克深243井盐膏层大尺寸套管固井技术

克深243井是部署在新疆拜城县的一口评价井，三开钻进至库姆格列木群盐岩段中途完钻，井深5532 m，井底静止温度127.6℃，钻井液密度2.43 g/cm3，地层压力为132 MPa，下入φ273.05 mm+φ293.45 mm复合大尺寸套管进行双级固井。固井存在地层承压能力低井段易漏、盐膏层蠕变、水泥浆压稳防窜性能要求高、长封固段顶部强度发展缓慢等难题，通过选用微锰与GM-1加重剂共同干混保证水泥浆密度，选用2种防窜剂提高水泥浆防窜性能，将高温降失水剂和低温降失水剂复配使用，降低缓凝剂的加量，避免大温差下顶部水泥浆出现超缓凝，加以配套的固井工艺措施，该井段固井施工顺利，固井质量合格。 

Cementing of Large-sized Casing through Salt and Gypsum Interbeds in Well Keshen-243

Keshen-243 is an appraisal well located 29 km to Baicheng County, Xinjiang. The 3rd interval of this well was drilled to 5,532 m, and two-stage cementing was to be conducted to cement the hole penetrating Kumugeliemu group (salt rocks). Bottom hole static temperature of the 3rd interval was 127.6℃, mud weight was 2.43 g/cm3, and the maximum formation pressure was 132 MPa. Casing strings of φ273.05 mm + φ293.45 mm in diameter were to be run into the hole and cemented. Several problems were expected during casing running, such as low pressure bearing of the formations to be cemented which may result in lost circulation, creeping of the salt/gypsum interbeds, channeling of cement slurry and slow setting of the top cement slurry when cementing long open hole section etc. In formulating the cement slurry to address these problems, a micro powder manganese mineral and another weighting agent GM-1 were dry mixed together into the cement slurry to ensure its density, two anti-channeling agents used to improve the anti-channeling performance of the cement slurry, and a combination of high temperature and low temperature filtrate loss reducers to improve the filtration property of the cement slurry. The amount of cement retarder was reduced to avoid long retarding period of the top cement slurry under the circumstance of big temperature differences. All these selected additives, plus the cementing techniques engineered, made the two-stage cementing operation through salt-gypsum interbedded formations smoothly done even when there was lost circulation flowed by mud kick. The cementing job was qualified.