顺北油气田非均质碳酸盐岩储层矿化度敏感规律

顺北油气田受断裂多期活动的影响产生了大量的裂缝储集体，具有缝洞型碳酸盐岩特征。针对顺北油气田碳酸盐岩储层的矿化度敏感性评价可知，多个样品数据难以形成统一结论，无法有效指导现场生产。X射线全岩矿物测定一间房组、鹰山组储层垂直方向方解石、白云石、硅质、黏土矿物总含量波动范围在0.9%～65%。扫描电镜观察片状伊蒙混层集中充填裂缝，裂缝数量及形态随机性分布。氦气与氮气法测定2套储层垂直方向的孔隙度为0.42%～2.40%、渗透率为0.03～7.62 mD，波动明显且总孔隙空间较小。测定一间房组水敏、盐敏渗透率损害率为29.47%～74.80%、30.44%～82.93%；鹰山组水敏、盐敏渗透率损害率为66.06%～74.80%、78.10%～79.91%，矿物组分与裂缝发育非均质导致不同区域矿化度敏感性显著波动。用数学方法建立了渗透率损失率、无敏感矿化度范围与黏土矿物总含量比、孔隙度、渗透率、地层水矿化度等因素间定量数学关系，提高储层矿化度敏感评价全面性和快速性，计算临界矿化度KCl溶液较传统方法污染储层渗透率降幅缩小了19.90%，提高矿化度敏感控制效果明显。

Patterns of Salinity Sensitivity of Heterogeneous Carbonate Reservoirs in Shunbei Oil and Gas Field

Large amount of fracture reservoirs are produced in Shunbei oil and gas field because of the effects of the multi stage movement of faults, rendering the reservoirs characteristics of fractured vuggy carbonate. Evaluation of the salinity sensitivity of carbonate reservoirs in Shunbei showed that a unified conclusion cannot achieved with data of many samples, and is thus unable to guide field production. Whole mineral content measurement with XRD showed that the total content of minerals (including calcite, dolomite, silica and clay) along the vertical direction of the Yijianfang formation and the Yingshan formation reservoirs changes between 0.9% and 65%. SEM observation showed that the formation fractures are filled with plate-like illite-smectite mixed layers, and the quantity and shape of the fractures are randomly distributed. The vertical porosity and permeability of 2 sets of reservoir rock samples measured with helium and nitrogen are 0.42%-2.40% and 0.03-7.62 mD, respectively, indicating obvious fluctuation in the distribution of porosity and permeability, and small total porosity. Permeability impairment by water sensitivity and salt sensitivity of the Yijianfang formation rocks is 29.47%-74.80% and 30.44-82.93%, respectively, and for the Yingshan formation rocks, the data are 66.06%-75.80% and 78.10%-79.91%, respectively, indicating that mineral components and fracture development resulted in obvious fluctuation in salinity sensitivity in different areas. A mathematical model was developed to quantitatively describe the relationship among several factors, such as ratio of permeability loss, salinity range in which formation porosity and permeability are not impaired, total content of clay minerals, porosity, permeability and salinity of formation water. The mathematical model can be used to evaluate the salinity sensitivity of reservoir rocks with comprehensiveness and rapidity. Compared with conventional methods, the percent reduction of permeability of contaminated reservoir was reduced by 19.90% using the critical concentration of KCl calculated with this model, an obvious controlling effect of increasing salinity sensitivity.