Rehm / Haghshenas / Paknejad Underbalanced Drilling: Limits and Extremes

1. Auflage 2013
ISBN: 978-0-12-799980-7
Verlag: Elsevier Science & Techn.
Format: EPUB
Kopierschutz: Adobe DRM (»Systemvoraussetzungen)

E-Book, Englisch, 629 Seiten

Reihe: Gulf Drilling Guides

The present crude oil and natural gas reservoirs around the world have depleted conventional production levels. To continue enhancing productivity for the remaining mature reservoirs, drilling decision-makers could no longer rely on traditional balanced or overbalanced methods of drilling. Derived from conventional air drilling, underbalanced drilling is increasingly necessary to meet today's energy and drilling needs. While more costly and extreme, underbalanced drilling can minimize pressure within the formation, increase drilling rate of penetration, reduce formation damage and lost circulation, making mature reservoirs once again viable and more productive. To further explain this essential drilling procedure, Bill Rehm, an experienced legend in drilling along with his co-editors, has compiled a handbook perfect for the drilling supervisor. Underbalanced Drilling: Limits and Extremes, written under the auspices of the IADC Technical Publications Committee, contain many great features and contributions including: - Real case studies shared by major service companies to give the reader guidelines on what might happen in actual operations - Questions and answers at the end of the chapters for upcoming engineers to test their knowledge - Common procedures, typical and special equipment involved, and most importantly, the limits and challenges that still surround this technology

Autoren/Hrsg.

