降低钻井风险和增加储层钻遇率的地震导向钻井新技术

Seismic guided drilling:a technology to reduce drilling risk and increase drilling success rate

在钻井之前,需要利用地面地震资料和邻井资料进行建模、成像和物性反演,据此确定井位并进行井轨迹设计。然而,钻前一些预测结果往往与实际钻头所钻遇的地质情况相差甚远,导致钻井失利,需要改为侧钻或者直接废弃,在深海区的早期勘探或超深储藏的钻探中尤为如此。为了最大程度地降低钻井风险和缩短非生产时间,综合多学科技术,研发了地震导向钻井技术(Seismic Guided Drilling,简称SGD),包括建立地质上和地质力学上都更加合理的钻前基准地质模型(三维成像模型和岩石物理模型),提供更可靠的构造成像和层位预测结果,进一步优化布井和井轨迹设计。钻井过程中,该技术能在不影响钻井作业的情况下,将实时获得的随钻测量(MWD)和随钻测井(LWD)数据及钻井工程数据与三维地面地震数据相结合,实时更新钻前基准地质模型,使地震成像和反演精度进一步提高,并据此对钻头前方及周围的地质构造和孔隙压力预测结果进行实时更新,为实时调整钻井决策提供更加可靠的依据。

Before drilling, it is essential to use surface seismic data arid adjacent well information to create a subsurface earth model, a structural image volume, and a few estimates of the earth properties.These are used for well placement and well trajectory de sign.During actual drilling,it is often found that some of the pre-drill predictions are far from what have been encountered by the drill bit.The consequences may include drilling loss, sidetracking, or direct abandonment of the well itself. This is particularly true in early exploration of, for example, a deep water area or an ultra-deep reservoir.To minimize the drilling risks and reduce non production times, we have developed a seismic-guided drilling technology （Seismic Guided Drilling, SGD）. SGD integrates mult-disciplinary existing technical workflows to build both geologically and geomechanically more plausible pre-drill baseline earth models, including a 3D imaging modal and petrophysical properties, to create a more reasonable structure image and well prognosis, thereby helping further optimize the well placement and well trajectory.Without any impact on drilling operations, SGD utilizes existing 3D surface seismic data, MWD/LWD data, and drilling engineering data to refine the pre-drill baseline earth models in real time, further improving the accuracy of the seismic imaging and property estimation.As a result, the updated geological structure and pore pressure prediction around and ahead of the drill bit become more accurate, providing more reliable information for real-time drilling decisions.