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The Finite Element Simulation Of Fracture In Buried Hills Of Jizhong Region

Posted on:2011-10-14Degree:MasterType:Thesis
Country:ChinaCandidate:Z LiuFull Text:PDF
GTID:2120360308490356Subject:Geotechnical engineering
Abstract/Summary:PDF Full Text Request
Wiith the oil and gas exploration field expanding ,the study of development on buried hills reservoir has become an important research area,and the distribution of fracture development is the key issue to be resolved. Takeing the north region of Renqiu buried hill Ordovician in Jizhong region as example,the distribution of the crustal stress of the researched region was simulated by using ANSYS,based on finite element theory and logging data.The fracture distribution of this area was predicted effectively combined with rock failure criterion. According to the research, the following results can be obtained:(1)Structural fracture is the major crack type in the north region of Renqiu Ordovician,and other crack types are minor.(2)It is proved that the method of determining the rock mechanical parameter by acoustic logging is a valid way to define rock mechanics parameters.(3)By comparing simulated with actual values,it can be deduced that the boundary condition acquired by polybasic linear is closed to Actual state.(4)According to simulate results,the crustal stress distribution at the top of the north region in Renqiu Ordovician was found as follows: the maximum horizontal principal-stress, which presents as pressure stress, focus between -61MPa and -118MPa in this area, and the direction of crustal stress in middle-north part is in north-west , in north part is gradually becoming in south-west. The minimal horizontal principal-stress, which presents as pressure stress too, focus between -31MPa and -91 MPa, and the direction of crustal stress in north part is in north-east, in south part is gradually becoming in east-west. Besides, the fault zone has an obvious effect on the distribution of crustal stress in the research area, and the area adjacented to the fault zone is gradient zone with variational stresses.(5)Based on the crustal stress distribution and combined with Coulomb- Mohr shear criterion and Griffis tension criterion, shear crackling rate and tension crackling rate was acquired by rock fracture Formula. It is found that the rock crackling rate surrounding the fault or in the fault is bigger and the degree of fracture development around the fault is higher. Besides, the feature of crack distribution is area or block. Compared with the well points plan,it shows that many well points mainly distribute in the area which has a high degree of fracture development. On the contrary,Only a few well points distribute in the area which has a poor degree of fracture development. Based on the results have been mentioned, the analysis results can be considered consistenting with the actual situation.
Keywords/Search Tags:finite element, crustal stress, the north region of Renqiu Ordovician, crack distribution
PDF Full Text Request
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