Rehm, Bill

Haghshenas, Arash

Paknejad, Amir Saman

Al-Yami, Abdullah

Hughes, Jim

Leseproben

Preface
P.E. Don Hannegan,     Weatherford International Ltd. Jim Hughes,     SunStone Technologies LLC Where Have We Been and Where are We Going?
The purpose of this book is to discuss the limits and extremes of underbalanced drilling (UBD) technology and its enabling tools, a formidable task by any measure. The world’s first commercially successful hydrocarbons well was drilled underbalanced, with what today would be considered akin to a cable tool rig. It is likely that the world’s last well will be drilled underbalanced due to the grossly depleted nature of future reservoirs. In fact, the world’s last hydrocarbons well will likely not be for conventional oil or gas because those reserves will have been exhausted. It will likely be drilling for commercial quantities of the world’s last abundant resource of hydrocarbons energy, methane hydrates. Given that methane hydrates disassociate in accordance with Boyles Law, it is reasonable to suspect that those drilling programs will dictate the use of UBD concepts and key enabling equipment. This defines the limits of UBD application, and warrants no additional discussion. The extremes of UBD, on the other hand, causes one to reflect upon the extremities of the technology which have positively impacted the upstream industry and the greater promise it holds for the future. UBD’s trademark benefits, which range from drilling into grossly depleted formations without damaging the prospects productivity to increasing recoverable reserves by enabling the drilling of otherwise un-drillable prospects, remain core values of the technology. However, its extremities are also reflected in the manner in which the technology has facilitated and/or complimented the development of other drilling methods needed to expand exploration and production. UBD has also fostered the development of a suite of technologies that have proven to be invaluable in the development of new tools, and has contributed immensely towards safer drilling practices to the benefit of the upstream industry as a whole. UBD has been a technology incubator of benefit to the industry as a whole. Drilling methods that do not invite the well to flow in the process of being drilled have benefited from lessons learned from UBD’s safe and effective practices. First and foremost, UBD challenged conventional wisdom by encouraging drilling decision-makers to rethink the way they view the hydraulics of drilling. In the process they have become more receptive to alternatives to the conventional wisdom that has been primarily used since the industry learned to drill with weighted mud systems over a century ago. Therefore, this preface will focus upon the extremes or extensions of UBD’s root concepts and the enabling equipment that have had a significantly positive impact on the broader cross-section of the upstream industry, particularly as it relates to drilling complex wells, both onshore and offshore, safely and effectively. 1.1 UBD’s Contribution to Hydraulic Flow Modeling
The practice of UBD often involves drilling with two-phase fluids and drilling where surface equipment requirements must handle multiphase annulus returns. Compressible fluids within the drillstring and annulus necessitate a profound development in hydraulic flow modeling technology; to design the UBD fluid, estimate optimum circulating rates, establish surface equipment specifications for pressure containment capability and flow rates, and serve as an invaluable data resource for pre-drill planning, HazId/HazOp processes, etc. Hydraulic flow modeling capabilities initiated by UBD requirements have now been extended to be beneficial to any drilling operation where there may be compressible fluids in the wellbore. For example, early kick detection is enabled by software with UBD roots. Sophisticated “candidate selection” methods of determining whether Air/Mist/Foam drilling, UBD, or managed pressure drilling (MPD) is the best drilling method for a prospect or a zone have been enabled by the teachings of UBD hydraulic flow modeling. 1.2 UBD’s Contribution to the Development of Rotating Control Devices
Air/Mist/Foam Drilling, Underbalanced Drilling, and Managed Pressure Drilling require drilling with a closed-loop fluids system. A key enabler is a rotating control device (RCD) of required pressure containment capability and preferably of a design requiring minimum modifications to the existing rigs mud returns system. Although low-pressure capable RCD’s (500 psi, or less) were available to the drilling industry decades earlier, it was not until 1989 that demand for higher pressure capable designs began to surface. Attempting to drill horizontally with conventional methods into the inclined fractures of abnormally pressured Texas Austin Chalk presented a well control concern. Loss circulation occurred, followed almost immediately by a severe influx of reservoir fluids into the wellbore, a “hard kick”. The development of the world’s first 1,000 psi capable RCD enabled the well to flow safely while drilling proceeded. The practice of underbalanced drilling played a key role in fostering widespread usage of the RCD’s on conventional mud drilling programs. Most importantly, UBD requirements of the tool precipitated the development of high-pressure designs with redundant annular sealing elements. A widely perceived value of drilling with a RCD on conventional drilling programs was proven to be a statistically valid premise in a study entitled “Recent Trends in RCD Usage and the Incidence of Blowouts” conducted by the University of Texas. The study tested for a statistical relationship between blowouts and Rotating Control Device (RCD) usage on conventional mud drilling programs. It concluded “We find consistent statistical evidence, across a variety of regression models; the use of RCD’s decreases the incidence of blowouts.” Today, RCD designs are readily available that are suitable for the practice of all drilling methods that benefit from closed and pressurizable circulating fluids systems, whether the drilling program is on land, shallow water, deep water, or ultra-deep water. 1.3 From Underbalanced Drilling to Pressurized Mud Cap Drilling
Pressurized mud cap drilling (PMCD) is a crossover between underbalanced drilling and managed pressure drilling. The bottom of the hole up to the lost zone is very much an underbalanced operation, and from the lost zone to the top of the hole it is a managed pressure operation. The pressure is managed at the surface but is underbalanced at the bottom of the hole. Much of the Pressurized Mud Cap Drilling activity in the Asia Pacific region falls into the contingency category. On average, operators incur severe or total loss scenarios on only one out of five wells. Operators are increasingly implementing contingency plans as they balance out the cost of stand-by rates on the equipment against a potential loss of the well. At least one major operator has established an internal practice that suggests if a drilling program manager does not prepare to practice PMCD in a region known to have severe loss-circulation issues, then a formal HazId/HazOp process should be conducted to prove it is better not to invest in a PMCD contingency. 1.4 UBD’s Contribution to MPD
UBD root concepts and enabling equipment have played a key role in prompting the development of another drilling method—one that many in the upstream industry today believe will be applied on 40% of all offshore drilling programs within the next 5 years—managed pressure drilling (MPD). MPD is a technology transference from UBD and would not have achieved the broad industry acceptance it has demonstrated without being strongly rooted in the basic concepts of UBD. Although MPD does not invite the well to flow in the process of being drilled, the method requires some of the same equipment: drill-string non-return valves, fit-for–purpose RCD, and a dedicated choke manifold. MPD also requires the same degree of pre-planning, hydraulic flow modeling, HazId/HazOp processes, crew training, and inter-active drilling program implementation that are characteristic of safe and effective UBD. 1.5 Combinations of Drilling Methods: Conventional Mud Drilling, MPD, UBD
As drilling expenditure uncertainties and low energy prices drive operators toward stronger contingency plans that assure a successful drilling program, MPD has gained favor on conventional-wisdom fluids and well construction programs, onshore and offshore. Such a MPD “Contingency Plan” allows operators to react more efficiently and safely when dealing with unexpected downhole pressure environments. MPD as a contingency to conventional drilling programs sets the tone for an UBD contingency when practicing MPD. MPD does not invite the well to flow, so what would happen if there is a 20% chance if encountering a zone that, for index reasons alone, begs to be allowed to flow while it is being drilled? All of the required surface equipment is in place, with the exception of a means of dealing with the produced hydrocarbons. A 20% chance...