长庆油田水基环保成膜钻井液研究与现场试验

长庆油田的地理气候条件独特，要求该油田所用钻井液应具有无毒、易降解和环境可接受性好的特点，为此，以多糖衍生物G312为主剂，通过优选其他添加剂，形成了适合于长庆油田低压、低渗、低孔储层的水基环保成膜钻井液。该钻井液利用多糖衍生物的半透膜作用和有机胺独特的抑制防塌作用，达到了既能保护储层又能保护环境的目的，与传统的烷基葡萄糖甙钻井液相比，具有防塌性能好、主处理剂加量少、抗温抗盐能力强的优点。室内性能评价结果表明:水基环保成膜钻井液无生物毒性，重金属含量等达到了污水排放标准要求；由于具有半透膜效应，该钻井液抑制性较强，岩屑在其中的线性膨胀率与在清水中相比降低了35.6%，岩屑一次回收率达到94.80%、二次回收率达到89.34%；耐温性较好，可耐120℃高温，综合性能优良。水基环保成膜钻井液在长庆油田苏里格地区A井进行了现场试验，钻井过程中没有发生井下故障，井径规则，电测、下套管作业一次到底，且钻井液的环保性能指标达到了污水排放标准。研究结果表明，水基环保成膜钻井液的环保性能和其他性能均能满足长庆油田的要求。 

Research and Field Test of Water-Based Environmental-Friendly Membrane Forming Drilling Fluid Technology in Changqing Oilfield

Based on the geographic climate condition of Changqing Oilfield,drilling fluid used in this oil and gas field should exhibit non-toxicity,easy degradation and good environmental acceptability.Thus,water-based environmental friendly membrane forming drilling fluid was created that is suitable for low-pressure,low-permeability and low-porosity reservoir.It was synthesizedby taking polysaccharide derivative G312 as main agent and by optimizing other additives. This drilling fluid achieved the stated objective of protecting reservoirs and the environment through the semi-permeable membrane effect of polysaccharide derivatives and a distinctive sloughing control of organic amine. Compared with traditional alkylglucoside drilling fluid,this drilling fluid possesses the advantage of having good anti-collapse performance,requiring less dosage of main treatment additives and having a strong temperature and salt resistance ability.Laboratory performance evaluation results showed that water-based environmental-friendly membrane forming drilling fluid had no biotoxicity and its heavy metal content and other indicators met the standard wastewater discharge requirements.Due to its semi-permeable membrane effect,it had strong inhibition.The linear expansion ratio of cuttings in this drilling fluid was 35.6% lower than that in clear water.The primary recovery of cuttings reached 94.80% and secondary recovery rate reached 89.34%.Moreover,this drilling fluid had good temperature resistance of 120℃ and excellent comprehensive properties.In the trial use of water-based environmental-friendly membrane forming drilling fluid while drilling well A of Sulige area in Changqing Oilfield,no downhole failure and the well diameter was regular.Electric logging and operations for running casing were successful on first run.Besides,environmental protection property indices of the drilling fluid satisfied wastewater discharge standard.Therefore,the study indicated that the environmental-friendly properties and other properties of water-based environmental-friendly membrane forming drilling fluid could meet all requirements of Changqing Oilfield.