摘要
Abstract
To address the challenge of accurately determining shut-in drill pipe pressure(SIDPP)under complex well conditions such as a layer with simultaneous overflow and lost circulation,a research method integrating theory with practice was adopted.By analyzing key factors affecting SIDPP determination and overflow treatment cases from Wells MX145,ST1,and HS101 in the Sichuan Basin,this study discussed the methods and experiences for determining SIDPP under complex well conditions.The following research results are obtained.(i)For wells that are shut due to overflow in the formation with narrow drilling fluid density window,the post-shut-in pressure buildup in wellbore easily leads to lost circulation,making the conventional pressure buildup method fail in determining the SIDPP.In this case,the circulation method is recommended;or,the possible range of formation pressure for the overflow well is estimated by analyzing the drill pipe/casing pressure curves,combined with the data from offset wells.(ii)When the pressure buildup method is used to obtain SIDPP,the time to read the pressure is a key consideration,that is,the drill pipe/casing pressures at the time of pump shut-down,rather than the value before pump shut-down,should be recorded.(iii)For long open-hole sections with multiple formation pressure coefficients,the SIDPP may not truly reflect the current formation pressure,and the complex well conditions such as lost circulation-to-overflow transition can be mitigated or prevented through pressure-bearing capacity test,preemptive formation energy release,and managed pressure drilling techniques.The study concludes that SIDPP determination is somewhat challenging under complex well conditions,but accurate calculation of the static liquid level height within the wellbore and proper interpretation of wellhead pressure variation enable the derivation of relatively accurate SIDPP value,providing a reliable basis for well control and kill operations.关键词
关井立管压力/钻井液窄密度窗口/溢漏同层/精细控压钻井/漏转溢/井控/溢流/憋压法Key words
Shut-in drill pipe pressure/Narrow drilling fluid density window/Layer with simultaneous overflow and lost circulation/Managed pressure drilling/Lost circulation-to-overflow transition/Well control/overflow/Pressure buildup method
