Research On Logging Evaluation Technology Of Low Saturation Oil Formation In Yaojia Formation West Of Changyuan,Daqing Oilfield

The domestic low-porosity and low-permeability oil layers are mainly in the Cretaceous in the Songliao Basin,the Cretaceous,Jurassic and Paleozoic in the northwest region and the deep Paleogene strata in the Bohai Bay.The oil saturation of low-saturation oil reservoirs is relatively low,and the genesis of low-saturation oil reservoirs in different blocks of different oilfields is very different,and the geological background of such reservoirs is quite complex,and the genetic mechanism is affected by various factors.The first step in the evaluation of saturation interpretation is to analyze the geological origin.The resistivity curves of the oil-water layer and the water layer of the Sartu oil layer and Putaohua oil layer in the west of Changyuan,Daqing are not well differentiated,and the response characteristics of the resistivity curve are complicated by the content of calcium and mud.It is a typical low-saturation reservoir,and it is difficult to identify reservoir parameters and fluids.Based on the response characteristics of logging curves and the analysis of core experiments,this paper clarifies that the main causes of low saturation oil reservoirs in the study area are the following three points: 1)low saturation caused by additional conductivity of clay minerals;2)high immobilized water saturation caused by 3)Low saturation caused by thin interbedded sand and mudstone.By analyzing the logging data of the 0.2-meter thin layer logging new technology,it is clarified that the thin layer logging series has the advantages of identifying thin layers and distinguishing oil and water layers compared with other conventional logging data,which significantly improves the interpretation accuracy of thin layer logging;application The core calibration logging method is used to establish the parameter model of reservoir shale content,calcium content,effective porosity and permeability.Based on the analysis data of whole-rock X-ray diffraction,nuclear magnetic resonance and mercury injection experiments,the three-porosity logging calculation method of clay water porosity,microcapillary water porosity and free fluid porosity was determined,and based on this,a three-water porosity suitable for the study area was established.The original saturation calculation model.Based on the four main factors controlling the productivity of lowsaturation reservoirs,the "quartile method",which is divided into regions,formations,pore types,and reservoir thicknesses,has obvious advantages in identifying the fluid properties of low-saturation reservoirs in the study area.Oil and water identification,the identification accuracy is high,reaching more than 92.9%.The practical application shows that the method presented in this paper is suitable for the low saturation oil layers of Longxi and Xingxi in the west of Changyuan,Daqing,and the low-saturation oil layers in Putaohua,which significantly improves the interpretation accuracy.