Cementing-related problems frequently occur in gas wells with small annular space and under other unique well conditions,which will frustrate the operators in the implementation of technical measures in further well development.In recent years,based upon the previous studies on how to improve the cementing quality of gas wells,the latest research also focuses on a special cementing unit of enhancing both the slurry performance and the displacement efficiency of annular drilling fluid.Thus,a drillable downhole hydraulic pulsing generation unit with high capacity displacement and low-frequency & self-excited vibration is developed according to the fluid's self-excited vibration theories,simulation results,and the optimized design.This unit's external diameter is 177.8 mm,its working pressure is at 0.5-1.5 MPa,its working displacement is of 25-30 L/s,and its pressure pulse output frequency is of about 10 Hz;this unit uses round thread casing coupling for connection,and is quite easily drilled through by roller bits or PDC bits.The unit was successfully used for the cementing with φ177.8 mm liner in the Anyue Block of the Sichuan Basin,which proves that the unit is reliable and the cementing quality is highly improved.This technology is initially used in the cementing of intermediate casing of the borehole to be further deepened,which helps expand the scope of application of vibration cementing technology in the cementing quality improvement of oil and gas wells.

常用套管扶正器不能改变钻井液流动方向,而一些带滚子的螺旋式扶正器或螺旋式旋流扶正器又增加了制造难度.为此,研制了YX型刚性套管扶正器.通过流场模拟分析了扶正器高度及扶正棱高度对流体衰减的影响,以及扶正棱截面对过流特性的影响,并最终确定了相关几何参数.YX型剐性套管扶正器在保证套管居中的基础上,能在一定程度上改变传统的一维轴向流顶替方式,有效替净环空被顶替液,从而有利于将环空窄边滞留钻井液和井壁附着滤饼驱替干净,进一步提高固井质量.

针对现有井下振动装置在应用上存在局限性的问题,结合现场工程实际,在系统调研的基础上,提出了新型强制复位井下低频水力振动装置的设计方案.装置工作时,在液压力作用下柱塞压缩弹簧下行,卸压孔、泄油孔依次打开,环空压力升高;泄流后弹簧推动柱塞上行复位,依次关闭泄流孔、卸压孔,环空压力降低;柱塞往复运动产生环空流体压力波动.新型振动装置具有良好的固井工况适应性,适应于常规固井工艺和特殊井况;可针对施工水泥浆密度、排量进行输出参数调控.PL003-03井的应用表明,全井段固井质量优良率达到84%.

How to control water and gas channeling and to improve the displacement efficiency of cement slurry is always big concern especially for the smaller annular space because this is very important for further stimulation and production in the later period. Based on the mechanism study, many tests were carried out on how the cement pulsation treatment acts on the performance of cement slurry, with focus on the determination of the operating parameters and the optimization of this slurry system, and a new type of low frequency downhole hydraulic cement pulsation device was studied and worked out. Field tests and application practices showed that cement pulsation accelerates the hydration process of cement slurry, shortens the interval time between initial and final cement gelling, and then abates gelling weight loss effect, and this newly-developed device is feasible and practical to be widely used in the cementing operation.