渤海湾埕海新区水平井固井配套油气层保护技术

渤海湾埕海新区沙河街组砂体是已探明的浅层稠油油藏，计划钻8口水平井，采用筛管完井，φ244.5 mm技术套管水平段已进入沙河街组储层。在前期勘探井作业过程中，高孔-高渗砂岩层漏失、水泥浆滤液渗透及套管偏心边底水窜流对储层污染严重。为保护油气层，优选应用密度1.50 g/cm3的纳米基低密度低失水水泥浆，游离液和密度差为0，水泥石24 h强度不小于17.9 MPa，失水量不大于38 mL，高于标准要求24%以上。优选应用φ244.5 mm新型一体式弹性扶正器，无应力薄弱点，较普通扶正器其复位力增加25%，起动力降低27%，使套管居中度提高57%以上。综合形成了适合埕海新区水平井固井的配套油气层保护技术，现场应用6口井，固井未发生漏失、水层窜流，固井质量优质，并获高产油流，有利于该区域油气资源的进一步生产开发。 

Reservoir Protection Technology Used in Cementing Horizontal Wells in Chenghai Xinqu,Bohai Bay

The Shahejie Formation sandstone is a proven shallow heavy oil reservoir located in the Chenghai Xinqu area, Bohai Bay. Eight horizontal wells have been planned to drill in this area and completed with screen pipes. The φ244.5 mm technical casing is used to case the horizontal section drilled into the Shahejie Formation. In early stage exploration, the sandstone reservoir was highly contaminated because of mud losses into the high porosity high permeability sandstone, invasion of cement slurry filtrates, and edgebottom water channeling caused by casing string eccentricity. To protect the reservoir from damaging, a low-density low filter loss nanoparticle cement slurry of 1.5 g/cm3 was used to cement the well. The cement slurry had no free water and no density difference between the top and the bottom. The strength of the set cement was at least 17.9 MPa after aging for 24 hours, and the filter loss of the cement slurry was 38 mL at most. These two parameters are 24% better than standard requirements for cement slurry. A new type of φ244.5 mm all-in-one elastic centralizer was used with casing. This all-in-one elastic centralizer has no stress weak point, and compared with conventional centralizers, this new type of centralizer has restoring force that is 25% higher, starting force that is 27% lower, the centrality of the casing string can be enhanced by at least 57%. These technologies have been proved suitable for use in cementing horizontal wells drilled in Chenghai Xinqu. Six wells have been cemented with these technologies and no slurry losses and water channeling have occurred during well cementing. High quality cement job and high oil production rate were obtained. These technologies are beneficial to the development of oil and gas resources in Chenghai Xinqu area.