深水井精细控压下套管研究

深水窄压力窗口地层给下套管带来了巨大挑战，下套管时产生的波动压力将导致井筒压力超过压力窗口上限而出现井漏，大大增加了作业时间，采用传统方法下套管时为了防止波动压力过大而超过安全压力窗口只能降低下套管速度，这样虽然在一定程度上减小漏失风险但增大了作业成本，且这种方式不一定有效。因此，针对深水窄安全压力窗口地层下套管漏失风险问题，基于动态波动压力建立了深水窄安全压力窗口井筒压力控制模型；并在此基础上提出深水精细控压下套管方法。利用建立的模型分析井筒压力影响因素发现，井筒压力随着套管下入深度、最大下入速度、钻井液密度以及钻井液的屈服值、黏度的增大而增大。计算表明，深水精细控压下套管不但降低了漏失风险，还缩短了作业时间，降低了作业成本。

A Study of Precisely Managed Pressure During Casing Running in Deep Water Wells

Deep-water formations with a narrow pressure window pose a huge challenge to casing running. The surge-swab pressure generated during casing running will cause the wellbore pressure to exceed the upper limit of the formation pressure window and cause lost circulation. When a lost circulation occurs in offshore operation, the operating time will be greatly increased. In order to prevent excessive surge-swab pressure from exceeding the safety pressure window when using conventional methods for casing running, the casing running speed can be reduced. This reduces the leakage risk to a certain extent, it increases drilling costs, but does not apply to some wells. Therefore, for leakage risk during casing running in deep-water narrow safety pressure window formations, a deep-water narrow safety pressure window wellbore pressure control model is established on the basis of dynamic surge-swab pressure; and a deep-water precise-control managed pressure method for casing running is proposed. Using the established dynamic surge-swab pressure model to analyze the influencing factors of wellbore pressure, it is found that the surge-swab pressure of the wellbore increases with the increase of casing depth, maximum running speed, drilling fluid density, yield value and viscosity of drilling fluid. The calculation results show that shows that the precise managed pressure in deep water not only reduces the leakage risk, but also shortens the operation time and reduces the operation cost.