控压钻井实时计算及控制决策方法研究

Study on Real-time Calculation and Control Decision Methods for Managed Pressure Drilling

随着石油勘探开发向边缘、深部复杂地区和非常规资源发展,窄密度窗口、高井控风险等钻井问题越来越突出。对于窄密度窗口地层,控压钻井能有效降低钻井作业难度和井控风险。但现有控压系统在无井底压力测量数据条件下的计算分析能力有限,无法实现准确指导常规控压钻井和精细控压作业实时计算分析与控制决策推荐。因此,基于现场工程录井、控压实时数据,建立了自动判断控压钻井作业工况的分支判断树,实现了11种钻井工况的实时识别。从环空液固两相流动特征着手,耦合井筒压力和地层流体侵入量,建立了控压钻井过程中的环空压力分布预测模型,实现了井口回压预控值的计算、确定和推荐。在理论研究基础上,开发了控压钻井计算分析及控制决策系统,现场测试表明:控压钻井过程中可以进行井筒压力及井口回压值模拟分析、自动识别钻井工况和井下复杂,立管压力的系统计算值与实测值之间平均误差为1.88%,基于安全作业条件的井口回压预测值与实控值符合率达到89.8%,实现了基于实时工程参数的控压钻井在线计算分析与控制决策,提高了控压钻井井口回压控制的可靠性和时效性,有效指导常规控压钻井作业,并通过流程优化提升了精细控压钻井作业能力和智能化水平。

As petroleum exploration and development expand into marginal,deep,complex areas and unconventional resources,drilling challenges such as narrow density windows and high well control risks become increasingly prominent.For formations with narrow density windows,managed pressure drilling(MPD)can effectively reduce drilling difficulty and well control risks.However,the existing MPD systems have limited computational analysis capabilities without downhole pressure measurement data,making it impossible to accurately guide real-time calculation,analysis,and control decision-making for conventional and fine-tuned MPD operations.Therefore,based on field engineering logging and real-time MPD data,an automatic judgment branch decision tree for MPD operations was established,enabling real-time identification of 11 drilling conditions.Starting from the characteristics of annular liquid-solid two-phase flow,coupling wellbore pressure and formation fluid invasion volume,an annular pressure distribution prediction model during the MPD process was established,achieving the calculation,determination,and recommendation of wellhead backpressure pre-control values.On the basis of theoretical research,an MPD calculation analysis and control decision system was developed.Field tests show that during MPD operations,the system can simulate and analyze wellbore pressure and wellhead backpressure values,automatically identify drilling conditions and downhole complexities.The average error between the system′s calculated values and the measured standpipe pressure values is 1.88%,and the conformity rate between the predicted and actual wellhead backpressure values under safe operating conditions is 89.8%.This realizes real-time MPD online calculation,analysis,and control decision-making based on engineering parameters,improving the reliability and timeliness of wellhead backpressure control in MPD operations,effectively guiding conventional MPD operations,and enhancing the capability and intelligence level of MPD operations through process optimization.