Evaluation Of Logging Interpretation Methods For Water-flooded Layers In L2 Block Of L Oilfield

L oil field was put into trial mining in June 1989,the L2 wells of the main oilfield block were divided into three sets of well patterns to develop three sets of layers.Nowadays,the recoverable reserves of L oilfield have reached 91.62%,the comprehensive water cut has reached 90.22%,and the oil of recovery rate is only 0.68%.The oilfield development has entered the stage of "high recovery,high water cut and low speed mining",the original oilwater distribution has changed because of long-term water injection,which has brought great difficulties to the logging evaluation work of the research block.It is able to classify the flooding level more carefully and accurately,which plays an important role in the second and third mining operations of the later oilfields,and can also provide technical support for oilfield development work.In this study,the three-layered system of L2 block was selected as the research object.The Triassic reservoir has good physical properties,and the reservoir porosity is between 15%and 24%,the permeability is mainly distributed at 50-500×10-3?m2,which belongs to the mesoporous medium and high permeability reservoir.In order to accurately evaluate the waterflooded layer in the L2 block,summarize the basic characteristics of the L2 block reservoir after fully understand the current status of the water-flooded layer in the block,the geological data,core data,test oil data,production dynamic data and well logging data collected.The characteristic response curve of the water-flooded layer is optimized after the study of the changes of shale content,grain size,petrophysical properties,formation water salinity and logging curve in the process of water injection development.It is considered that the resistivity curve,the natural potential curve,and the natural gamma curve are sensitive to the flooding of the block.The water flooding layer is qualitatively identified by the method of intersection graph,ant colony algorithm and support vector machine.After the core data is homing,the experimental data of 893 cores of 27 wells was combined to establish a pore infiltration model,the accuracy test is carried out,and the relative error is less than 8%.Based on the flow unit,the three saturation models were established by using mercury intrusion,nuclear magnetic and phase infiltration data.By comparison,it is considered that the nuclear magnetic data best meets the interpretation requirements with the highest precision.The relative permeability model is established and compared by Jones,Wilson and Whillite equations.Using the test area test oil and production data for multiple rounds of verification and debugging,the flooding level classification criteria suitable for L2 block features are summarized.Using the established model and the flooding level classification standard,41 wells in the study area were comprehensively processed.The results show that the quantitative model established by the research meets the precision requirements and provides a favorable basis for the second and third development of the oilfield.