Fault Systems And Reservoir-controlling Mechanism In Kelasu Thrust Belt Of Kuqa Basin

Kelasu thrust belt is an important Oil and gas structure in Kuqa basin. In recent years,Dawanqi oilfield is found in the Neogene and Quaternary shallow strata. As the oil and gasexploration in deeper strata, many Gas reservoirs, such as Kela2, Kela3, Dabei1, Dabei3,Keshen2, are found under salt. All these show the wide prospect of oil and gas exploration.But the distribution of gas and water is uniformity, prediction is difficult, and increased therisk of natural gas exploration.Based on the analysis of the geological characteristics of Kelasu thrust belt, the paperfirst clarified the distribution of faults and fault systems, with Dabei1gas field for researchwork area, according to the3d seismic data volume, the reference of the past structureinterpretation schemes, summarized the characteristics of fault. Through the existing material(pressure data, gas composition, water component), for typical reservoirs anatomy of Db1gasfield, study the distribution of natural gas which has been found. Based on the lateral sealingability of fault and the influence of the cracks on reservoir two aspects, the use of fault sealingquantitative evaluation technology and FaultED crack prediction technology, deeply discussedthe control mechanism of fault, summarized the influence factor of faults in Db1. In the end, aviable method for gas water interface prediction was established, and gas water interfaces ofDB1gas field were initially forecasted.Comprehensive consideration of the fracture geometry characteristic, deformation times,deformation properties and distribution characteristics of stress field in different periods,Kelasu thrust belt is divided into four fault systems, which is inverted faults, thrust fault onthe salt, normal faults with sedimentary and imbricate fault under the salt.Using four methods, the analysis of the fluid related parameters on both sides of faults,juxtaposition, the SGR method, fault reactivation, to evaluate fault sealing. The results showthat F6is open, lateral sealing capacity of F2and F3control now gas water interface of Db1and Db101fault trap, F4, F5, F7have high sealing ability (can support of hydrocarboncolumn height more than traps close).Gas water interfaces of all fault trap which is predicted is lower than those aredetermined according to the breakpoint, except Db101and Db103fault trap. So this workexpanded natural gas exploration area in Db1gas field. With the FaultED method for fractureprediction in Db1gas field, the simulation results show that the nearer to fault, the morefissures for the formation. The greater the fault is, the more fissures for the formation. Thus,the formation around the Db6well and Db104well have high fracture densities, namely thepermeability of reservoir is not the cause of their defeat.