注聚井用油层保护剂研究及应用

大庆聚合物驱油田20％以上注入井的注入压力已接近或达到油藏破裂压力，压裂或化学解堵改善注入性能的有效期很短。报道了一种注聚油层保护剂的作用机理、室内性能考察及现场应用效果。该剂的作用机理如下：阳离子表面活性剂优先于HPAM在岩石上吸附，吸附层造成疏水环境，吸附层增溶有机酸、醇，形成超薄膜，改变岩石表面性质，稳定剂螯合、屏蔽高价阳离子，减少或防止HPAM吸附、滞留、沉淀造成的堵塞。在室内实验中该剂使HPAM在储层岩屑上的静态吸附量由10．01mg／g减少至0．624mg／g；注入30PV该剂溶液使储层岩心渗透率下降30％，再注入60PV聚合物溶液则下降56．2％，而只注入60PV聚合物溶液则下降75．8％；注入60PV聚合物溶液使3支储层岩心渗透率下降75、0％～79．2％，再注入30PV该剂溶液使渗透率恢复至原值的54．5％～58．3％。4口注聚井先进行化学解堵再注入油层保护剂溶液，注入压力平均下降1．75MVa，有效期超过6～10个月。图2表2参2。

A Reservoir Treating/Protecting Agent for Use In Polymer Injection Wells in Daqing

In the areas of Daqing where polymer flood programs are being performed, the injection pressure of >20% polymer injection wells approaches or reaches the fracturing pressure of the reservoir formations.Hydrofracturing or chemical blockage relieving operations for improving well injectivity in such wells are effective only shortly. The functioning mechanisms, the performance properties, and the results of field uses of a reservoir treating/protecting agent(RTRA)are presented. The functioning mechanisms involved can be described as follows: the cationic surfactant(s) adsorb onto reservoir rocks prior to HPAM; hydrophobic zones are created at the adsorbed layers which solubilize the organic acid(s) and alcohol(s) to form super film and thus alterate rock surface properties; the stabilizing substances chelate and screen polyvalent inorganic cations; as a results of all these functions the blockages caused by adsorbed, retended and precipitated HPAM molecules are relieved and removed. In laboratory experiments, the static adsorption of an HPAM from solution on rock cuttings decreases from 10.01 mg/g to 0.624 mg/g at the presence of RTRA; the aqueous phase permeability of reservoir cores decreases by 30.0% after 30 PV of RTRA solution injected and by 56.2% after 60 PV of HPAM solution injected additionally in comparison with 75.8% after 60 PV of HPAM solution injected alone; the permeability of 3 reservoir cores is decreased by 75.0-79.2% after 60 PV of HPAM solution injected and recovered to 54.5-58.3% of initial values after 30 PV of RTRA solution injected additionally. The polymer injection pressure of 4 wells decreases by 1.75 MPa in avevage and the improvement in injectivity is observed in more than 6-10 months after a chemical blockage relieving operation performed and followed by RTRA solution injection.