深层高压低渗砂岩油藏储层微观孔喉特征:以东濮凹陷文东油田沙三中段油藏为例

为深入探讨深层高压低渗透砂岩油藏储层微观孔喉特征,开展了岩心样品的恒速压汞测试。结果表明,储层孔道大小及分布性质差异不大,孔隙半径呈正态分布,主峰分布在100～300μm;喉道半径是控制储层性质的主要因素,渗透率与喉道半径的相关性好于其与孔隙半径的相关性。储层有效喉道半径、有效孔隙半径、有效喉道体积、有效孔隙体积、有效孔喉半径比等孔喉特征参数与物性参数具有较好的相关关系。高渗透率岩样的有效孔喉半径比较低,且有效孔喉半径比分布频率较高。渗透性越好,孔喉半径比越低,且其分布越集中。分析认为,恒速压汞的孔喉特征参数中排驱压力(pT)、中值压力(pc50)、最大进汞饱和度(SHgmax)小于常规压汞的,最大连通孔喉半径(Rmax)、中值半径(r50)大于常规压汞的。相对于常规压汞,恒速压汞获得的孔喉特征参数更准确。

Characteristics of Micro-pore Throat in High Pressure and Low-Permeability Sandstone Reservoir of Deep Section:Taking the Middle of the Third Member of Shahejie Formation in Wendong Oilfield, Dongpu Sag as an Example

The features of micro-pore throat in high pressure and low-permeability sandstone reservoir of deep section were analyzed by using the constant-rate mercury injection technology.The research shows there are little difference in the pore’s sizes and distribution,the pore radius is unimodal distribution,and the main peak is from 100 μm to 300 μm.Throat radius is the main factor that controls the reservoir property.The relation between the permeability and the throat radius is better than that between it and the pore radius.There is better correlation between the reservoir property and the pore throat parameters such as the effective throat radius,pore radius,throat volume,pore volume,and pore-to-throat radius ratio.When it comes to the high permeability sandstone sample,the effective pore-to-throat radius ratio is low,and its distribution frequency is high.The better the permeability is,the lower the pore-to-throat radius ratio is,and the more concentrated the distribution of the pore-to-throat radius ratio is.It’s analyzed that in the pore throat parameters of the constant-rate mercury injection,the numerical values such as the displacement pressure(pT),the median pressure(pc50),and the largest injection mercury saturation(SHgmax) are lower than that of the conventional mercury injection,and the largest continuous throat radius(Rmax),the median radius(r50) are larger than that of the conventional mercury injection.Compared with the conventional mercury injection,the pore throat feature parameters from the constant-rate mercury injection are more accurate.