水泥封固段长度对固井胶结面密封能力影响的试验研究

The Experimental Study on the Influence of the Length of Cement Sheath Isolation Section on Seal Capacity of Cementing Cementation Plane

水泥封固段长度对固井胶结面水力密封能力有不可忽视的影响,研究其影响规律有助于科学设计水泥返深,确保油气生产安全。选用南海某油田固井水泥浆体系,开展了水泥环岩石力学参数测试与水泥环胶结面CT扫描测试,基于自研的水泥环密封完整性评价装置,运用气窜法测试了高温高压养护条件下不同封固长度水泥环的水力密封能力。试验结果表明,在水泥环本体未发生破坏条件下,水泥环胶结面为气体的主要窜流通道;在同等养护及受力条件下,随着封固段长度的增加,气窜压力逐步增大。拟合了气窜压力随封固段长度的关系式,并针对封固段长度为1m条件下的模拟套管水泥环地层系统进行了模拟声幅测井,测井结果显示试验所测试的水力密封能力数据有效,进一步验证了固井胶结面为气窜的主要通道。该研究对指导高温高压井水泥返深设计具有一定的指导意义。

The length of cement sheath isolation section has significant influence on hydraulic seal capacity of cementing cementation plane.The study of its influence law is helpful for designing the top of cement depths scientifically and ensuring the safety of oil and gas production The cement slurry system of an oilfield in the south China sea was selected to carry out the test of rock mechanical parameters of cement sheath and the CT scan test of the cementation plane of cement sheath.Based on the self-developed cement sheath seal integrity evaluation device,the hydraulic seal capacity of cement sheath with different sealing lengths under high temperature and high pressure curing conditions was tested by using gas channeling method.The experimental results show that the cementation plane of the cement sheath is the main channeling path of gas under the condition that the cement sheath body is not damaged.Under the condition of equal maintenance and stress,the gas channeling pressure gradually increases with the increase of the length of the isolation section.The relation between the gas channeling pressure and the length of the isolation section was fitted,and the simulated acoustic amplitude logging was carried out for the simulated casing-cement sheath-stratigraphic system with the isolation section length of 1m.The logging results show that the hydraulic seal capacity data measured in this test are effective,which further verifies that the cementing cementation plane is the main channeling path of gas.This research has certain guiding significance to the design of the top of cement depths in high temperature and high pressure wells.