中东叙利亚A油田碳酸盐岩油藏低阻成因分析

Genesis of Low Resistivity Limestone Reservoirs in Oilfield A of Syria

中东叙利亚A油田J组是世界范围内罕见的低阻碳酸盐岩油藏,基质储层高孔低渗,油层电阻率仅有0.5～5.0?·m,甚至小于水层电阻率。前人对该地区储层低阻成因的研究较少,为了正确评价油藏,开展了J组油层低阻成因机理和主控因素分析。研究发现,A油田地质背景的特殊性是形成碳酸盐岩低阻油层岩石物理成因的基础,岩石物理成因揭示了碳酸盐岩油层低阻的本质。低幅度构造、弱水动力沉积是形成低阻油层的地质背景,高束缚水饱和度、高地层水矿化度、黏土附加导电作用以及导电矿物是形成低阻油层的内因。因此,J组碳酸盐岩低阻油层的形成是宏观地质背景和微观岩石物理特征共同作用的结果。

J Formation in Oilfield A of Syria is a rare low resistance limestone reservoir in the world,with high porosity,low permeable matrix reservoir and with resistance of 0.5～5.0 Ω·m lower than water layer. Because few studies have been made on the causes for this low resistance reservoir before,to correctly evaluate the reservoir,this paper analyzes the forming mechanism and dominating factors of low resistance carbon ate oil formation. We found that the special geological background is the basic of petrophysical origin in low-resistivity oil formation. The petrophysical origin uncovers the essence low-resistivity in carbonate oil formation. Low amplitude structures and weak hydrodynamic sediment are the geological background of low resistivity oil formation. High irreducible water saturation,high formation water salinity,additive conductivity of clay minerals and conductive mineral are the internal causes for low-resistivity oil formation. The formation of low-resistivity reservoirs in carbonate rock is the result of macroscopic geological background and microscopic petrophysics characteristics.