低孔低渗构造岩性油藏油水倒置成因研究

Oil/Water Inversion and Its Genetic Mechanism in the Structural-Lithologic Reservoir of Low-Porosity and Low Permeability

为了厘清冀中坳陷饶阳凹陷蠡县斜坡西柳10井区油水倒置的现象,以蠡县斜坡西柳10断块高43井区的岩心描述与物性分析为基础,通过核磁共振等方法,结合单井、连井砂体的精细对比,建立了3种油水倒置的单井成因模式和2种砂体对比模式.用这些模式将西柳10断块高43井区沙三段顶部砂组重新进行分层对比.研究表明:西柳10井区储层孔隙度一般在10%～15%,渗透率为1.56～14.85×10-3μm3,属低孔低渗储层,且层内频繁发育的泥岩隔夹层增加了储层的非均质性.驱替动力弱、储层物性差和非均质性强是造成该区域出现油水倒置现象的主要因素.驱替动力弱导致油水置换不充分,储层物性差使得油气充注程度低,形成了低饱和度油藏,同时较发育的隔夹层使得油水关系更为复杂,直接引起低孔低渗油藏出现油水倒置.

In order to understand the phenomenon of oil/water inversion in Xiliu-10 oil field in Lixian slope,Raoyang sag,Jizhong subbasin,based on core description and physical property analysis using a nuclear magnetic resonance（NMR）,and combined with detailed analysis on correlation of single wells and connected wells sand bodies,three kinds of genetic models of oil/water inversion of single well and two kinds of sandbody correlation models were proposed.The layers in the upper 3rd formation of Shahejie group were re-subdivided and re-correlated.The results show that the porosity of Xiliu-10 is normally 10%-15%,and the permeability is 1.56-14.85×10^-3 μm3,which indicate a low porosity and permeability reservoir.The reservoir heterogeneity is worsened by frequent intersected mudstone.Low displacing force,bad reservoir quality and strong heterogeneity are the main factors which contribute to the oil/water inversion.Low displacing force resulted in inadequate oil and water displacement,and bad reservoir physical property leaded to low hydrocarbon charging degree and thus low saturation reservoirs are formed.The frequent mudstone interlayers made oil-water relationship more complicated and directly leaded to the oil/water inversion of reservoir with low porosity and low permeability.