【摘要】 控压固井是解决复杂地层及窄安全压力窗口固井难题的有效手段之一。然而，由于水泥浆候凝期间的传压效率不明确，控压固井候凝憋压值的选取尚未考虑压力在环空传递过程中的损失，影响控压固井效果。为精确预测环空静液柱压力的下降过程，准确掌握环空浆柱传压效率的变化规律，提高控压固井候凝期间的防窜效果，基于候凝期间的压力传递实验，结合胶凝悬挂理论和弹性应变能理论，引入水泥水化动力学理论，建立了固井候凝阶段传压效率预测模型，并进行了实例应用。研究结果表明：(1)水泥浆的传压效率在候凝期间逐渐降低，其下降趋势与失重趋势相同，与静胶凝强度发展趋势相反；(2)随着温度升高，水泥浆失重速率和静胶凝强度发展速度加快，40～80℃条件下，水泥浆静胶凝强度达到240 Pa时的传压效率为45%～48%；(3)建立的固井候凝阶段水泥浆的传压效率预测模型平均误差小于7%，与实验数据吻合较好，基于该模型计算得到传压效率影响因素敏感性排序为温度>浆柱长度>环空间隙>候凝憋压值。结论认为，基于传压效率的控压固井可以确保在水泥浆具备防窜能力之前，封固段压力保持在安全压力窗口内并能有效压稳地层，消除固井作业的气窜风险。更多还原

【Abstract】 Managed pressure cementing is one of the effective approaches to address the cementing challenges in complex formations with narrow safety pressure windows. However, the pressure transmission efficiency of the cement slurry during the waiting-on-cement(WOC) stage is not figured out, and the pressure loss during the annulus transmission stage is not incorporated in the selection of pressure buildup value for the WOC of managed pressure cementing, which impacts the performance of managed pressure cementing. In order to precisely predict the decline process of annulus hydrostatic column pressure, accurately understand the variation pattern of pressure transmission efficiency of annulus slurry column, and improve the anti-channeling effect during the WOC stage of managed pressure cementing, this paper introduces the kinetic theory of cement hydration, based on the pressure transmission experiments of WOC process, in combination with the theories of gelling suspension and elastic strain energy. On this basis, a model for predicting the pressure transmission efficiency in the WOC stage is established and then applied practically. The following results are obtained. First, the pressure transmission efficiency of cement slurry decreases gradually in the WOC stage, and its decreasing trend is the same as the weight loss trend, but opposite to the development trend of static gel strength. Second, the weight loss rate of cement slurry and the development rate of static gel strength increase with the temperature. Under the temperature of 40 ℃–80 ℃, the pressure transmission efficiency is in the range of 45%–48% when the static gel strength of cement slurry reaches 240 Pa. Third, the average error of the proposed prediction model for pressure transmission efficiency of cement slurry during the WOC stage is less than 7%, which is in accordance with the experimental data. The sensitivity of various factors affecting pressure transmission efficiency calculated through this model is ranked as temperature > slurry column length > annulus clearance > WOC pressure buildup. In conclusion, the managed pressure cementing based on pressure transmission efficiency can maintain the pressure of cemented interval within the safety pressure window and effectively stabilize the strata to eliminate the gas channeling risks of cementing operations before cement slurry obtains anti-channeling ability.更多还原