Casing Drilling vs. Liner Drilling: Critical Analysis of an Operation in the Gulf of Mexico

Steppe, Ray; Clark, Lester; Johns, Roger

doi:10.2118/96810-ms

Cited by 7 publications

(1 citation statement)

References 1 publication

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“…The deepwater riserless DwC operation is essentially the same as drilling with a liner 8 However, the main perceived risk is not being able to drill the casing to its required casing depth thereby leaving the LPWHH too high above the seafloor if the casing is not able to be drilled to the required depth.…”

Section: Managing the Drilling Hazards -The Risk Assessmentmentioning

confidence: 99%

Riserless Drilling With Casing: A New Paradigm for Deepwater Well Design

Kotow¹,

Pritchard²

2009

Proceedings of Offshore Technology Conference

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As the deepwater Gulf of Mexico (GOM) drilling operations move into deeper water and well depths there has been a lack of consistent and sustained drilling performance improvement. This is an evaluation of the GOM deepwater wells in an attempt to understand the reason for this poor drilling performance and propose a solution to adapt the well designs for the specific challenges of deepwater drilling. Execution of these very expensive wells, which often fail to achieve objectives, or worse are lost, requires a step change in drilling performance.The complex deepwater drilling environment has pushed the typical offshore well construction design model to its limits. Many of the well design philosophies and the well equipment itself are not well suited for the unique deepwater drilling environment. This requires step changes in well design philosophy, and the understanding and acceptance of the associated risks of implementing new practices. The acceptance of change has been a monumental driver in our industry. The goal is to ensure that exploration and development of oil and gas continues to be feasible in this industry subject to volatile commodity prices and ever increasing costs. A paradigm shift in well design philosophy that involves managing the drilling risks in the shallow hole sections, where the well costs are minimum, rather than the current practice of incurring risks after significant investment has been made, is critical to future success and economic viability of deepwater drilling. The well design model presented uses the shallow and rapid growth of the pore pressure/fracture gradient (PP/FG) environment to optimize casing seats. Drilling with Casing (DwC) is an enabling technology that can be a mitigant for managing shallow hazards. The fundamental premise is to use this technology to set the first, and possibly the second, casing strings significantly deeper than current practice.The proven ability of DwC to mitigate many similar drilling hazards as those encountered in deepwater drilling would allow the casing seats to be based upon the prevailing PP/FG environments, rather than being influenced by the shallow hazards.This could allow for the following well design improvements:• Larger annuli below salt for improved drilling margin management.• Less total casing strings in the well.• More use of conventional casing strings sizes for drilling and geological contingencies.• Enhanced planning and use of solid expandable systems.• Decreasing the risk of not obtaining at least an 8-½ in. ID completion, essential for economic success in deepwater environments. • Batch drilling into salt, which optimizes horsepower as well as cost, utilizing smaller capacity rigs for the lighter hook load casing lifts.

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Section: Managing the Drilling Hazards -The Risk Assessmentmentioning

confidence: 99%

Riserless Drilling With Casing: A New Paradigm for Deepwater Well Design

Kotow¹,

Pritchard²

2009

Proceedings of Offshore Technology Conference

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Underbalanced Liner Drilling

Sanford¹

2012

Underbalanced Drilling: Limits and Extremes

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Successful Application of Casing-While-Drilling Technology in a Canadian Arctic Permafrost Application

Vrielink¹,

Bradford

Basarab

et al. 2008

IADC/SPE Drilling Conference

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The JV operator was looking for a combination of technologies to optimize drilling in Canada's Mackenzie Delta region. The area is characterized by a permafrost section up to 2,000 ft (609 m) thick. This shallow permafrost section is dominated by unconsolidated silt with freshwater ice ranging from 60% volume to pure ice layers. Historically, mechanical heat input has melted the frozen layer, resulting in increased hydrates/shallow gas risks, extreme hole enlargement/cleaning problems, rig support issues, wellbore instability, stuck pipe, hydraulic isolation, and environmental impact issues. Optimizing drilling operations through the shallow section is critical to maximize the number of wells that can be drilled with the available rigs in this limited-access area. To move the rig requires approximately 3 ft (1 m) of ice cover, which significantly limits the operating season, increasing the need for rig efficiency and reduction of non-productive time (NPT). The industry has endorsed the importance of mud cooling through the shallow permafrost and the underlying hydrate-bearing formations to avoid borehole instability and to control hydrate dissolution. However, the industry has struggled to maintain sufficiently cold mud at the high pump/power rates required to effectively drill/clean the larger surface holes. To solve the challenges, the operator utilized a casing-while-drilling (CwD) and casing bit system with a unique-to-the-industry mud-chilling technology and a variety of controlled drilling parameters. The CwD and casing bit system allowed the operator to drill and set casing through the problematic zones in one operation with relatively low flow rates to avoid hole enlargement. The lower flow rates also enabled the use of smaller, lighter rig equipment that reduced the required ice thickness to move the rig and therefore increase the winter season operating period. Following the successful implementation of the CwD and casing bit system on the first well of a winter program, the second well was drilled safer with the elimination of a casing string, which further reduced drilling time and cost. Introduction Oil and gas operators have explored in the Arctic regions of northern Canada, Alaska, and Russia for more than 40 years. Early drilling campaigns encountered significant problems drilling through the shallow permafrost sections due to degradation of drilling conditions as a result of permafrost thaw. Experience from these earlier operations and experiments conducted by Kutasov et al (1988) has highlighted the need to maintain chilled drilling mud to minimize permafrost thaw during the well construction process. Production operations in the Canadian Arctic have not yet reached development stage. Industry experience in other Arctic regions, including Alaska—as well as Canadian National Energy Board (NEB) regulations—dictate a need to protect permafrost substrata through the entire life cycle of the well.

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Casing Drilling vs. Liner Drilling: Critical Analysis of an Operation in the Gulf of Mexico

Cited by 7 publications

References 1 publication

Riserless Drilling With Casing: A New Paradigm for Deepwater Well Design

Riserless Drilling With Casing: A New Paradigm for Deepwater Well Design

Underbalanced Liner Drilling

Successful Application of Casing-While-Drilling Technology in a Canadian Arctic Permafrost Application

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