柳林煤层气储层敏感性评价实验

Sensitivity evaluation experiment of Liulin CBM reservoir

为实现柳林地区煤层气的合理高效开采,对该区主力煤层气储层进行了煤岩流速敏感性、水敏性、碱敏性和酸敏性实验评价。实验结果表明：柳林山西组煤样速敏损害程度中等偏弱至偏强,临界流速低;水敏损害程度为无水敏至中等偏强;碱敏损害程度为中等偏弱至强碱敏,临界pH值为7。此外,煤样的碱敏损害程度与其吸附氢氧根离子量具有正相关性;煤样盐酸酸敏指数为？2.546~0.004 5,无酸敏性。由此建议：煤层气排采初期,应控制排采速度在2 m/d之下以实现平稳降液;压裂液配方中应采用1%~2%的KCl作为防膨剂;入井液的pH值应控制在7以下。

To make the exploitation of Liulin CBM reasonable and efficient, the flow velocity sensitivity, water sensitivity, alkaline sensitivity and acid sensitivity of Liulin coal samples were tested and evaluated. The results show that Shanxi coal＇s velocity sensitivity extent is from medium weak to medium strong and the critical flow velocity is low; The damage caused by water sensitivity is from non to medium strong; The damage caused by alkaline sensitivity is from medium weak to strong and the value of critical pH is 7. In addition, the damage caused by alkaline sensitivity of coal positively relates with the number of adsorbed hydroxide; The hydrochloric acid sensitivity index is -2.546 to 0.004 5, and no acid sensitivity. To sum up, the fluid velocity of fall should be controlled below 2 m/d to achieve a smooth pressure reduction at the beginning of CBM exploitation; 1%-2% KC1 is used as clay stabilizer; the pH of operation fluid should be kept below 7.