古潜山致密砂岩水平井钻完井技术

Drilling and Completion Technology for Buried-hill Tight Sandstone Horizontal Wells

致密砂岩孔渗性低,可钻性差,长水平段水平井钻井难度大。以任丘古潜山致密砂岩第一口水平预探井任密1H井为例,对长水平段水平井钻完井施工中的难点及相应技术措施进行了论述。任密1H井钻进过程中摩阻扭矩大,井眼轨迹不易控制;岩屑上返路程长,易形成岩屑床;要求全井封固,固井难度大。通过钻具组合和钻头优选,应用"螺杆+MWD"定向控制的井眼轨迹控制钻井技术保证了井身质量。应用钻井液技术控制高温、高压滤失量,降低钻井液摩阻系数,保证岩屑悬浮和携带,确保井眼清洁。应用低失水、低敏感性及稳定性好的大温差双密度水泥浆体系配套固井技术有效保证了固井质量。整套钻完井技术保证该水平井中靶率为100%,全井段封固合格率为100%,实现了该区致密储层油气勘探突破。对国内其他地区古潜山致密砂岩水平井的施工有一定的借鉴意义。

Tight sandstone features in low porosity and permeability and poor drillability, so it is difficult to drill horizontal wells of long horizontal segment. Taking Well Rental 1H, the first exploratory horizontal well in Renqiu buried-hill tight sandstone as an example, we discussed the difficulties and relevant countermeasures for horizontal well drilling and comple- tion of long horizontal segment. During drilling, it produced great friction torque, and it was difficult to control the well bore trajectory. What＇ s more, there were another two difficulties when drilling the well, one was the long distance of the cuttings back to the wellhead, and the other was the easily formed cuttings bed. And it was required to cement all wellbore. Through drilling assembly and bit optimization, we applied the borehole trajectory control technology of ＂screw＋MWD＂ oriented control to assure wellbore quality. In addition, we used drilling fluid technology to control filtration of high temperature and high pressure, to reduce filtration coefficient of drilling fluid, and to ensure cuttings suspension and carrying as well as cleanliness of borehole. And the cementing quality was guaranteed, with the cementing technology matching with cement slurry system of large temperature difference, double density, low water loss, low sensitivity, and good stability. With the systematic drilling and completion technology, both of the target rate and the seal qualification rate of the horizontal well were 100%, and breakthrough was made in exploration for oil and gas in tight reservoirs of the area. This could be a reference for buried-hill tight sandstone horizontal well drilling in other areas of China.