Enhanced Real-Time Wellbore Stability Monitoring Using High-Definition Imaging With Wired-Pipe Telemetry

Abstract

Many fields currently being drilled by the petroleum industry require the use of high angle, extended reach wells to access remote hydrocarbon deposits. Although pre-drill geomechanical modeling efforts are often carried out to define the mud weight window, many wells still experience significantly elevated drilling costs due to non-productive time (NPT) associated with wellbore instability. This can be attributed to many factors but is predominantly due to the lack of appropriate data while drilling. Since rock properties, stresses and pore pressure often vary from the pre-drill model predictions, critical wells frequently require real-time updating of the geomechanical models using relevant logging while drilling (LWD) data to facilitate accurate, real-time decision-making. In this paper, a case history is presented where memory-quality; high-definition LWD image logs were obtained via high-speed telemetry systems and used to assess wellbore conditions in real time. The high-resolution LWD images were used to detect faults/fractures, breakout and general hole enlargements. Relog images over known unstable sections were also obtained to ascertain the extent of time-dependent wellbore failure. These logs were successfully used to delineate the failure zones and apply the appropriate mitigating actions in real time. Introduction In today's petroleum industry, pre-drill geomechanical modeling efforts are routinely undertaken in fields where significant wellbore instabilities are known to exist. In many cases, comprehensive and robust pre-drill models can be developed that provide great value in that they can be used to design a well and drilling fluid program to mitigate wellbore instability (Evans etal. 2003). However, it is not always possible to construct a robust pre-drill model due to a variety of reasons (e.g., insufficient useful data). This combined with the fact that significant geological uncertainties may still exist, may limit the effectiveness of pre-drill geomechanical models when applied to a current drilling campaign. This fact is borne out by a Gulf of Mexico study (Dodson et al. 2004) suggesting that wellbore integrity-related incidents (hole collapse, kicks and lost circulation) represent a major source of non-productive rig time (despite the development of sophisticated geomechanical modeling capabilities). The study indicated that 37% of the total drilling NPT stems from geomechanical and pressure-related downtime, which consume 24 to 27% of the total drilling costs. Standifird & Keaney (2004) suggested that as much as 40–50% of all NPT is attributable to pore pressure, fracturing and hole instability. This costs the industry an estimated US$26 billion annually (Sweatman 2006). It is our contention that to effectively reduce or even eliminate this NPT, diagnosing wellbore failure in real time (and applying the appropriate mitigating action while drilling) is the key. This is most easily accomplished using high definition LWD image logs. Discussion of Image Logs LWD borehole images provide critically useful information in terms of borehole quality and position within the reservoir (Janwadkar et al. 2007; Lindsay et al. 2006; Lofts et al. 2005; Morris et al. 2006a, 2006b; Onu et al. 2008; Ritter et al. 2004; Stamm et al. 2007). When used in real time, these images can help with making decisions on drilling hazard mitigation and well placement during drilling (Lindsay et al. 2007; Morris et al. 2008). Recent advances in telemetry rates (Hernandez et al. 2008) show that higher resolution image quality, approaching or equaling that of memory data, is now available in real time. This technology has enabled the visualization of geomechanical features at sufficient resolution to be useful for real-time decision-making applications.

A study of a technological development process: Human factors—the forgotten factors?

“…During the last decades, the number and complexity of large and complex technical installations, such as those for petroleum, aviation, and nuclear 6 industries, have increased (e.g. Stamnes, Zhou, Kaasa, & Aamo, 2008;Strøm, 2008;Wilpert, 2005;Wolfe, Morris, & Baule, 2009). With the growth of complex installations, the possibility of dangerous consequences for humans and the environment also are increasing.…”

A Summary Of Wired Drill Pipe Field Trials And Deployments In Bp

“…During the course of drilling these wells many wired pipe enabled applications and benefits were experienced. Some of these have been the subject of previous papers both from BP and other operators (Wolter et al, 2007;Olberg et al 2008, Ali et al, 2008Wolfe et al, 2009;Allen et al, 2009;Hatch et al, 2011;. Some of these benefits are quite obvious and were anticipated.…”

Wellbore Construction Improved by Real-Time Borehole Images

“…Furthermore, maximum and minimum stress directions are inferred from the orientation and shape of drillinginduced tensile fractures and /or the width and azimuth of breakouts. Real-time image data aids in updating geomechanical models and monitoring wellbore integrity, which was previously demonstrated for example by [16,17,19]. The geomechanical model calibration workflow is fed by automatically determined breakout orientations and widths ( Figure 5).…”