Research On Horizontal Well Formation Evaluation Method Based On Acoustic And Resistivity Logging

Currently the horizontal well technology has been widely used in the production of domestic and international oilfield oil fields.This technology plays a significant role in the development of unconventional oil and gas reservoirs.The exploration and development cost can be reduced by using horizontal well technology,which has become an effective means of oil and gas production.It can also improve well productivity and oil recovery.With the development of horizontal wells,increasingly importance has been attached to horizontal well formation evaluation.The horizontal well logging series in this country are simple,which make formation evaluation of horizontal well more difficult.This paper presented an effective method of horizontal well formation evaluation based on the combination of acoustic and resistivity logging.This paper systematically analyzed the horizontal well logging response characteristics and the influencing factors,especially borehole and surrounding rock on natural gamma rag log,borehole and anisotropy on acoustic log,borehole,anisotropy and surrounding rock on the lateral and induction log.On the basis of comparison the differences of vertical wells and horizontal well logging response characteristic,this paper established horizontal well stratigraphic model.Calculate the gamma ray curve using the fast forward modeling algorithm,then compared whit the measured curve and modify the model repeatedly,a complete stratigraphic model can be achieved.The key to horizontal well formation evaluation is to compare with vertical well.Logging response characteristics in horizontal wells are quite different with vertical wells because of the effect on formation anisotropy.Conventional interpretation models in vertical well cannot be directly used in horizontal well formation evaluation.Logging curves in horizontal well must be corrected before we use the logging interpretation model established in vertical wells.Rock physics experiments and statistical translation method are used for horizontal well acoustic time curve correction,and the correction of resistivity curve in horizontal well can be done by using petrophysics experiment,statistical translation and resistivity reconstruction method.As for the reservoir parameter calculation in horizontal well,based on the corrected logging data and formation evaluation model established in vertical wells researchers can calculate the reservoir parameters and identify reservoir fluid property.Benefiting from the workflow the accuracy of the horizontal well log interpretation was improved greatly.Using integrated physical parameters,oil saturation and shale content the horizontal wells segment classification evaluation index was built.Because of the limitation of logging tool’s detection depth,formation far from tools cannot be measured.Take into account changes in oil layer thickness,the comprehensive index can be used to subdivide the horizontal section into three categories reservoir,which provides information for fracturing and production.