlong formation,Guangyuan,which is basically the same as the study area,has been selected.The detailed experimental process and steps are made by controlling the important parameters such as temperature,pressure,medium,heating mode and so on,in combination with the evolutionary burial history of Peng Pang 1 well.At the end of the thermal simulation experiment,the samples collected from the experimental process were collected.Then using the data of rock thin slice identification,X diffraction,argon ion scanning electron microscope and FIB micro structure observation technology,the occurrence state of different types of pores in shale is observed systematically,and the evolution process of various kinds of pores in the process of shale from initial deposition to final diagenesis is analyzed,and the different types of organic matter and surrounding rocks are identified.The relationship between the spatial distribution of inorganic minerals,the development degree of organic pores(size,shape and quantity),and the main organic pore space of shale gas enrichment.Then through the rock pyrolysis,whole rock mineral analysis,FIB-SEM three-dimensional structure analysis,nitrogen adsorption desorption and other experimental analysis,the shale reservoir properties with the organic matter thermal evolution process of quantitative analysis.The main achievements of the paper are as follows.(1)It is considered that under the same porosity,shale is far larger than the surface of sandstone,and the amount of adsorbed gas is greater;shale reservoir is more focused on the specific surface;the specific surface depends on the porosity and the number of pores;the porosity and the specific surface(the number of pores)determine the adsorption gas of the reservoir.(2)Through the thermal simulation experiment,we think that organic pores can also be formed during the process of biochemical and low-temperature stage,and the formation and evolution of organic pores are heterogeneous,and clay minerals have a certain catalytic effect on the evolution of organic matter,and the organic matter contraction joint / organic matter edge joint.It is an important space for the occurrence of shale gas.(3)The experiment of diagenesis shows that with the increase of maturity,the organic pores are increasing from the face rate and connectivity,and the average residual carbon ratio of the marine kerogen is 58.9%,that is,the average only 41.1%of organic carbon can eventually convert to oil and gas.When the simulated temperature reaches 450 degrees,that is,Ro=2.2,organic carbon.The amount of transformation and porosity increased gradually.The evolution of organic porosity in well Peng 1 in Pengshui area is predicted according to the evolution rule.The process of organic matter pore evolution was also reduced.(4)Studies show that the face rate of shale reservoirs is increasing with the thermal maturity of organic matter.The change of specific surface is roughly the same as that of micropore.The number of micropores is the key factor determining the specific surface.In the later period of the thermal simulation experiment,because of the diagenesis such as compaction,the large pores and mesoporous pores are gradually transformed into micropores and the porosity decreases,but the shale reservoir has a sharp increase in the surface area because of the increase in the number of micropores. |
PDF Full Text Request