Investigation On Logging Interpretation Method For Watered-out Zone In F Oilfield

As the development of oilfield by water flooding is prolonged, the differences of the reservoir increase on the aspects of original lithological, electrical, physical and oil-containing properties. And the long-term fracturing exploitation complicate the geographical circumstances, which make it is difficult to calculate the residual oil saturation by log interpretation.In this thesis, for providing rational watered-out level and improving the coincidence rate of log interpretation in watered-out formation, the changes of geological characteristics in watered-out formation on the aspects of oil-containing property, oil-water distribution, formation water salinity, clay mineral microstructure, reservoir physical property and wettability are analyzed, and the changes of physical characteristics of logging in watered-out formation and the influence factors are analyzed, too. The interpretation models of porosity, permeability, saturation and water production ratio of the watered-out formation are established by using the core data. The qualitative and quantitative interpretation methods are put forward to evaluate the watered-out formation, and to divide the watered-out level. The single-well multi-parameter processing software is developed on the platform of FORWARD, through which the parameters of saturation, porosity, permeability, shale content, oil displacement efficiency, water cut and residual oil saturation, etc. can be calculated. More than 700 watered-out wells in F oilfield are interpreted by using the spontaneous potential changes before and after watered-out, the comprehensive electrical resistivity comparative method and the presented five-level interpretation standard. The overall coincidence rate is 81.3%, increases 3.5% comparing with the value of 77.8% in last year. The result obtained from the processing on Jian23 well indicates that the calculated values of saturation, irreducible water saturation, porosity match fairly well with the tested values from the core from the same well. The water cut and the oil displacement efficiency are waiting to be examined after the well being put into production.