【作者】 杨志毅；

【导师】 邓建民； 蒋宗野；

【作者基本信息】 西南石油学院 ， 油气井工程， 2003， 硕士

【摘要】 本论文对低压易漏、易窜井的固井技术进行了较为系统的研究。 针对低压易漏、易窜井的特点，提出了采取膨胀与触变相结合从而实现低密度水泥防窜的方法，该方法通过加防窜剂增加水泥浆孔隙压力、并赋予水泥浆以良好的触变性，可使水泥浆具有较强的防窜能力。通过分析，优选了外掺料与外加剂；通过大量的实验研究，研制出了新型的膨胀、触变型低密度防窜水泥浆体系。该体系具有沉降稳定性好、触变性强、低温早强、防窜能力较强、零析水、低失水、稠化时间可调的特点。针对新疆陆梁油田陆9井区，研制出了综合工程性能良好的密度为1.50g／cm~3与1.30g／cm~3的二种水泥浆，实验分析了地层水对水泥石强度发展的影响。 分析了低压易漏井注水泥防漏的主要途径，对于低压易漏(包括易窜)井注水泥，提出了平衡压力连续变排量顶替的方法，该方法既可以实现平衡压力注水泥，又可以缩短施工时间，进而缩短所要求的水泥浆稠化时间，从而有利于防窜和水泥石强度的发展。归纳给出了低压易漏井平衡压力注水泥设计的步骤。针对陆9井区各种不同形式的固井，进行了平衡压力注水泥设计。 给出并讨论了低压易漏井提高注水泥顶替效率的工艺技术措施。通过分析，明确提出对于低压易漏井注水泥，可以采取 钻井液密度＞前置液密度＜水泥浆密度 钻井液粘度＞前置液粘度＜水泥浆粘度的浆柱结构，这其中要求前置液为紊流。该浆柱结构利用前置液紊流的冲蚀、扰动作用实现对钻井液的顶替，利用水泥浆与前置液之间的密度差与粘度差实现对前置液的顶替，最终获得高的环空顶替效率。 通过研究与应用，形成了一套完整的适合低压易漏、易窜井固井的综合配套技术。在新疆陆梁油田陆9井区，成功地进行了382口井共440井次的现场试验与推广应用，获得了总固井合格率达97.7％、总固井优质率达70.0％、油层套管固井优质率达77.0％的良好效果，解决了陆9井区固井低压易漏、易窜的技术难题，保证了陆9井区的开发。本研究的成果对于其它低压易漏、易窜井的固井也具有良好的推广应用价值。更多还原

【Abstract】 This thesis systematically researches the cementing technique for wells of easy-channeling and with weak formations.According to the characteristics of wells of easy-channeling and with weak formations, a method of controlling annular fluids channeling is proposed combining expanding and thixotropy with lightweight cement slurry. Of the method, the annular fluids channeling is controlled by increasing the pore pressure through adding gas control additive and introducing thixotropic property into the cement slurry. The materials and additives composing the lightweight cement slurry are selected based on analysis of their characteristics. An new anti-channeling lightweight cement slurry is developed through a large number of experiments, which has the characteristic of expanding and thixotropy. The slurry system has the characteristic of low sedimentation, strong thixotropy, high compressive strength at low temperatures, anti-channeling, zero free water, low fluid loss, and adjustable thickening time. Two cement slurries are developed suitable to Lu 9 Region of Luliang Oilfield in Xinjiang. The densities of the slurries are 1.30g/cm3 and 1.50g/cm respectively. The experiments are carried out to study the influence of formation water on compressive strength of the cements.The main measures to prevent lost circulation are analyzed in wells with weak formations including the wells of easy-channeling. For the wells, a displacing method is proposed to prevent lost circulation, which changes the pump rate gradually during the displacing process. With the method., the pressure balance between formation and annular fluids can be achieved and the operation time can also be shortened. With shortened operation time, the required thickening time of the slurry can be reduced, which is beneficial to prevent annular fluids channeling and to the development of the cement’s compressive strength. The design approach of balanced-pressure cementing is given for the wells with weak formations. The balanced-pressure cementing designs are done for different kinds of casing cementing operations in Lu 9 Region.The technical measures to increase displacement efficiency are given and discussed for the wells with weak formations. Based on analysis, the following cementing fluids configuration is definitely suggested for the wells with weak formations: density of drilling fluid>densities of preflush and/or spacer< density of slurryviscosity of drilling fluid> viscosities of preflush and/or spacer<viscosity ofslurryIt is required for the preflush and/or spacer to be in turbulent flow. When using this cementing fluids configuration, the displacement of preflush and/or spacer to drilling fluid is realized by the disturbance effect of preflush’s and/or spacer’s, the displacement of slurry to preflush and/or spacer is realized by the buoyant force and the viscosity difference between the slurry and preflush and/or spacer. As a result, a high annular displacement efficiency is achieved.Through the research and field applications, an integrated technique is formed suitable to cementing the wells of easy-channeling and with weak formations. In Lu 9 Region of Luliang Oilfield in Xinjiang, field cementing tests and applications with a total operation number of 440 in 382 wells are successfully carried out. The percent of passed cementing jobs is 97.7% and the percent of excellent cementing jobs is 70.0%. The percent of excellent cementing jobs of production casings is 77.0%. By using the technique, the difficult problem is solved of cementing the wells of easy-channeling and with weak formations in Lu 9 Region. Thus, the development of Lu 9 Region of Luliang Oilfield is ensured. The cementing technique formed through this research is also suitable for other wells of easy-channeling and with weak formations like the wells in Lu 9 Region, and it has an excellent value of popularization.更多还原