孤东油田馆陶组下段低阻油层类型及成因分析

Types of Low Resistivity Layer and Genesis Analysis of the Lower Interval of Guantao Formation in Gudong Oil-field

孤东油田馆陶组下段是物性总体较好的河流相储层,电阻率显示比馆上段低很多,长期以来认为储层含油性较差。经过重新解释和试采发现部分储层井段为高产低阻油层。通过对研究区低阻油层成因分析,认为造成孤东油田馆下段油层低阻的原因主要有地层水矿化度高、油藏构造幅度小、储层束缚水饱和度高等。根据低阻油层的低阻成因和油层地质特征,把低阻油层分为低渗型、高渗型、薄层型三类,并分析了造成这三类油层低阻的主要原因。本项研究对孤东油田低阻油层的解释提供了基础,为老区寻找储量提供了新的方向。

Lower interval of the Guantao Formation, a fluvial reservoir with overall good physical properties, has long been thought to have poor oil - bearing properties as the resistivity is much lower than the upper interval. Reinter-pretation and production test reveal that part of the reservoir is highly productive oil layers with low resistivity. Based on genesis analysis of the low resistivity layers in the interest area, it is believed that the low resistivity in the lower interval are mainly caused by high salinity, small amplitude of structure and high irreducible water saturation. The low resistivity layers are divided into low permeability type, high permeability type and thin layer type according to the genesis and geological features. The study achievements provide a basis for interpretation of the low resistivity layers in Gudong oilfield and new methods for adding reserves to mature blocks.