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大庆外围已发现的 2 0个低渗透或分散小油田 ,储层品质差 ,在开发中易受伤害 ,伤害后难恢复。以储量相对较大的两个典型大庆外围油田为例 ,实验测定了油层岩心的岩相学特征和敏感性程度。龙西油田高台子油层岩性以含泥粉砂岩为主 ,泥质含量 7.2 %～ 38.7% ;粘土矿物组成复杂 ,以伊利石为主 (6 5 %～ 85 % ) ;最大孔隙半径 4.74μm2 ,中值半径 0 .0 0 4～ 0 .2 95 μm2 ,孔隙和喉道半径相差悬殊 ;渗透率特低 ,地层水测渗透率为 0 .0 13× 10 -3 ～ 13×10 -3 μm2 ;敏感性程度和相应敏感指数如下 :弱速敏 ,Iv=0 .0 4～ 0 .35 ;中等偏弱到强水敏 ,Iw=0 .31～ 0 .78;中等盐敏 ,Is=0 .39～ 0 .6 0 ,临界矿化度 2 2 5 0mg/L ;中等酸敏 ,Ia=0 .41～ 0 .47。葡萄花油田葡萄花油层岩性为细粒、粉粒砂岩 ,泥质含量 10 %～ 15 % ;不同深度上粘土含量不同 ,组成复杂 ,可能发生地层微粒运移 ;最大孔隙半径 13.7μm ,中值半径 1.9～ 5 .2 μm ,有厚约 8m的疏松岩层 ;地层水测渗透率 2 1× 10 -3 ～ 2 93× 10 -3 μm2 ;敏感性程度和相应敏感指数如下 :弱速敏 ,Iv=0 .0 6～ 0 .2 7;中等偏弱到中等偏强水敏 ,Iw=0 .31～ 0 .78;弱到中等盐敏 ,Is=9.5 9～5 7.0 6 ,临界矿化度 6 0 71mg/L ;中等酸敏 ,Ia=0 .31～ 0 .39。两
20 low-permeability or dispersed small oil fields discovered in the periphery of Daqing have poor reservoir quality and are vulnerable to development and difficult to recover after injury. Taking the two typical Daqing peripheral oilfields with relatively large reserves as an example, the lithofacies characteristics and sensitivity of the oil core are experimentally determined. The lithology of Gaotaizi oil layer in Longxi Oilfield is dominated by silt-bearing siltstones, with a shale content of 7.2% ~ 38.7%. The clay minerals are mainly composed of illites (65% ~ 85%), the maximum pore radius is 4.74μm2, The median radius is 0.040 ~ 2.095 μm 2, and the difference between the pore radius and the throat radius is very poor. The permeability is extremely low, and permeability of formation water is 0.013 × 10 -3 ~ 13 × 10 -3 μm 2. Sensitivity and the corresponding sensitive index are as follows: Weak speed sensitive, Iv = 0. 04 ~ 0.35; moderate to strong water sensitive, Iw = 0.31 ~ 0.78; moderate salt sensitivity, Is = 0. 39 ~ 0. 60, critical salinity 225 mg / L; moderate acid sensitivity, Ia = 0 .41 ~ 0.47. The Putaohua oil layer in Putaohua oilfield is composed of fine-grained and silt-sandstone with a shale content of 10% -15%. Different clay contents and compositions are complex at different depths, and migration of formation particles may occur. The maximum pore radius is 13.7μm, With a radius of 1.9-5.2 μm and a thickness of about 8 m. The permeability of formation water is measured from 2 × 10 -3 to 2 × 10 -3 μm 2. The sensitivity and the corresponding sensitivity index are as follows: Weak speed sensitive, Iv = 0. 0 6 ~ 0. 2 7; moderate to moderately strong water sensitivity, Iw = 0.31 ~ 0.78; weak to moderate salt sensitivity, Is = 9.5 9 ~ 5 7.0 6, the critical salinity 6 0 71mg / L; moderately acid sensitive, Ia = 0.31 ~ 0.39. Two