Cui Zhihua, Ai Chi, Lv Lei, Yin Fangxian
School of Petroleum and Environmental Engineering, Yan'an University, Yan'an, Shaanxi Province, China.
Key Laboratory of Education Ministry for Enhanced Oil Recovery, Northeast Petroleum University, Daqing, Heilongjiang Province, China.
PLoS One. 2017 Nov 16;12(11):e0187279. doi: 10.1371/journal.pone.0187279. eCollection 2017.
The shear swirling flow vibration cementing (SSFVC) technique rotates the downhole eccentric cascade by circulating cementing fluid. It makes the casing eccentrically revolve at high speed around the borehole axis. It produces strong agitation action to the annulus fluid, makes it in the state of shear turbulent flow, and results in the formation of pulse pressure which affects the surrounding rock stress. This study was focused on 1) the calculation of the pulse pressure in an annular turbulent flow field based on the finite volume method, and 2) the analysis of the effect of pulse pressure on borehole stability. On the upside, the pulse pressure is conducive to enhancing the liquidity of the annulus fluid, reducing the fluid gel strength, and preventing the formation of fluid from channeling. But greater pulse pressure may cause lost circulation and even formation fracturing. Therefore, in order to ensure smooth cementing during SSFVC, the effect of pulse pressure should be considered when cementing design.
剪切旋流振动固井（SSFVC）技术通过循环固井液使井下偏心叶栅旋转。它使套管围绕井眼轴线高速偏心旋转。它对环空流体产生强烈的搅拌作用，使其处于剪切紊流状态，并导致形成影响围岩应力的脉冲压力。本研究聚焦于：1）基于有限体积法计算环形紊流场中的脉冲压力；2）分析脉冲压力对井眼稳定性的影响。从积极方面看，脉冲压力有利于提高环空流体的流动性，降低流体凝胶强度，并防止流体形成窜流。但较大的脉冲压力可能导致漏失甚至地层压裂。因此，为确保SSFVC固井过程顺利，固井设计时应考虑脉冲压力的影响。
