Fine Characterization Of Xin-25 Extremely Complex Fault Block Reservoir

Xin-25 block is a typical representative of extremely complex fault block reservoirs,with many faults and extremely developed low-grade faults.The oil-controlling faults in the work area are not accurately described,which makes it difficult to exploit the remaining oil along the high part of the oil-controlling faults.Moreover,the extremely developed low-grade faults are difficult for interpretation and clear understanding of the fault system,and there are still many oil-bearing fault blocks with low well control degree and no wells encountered.How to improve the interpretation accuracy of oil-controlling faults and the effective identification of low-grade faults has become an urgent problem in the exploitation of remaining oil in extremely complex fault block reservoirs.In this paper,Xin-25 block is taken as the main object to tackle the key problems.Based on the re-understanding of reservoir geology,we focused on fine characterization of oil-controlling faults in extremely complex fault block reservoirs,identification and description of low-order faults,deepening research on remaining oil enrichment mode in extremely complex fault block reservoirs,and carrying out the study on adaptability of enhanced oil recovery technology in complex fault block reservoirs combined with remaining oil enrichment mode,thus providing technical support for the efficient development of the same type of oil reservoirs.A fine characterization technique of fault edge based on multivariate comprehensive calibration and near-horizon tracking was proposed to characterize oil-control faults,and the factors affecting the fault edge characterization accuracy were clarified.It was found that the high-position fault-block without well control was formed by displacement of several oil-control faults,and the newly added recoverable reserves were estimated to reach 435,000 tons.Four small fault identification modes have been established,including the seismic attribute analysis mode under the indication of breakpoints,the seismic comparison analysis mode for uncertain breakpoints,the geological feature analysis mode under the constraints of seismic interpretation,and the seismic screening analysis mode under the control of dynamic characteristics.And at the same time,10 new small faults were added in the work area,and 4 small fault blocks were found without wells,and the new geological reserves are estimated to be 280,000 tons.The technical countermeasures for enhancing oil recovery were proposed for the remaining oil of high-position linear fault block and the remaining oil of non-well-controlled fault block,which are multi-target complex structure wells near faults and multi-target complex structure wells across faults.A cross fault multi-target complex structure well Xin43-18(inclined)has been designed and drilled.The well is 12 m away from the fault,and 17 oil layers have been drilled with an effective thickness of 72.7m,with a very significant effect.It is estimated that the oil recovery can be increased by 2-3%by the reservoir engineering method.The formation of the above technical countermeasures is of great significance to the production stability of Shengli Oilfield during the period of the 14 th Five-year Plan.