The greatest risk to operational safety during the drilling and completion of a well is a kick. A gas influx, with its potential for escalation into well control event, places the crew, the environment and the rig in imminent danger.The second greatest risk is misdiagnosis of an event and the failure to quickly and correctly take action.For kicks and other pressure related events, the question is often fundamental-"are we experiencing losses or is the well ballooning during a connection"? The answer can be critical. An incorrect decision based on a misdiagnosed situation can result in millions of dollars in non-productive time (NPT). In the extreme, incorrect diagnosis can lead to death and injury, environmental damage and the loss of the rig.These risks to well control and drilling efficiency are being mitigated using a handful of common oilfield technologies that are the key elements of closed-loop circulating system-rotating control devices (RCDs), flow-metering technologies, automated drilling choke systems and downhole isolation valves. This is truly an instance of the whole being greater than the sum of the parts. That value is being further enhanced through the integration of innovative analysis and management software. These closed loop systems have proven very successful in mitigating risk and improving economics across a wide range of land and marine drilling applications and are allowing the industry to safely tackle it's most risk-laden and costly wells.The elements are field proven-some with more than a 40-year history-readily available from numerous vendors and are relatively economical. Individually they add incremental safety and efficiency benefits. However, when these elements are paired or used in combination with each other to create a closed and pressurizable mud-returns system, the benefits escalate at an exponential rate. This paper examines the basics elements of a closed-loop circulating system and how this technology is enhancing the safety and efficiency of drilling and completion operations without sacrificing other operational elements. A Costly ProblemWellbore instability and the resulting drilling hazards are a major source of risk to the safety, operations and economics when drilling and completing wells. York et al analyzed non-productive time (NPT) in Gulf of Mexico deepwater operations resulting from stuck pipe, well control and fluid loss. (York et. al, 2009) In non-subsalt wells the report found these hazards accounted for 5.6% of total well time and 31% of total NPT. In subsalt wells the metric doubled to 12.6% of total well time and 41% of NPT. (Figure 1) In a well of 20,000 ft MD, extrapolated losses in 2009 were equated to $2,500,000 and $7,660,000 respectively. These metrics do not include the total well failures resulting from drilling hazards. A more recent study shows that in the GOM, pressure related events such as kicks, lost circulation and stuck pipe make up 48% of incidents when drilling conventionally. (Figure 2)
fax 01-972-952-9435. AbstractFluid invasion of a reservoir during conventional overbalanced drilling operations can cause considerable formation damage. Increased awareness of the degree of damage possible has raised interest in the benefits that underbalanced drilling (UBD) offers. UBD techniques are not necessarily suitable for all reservoirs but can provide significant benefits in certain instances.During UBD operations, the formation is allowed to flow; so a surface pressure is ever present in the annulus. A rotating control head is used to control the pressure. As tripping begins and the pipe is stripped through the wellhead, the pressure must be managed to prevent a pipe-light situation.Killing the well to control it and allow for conventional tripping of drillstring is not always a viable solution; and, until recently, the only accepted method for tripping drillstring in a constant underbalanced state has been snubbing, which can have operational and economic drawbacks in some situations. This paper describes how implementation of the downhole deployment valve (DDV) in a Southern North Sea drilling program reduced overall program costs, set multiple records, and demonstrated successful integration of a new technology into one of the most critical underbalanced operations in the world.
fax 01-972-952-9435. AbstractFluid invasion of a reservoir during conventional overbalanced drilling operations can cause considerable formation damage. Increased awareness of the degree of damage possible has raised interest in the benefits that underbalanced drilling (UBD) offers. UBD techniques are not necessarily suitable for all reservoirs but can provide significant benefits in certain instances.During UBD operations, the formation is allowed to flow; so a surface pressure is ever present in the annulus. A rotating control head is used to control the pressure. As tripping begins and the pipe is stripped through the wellhead, the pressure must be managed to prevent a pipe-light situation.Killing the well to control it and allow for conventional tripping of drillstring is not always a viable solution; and, until recently, the only accepted method for tripping drillstring in a constant underbalanced state has been snubbing, which can have operational and economic drawbacks in some situations. This paper describes how implementation of the downhole deployment valve (DDV) in a Southern North Sea drilling program reduced overall program costs, set multiple records, and demonstrated successful integration of a new technology into one of the most critical underbalanced operations in the world.
The rapid development of unconventional energy plays such as shale oil & gas necessitates "assembly line" approach to well construction and completion technologies. Due to very high number of wells being drilled to explore such promising resources, novel approach to optimize well construction process is necessary. This requires an industrial engineering approach to not only remove non-productive time out of the assembly process, but also drive out the invisible flat time and unrealized inefficiencies of the manufacturing process. This paper will discuss the application MPD to maximize drilling efficiency by optimizing drilling parameters to minimize Mean Specific Energy (MSE) for drilling.Managed Pressure Drilling (MPD) techniques have gained industry wide acceptance for drilling technically challenging prospects and also helping to minimize risks associated with well control and lost circulation hazards. The well construction process in shale plays might be perceived as more benign than some of the challenging environments such as deep-water. However application of MPD to maximize drilling efficiency in shale plays can minimize cost by reducing the field development time.MPD has been shown to reduce the drilling time by almost 50% through the elimination of known and unknown drilling inefficiencies. Overall drilling performance is impacted through the inherent ability of MPD to quickly identify and control any pressure events and continue drilling versus spending costly time fighting down hole problems. MPD also significantly impacts performance through the optimization of parameters such as mud weight and Equivalent Circulating Density (ECD).MSE has been a great tool to quantify drilling efficiency. Effect of different drilling parameters such as mud weight, weight on bit and torque on MSE will be discussed. Application of MPD has significant impact on MSE during drilling. This paper will describe how the use of MPD on shale developments, along with other unconventional developments improves the overall drilling efficiency hence allowing for quicker & safer well construction and field development. It will also investigate the added benefit of MPD improving field production through better understanding of productive zones and fracture identification.
Deep water projects are presently complex, where more drilling challenges can be encountered and higher uncertainty increases the risk of problems during the well construction phase, especially due to the narrow pressure window environments. Managed Pressure Drilling (MPD) is one of the technologies that is currently gaining acceptance since demonstrating that it helps control these problems, minimizes the risks, and optimizes the overall well construction process in deep water applications. MPD is being used not only during the drilling phase, including techniques such as Constant Bottom Hole Pressure (CBHP) and Pressurized Mud Cap Drilling (PMCD), but also is being implemented because of the benefits of identifying and controlling formation influxes while drilling and/or during connections, controlling wellbore pressures during connections, and while tripping in and out of the hole. Continuous circulation systems (CCS) are also widely used in exploratory wells to enhance control of the wellbore pressure during connections and are being used either in conjunction or without MPD. Once the well has been drilled and the completion has been run in hole, the next step is cementing the casing or liner in place. Managed Pressure Cementing (MPC) can also be implemented and brings additional benefits during this phase such as more precise control of the pressures, allowing the use of lighter fluids, and better monitoring of the overall process. Different case histories from several areas will be described in this paper to illustrate the drivers, implementation, and results of the various MPD techniques that can be used during the well construction phase including CBHP, PMCD, CCS, and MPC. The paper will also highlight the synergies among these different technologies and how they would further benefit deep water operations.
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