南八仙油气田电阻率时间推移测井响应特征及侵入规律研究

On Resistivity Time-lapse Logging Responses and Mud Invasion Law in Nabaxian Oil-gas Field.

南八仙油气田为轻质油气层 ,泥浆侵入影响很大。泥浆侵入深度与泥饼形成过程中泥浆滤液渗入地层的数量有关 ;泥浆滤液的渗入量与泥浆特性有关 ,也与泥浆柱压力和地层压力之差及钻井后至测井时的时间间隔有关。当泥浆矿化度低于地层水矿化度时 ,油气层与水层的径向侵入剖面电性有明显差别 ,各种测井响应都有相应的特征。利用时间推移测井找出泥浆浸泡时间对油气层双感应、双侧向测井浸入规律 ,为准确确定含油饱和度、减小泥浆侵入的影响有着很重要的作用。

Nabaxian Oilfield is a light crude oilfield where the effect of mud invasion on reservoir is very serious. The invasion depth has something to do with the quantity of mud filtrate invading into formation in the course of mud cake buildup. And the quantity is not only related to mud property, but also to the difference between mud column pressure and formation pressure as well as the interval time from drillout to logging. When the mud salinity is lower than that of formation water, resistivity of radial invasion profile in oil-gas zone and water zone is obviously different from each other. Since every kind of logging response has its own intrinsic feature, so it can be used to summarize its regularity of changes to determine the log interpretation method for oil-gas zones. The effect of mud invasion into formation and mud soak time in formation on the dual laterolog and dual induction log can be known through time-lapse logging, which is important to determine oil saturation exactly and reduce the mud invasion influence.