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Sichuan Gongshanmiao Construct The Sand Section Of The Reservoir Fracture Prediction And Fracture Porosity Numerical Evaluation

Posted on:2005-01-09Degree:MasterType:Thesis
Country:ChinaCandidate:L P LiuFull Text:PDF
GTID:2190360152956473Subject:Mineral prospecting and exploration
Abstract/Summary:PDF Full Text Request
The member Sha-1 oil reservoir in Shaximiao Formation of Jurassic in Gongshanmiao structure in the center of Sichuan basin was an important discovery of oil exploration achieved by the Southwest Oil and Gas Field Branch, PCL, during the Ninth "Five-Year" plan, with a high deliverability. But it is a structural-lithologic combination trap, and the fractural-porous preservation type reservoir. The well-developed faults and fractures not only greatly improved the percolation capacity of the reservoir, but also provided important pathways for oil and gas migration and accumulation. So, the question of fracture evaluation must be solved immediately at present according to Sha-1 oil reservoir.In this project the characteristics of fracture development degree, regularities of distribution, genesis, type, bearing of trend and fracture porosity etc. have been predicted and assessed quantitatively or semi- quantitatively in 2D space by a set of technical method, which is basing on a great deal of information of areal structure investigation, data of 3D seismotectonics fine interpretation and actual material of well logging, drilling and production test etc., directed by the theories of structure geology, rock mechanics and geomechanics etc., supported by structure analysis, numerical analysis and mathematical statistics. Through in-depth study we can come to a conclusion as the following.The structures in the north of center Sichuan basin have experienced the function of meridional equable compressional force in the metaphase and anaphase of yanshan movement and transpression which is from northeast to southwest in himalayan movement. Accordingly, Gongshanmiao structure and fault-fracture system were also formed on the action of the above two stage. The degree of fracture development in Sha-1 reservoir is quite high, but distributes very unevenly because of the large horizontal change of lithology. It is principally controlled by faults and folds have less effect on it for low structure extent. There are abundant fracture types including high angle shearing cracks, middling or low angle shearing cracks, transmeridional high angle tension cracks and meridional vertical shearing cracks. There are many bearing of trends of fractures including northeast, northwest, meridional and transmeridional fractures, among which northeast fractures and transmeridional fractures constitute the main body of fracture system in Gongshanmiao structure. Fracture porosity is the highest in the zone of transmeridional faults, and is higher in northeast faults than in northwest and transmeridional middle or small faults. The zone of middling and small type faults developed and its vicinity, and the region with fracture porosity varying from 0.01% to 0.04% are the favor accumulation area, especially in the vicinity of northeast normal faults. The corresponding area of meridional buried faults developed which is influenced by dip offsetting of nether faults and easy to break to form abundant fractures and high fracture porosity and is not destroyed by faults, is in favor of oil and gas accumulation and the important exploratory development target.The results of comprehensive prediction of fracture and fracture porosity numerical evaluation can provide a reliable geologic reference and point out the way for the next exploratory development in the member Sha-1 oil reservoir in Gongshanmiao structure.
Keywords/Search Tags:Center of Sichuan basin, Gongshanmiao Structure, The Member Sha-1 Reservoir, Tectonic Origin, Fracture Prediction, Fracture Porosity, Numerical Evaluation
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