Particle Size Distribution Improves Casing-While-Drilling Wellbore- Strengthening Results

Watts, Rick; Greener, Micheal Rodney; McKeever, Stephen O.; Scott, Paul D.; Beardmore, David Hale

doi:10.2118/128913-ms

Cited by 24 publications

(11 citation statements)

References 6 publications

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“…Such characteristics could be associated with the uncertain concept of smear effect, but that analysis is excluded from this document. Nevertheless, the ratio of casing OD to borehole inner diameter was higher than 0.8 and, as suggested by some authors, could be linked to wellbore strengthening (Watts et al 2010).…”

Section: Cementing Drill-in Stringmentioning

confidence: 72%

Casing While Drilling (CwD): A New Approach To Drilling Fiqa Formation in the Sultanate of Oman—A Success Story

Sánchez¹,

Houqani²,

Turki

et al. 2012

SPE Drilling &Amp; Completion

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Highly reactive Fiqa shale used to compel well engineers in the Sultanate of Oman to plan drilling phase of surface and intermediate sections primarily based on time exposure to aqueous drilling fluid water-based mud (WBM). The new approach of drilling the time-dependent Fiqa formation using casing-while-drilling (CwD) allows well engineers to plan prospective top/intermediate wellbore sections differently by enhancing the overall drilling performance. This reduces the risk of setting casing strings at unplanned depths, getting pipe stuck, or reaming continuously when drilling with conventional drillstring. The technical feasibility study, risk assessment, planning, execution, and the lessons learned during the process of drilling two top-section pilot projects are described in this document. The CwD team compares the drilling performance of several offset wells and suggests actions to improve the CwD technology in Oman.Two 17 1 =2and 22-in. surface sections were drilled successfully with large-diameter casing strings and reached 754-and 894-m measured depths, respectively. The implementation of the CwD concept reduced the overall drill/case phase time up to 40%, in comparison with the average using conventional drilling in those fields. Exposure time of Fiqa to aqueous environment was reduced by eliminating conditioning trips and nonproductive-time (NPT) associated with wellbore instability. Drilling both sections with non-retrievable 17 1 = 2 Â13 3 = 8 -in. and 22Â18 5 = 8 -in. CwD systems did not require modification of well design or rig. The optimization of this technology will support its implementation as the conventional drilling approach in some fields in Oman.

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Section: Cementing Drill-in Stringmentioning

confidence: 72%

Casing While Drilling (CwD): A New Approach To Drilling Fiqa Formation in the Sultanate of Oman—A Success Story

Sánchez¹,

Houqani²,

Turki

et al. 2012

SPE Drilling &Amp; Completion

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“…This process increases the fracture gradient of the formation in near wellbore area, which results in a wider operational mud weight window. In one Casing Drilling case study, the open hole leak-off resistance was improved by 4.6 ppg (Watts et al 2010). This effect has been observed in permeable and impermeable formations.…”

Section: Superior Hydraulicsmentioning

confidence: 85%

“…Nunzi et al (2010) reached the same conclusion and believe that adopting the Casing Drilling/Liner Drilling technology has the potential of eliminating contingency strings in deepwater. Watts et al (2010) demonstrated that the Plastering Effect of Casing Drilling allows successful drilling through unstable loss zones. "If wellbore strengthening can be systematically achieved, then wells can be drilled in known loss areas without contingency strings of casing.…”

Section: Casing/liner Drilling Successful Case Studiesmentioning

confidence: 99%

“…Their study shows that a significant improvement in fracture gradient can be achieved with the right clearance between the hole and the casing and the proper sized particles added to the mud system. With confidence that strengthening can be achieved to the levels of improvement demonstrated, wells can be evaluated with significant cost savings by eliminating casing strings and preserving hole size for completions or further drilling, (Watts et al 2010). …”

Section: Casing/liner Drilling Successful Case Studiesmentioning

confidence: 99%

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A Review of Casing Drilling Advantages to Reduce Lost Circulation, Improve Wellbore Stability, Augment Wellbore Strengthening, and Mitigate Drilling-Induced Formation Damage

et al. 2011

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Casing Drilling is a process in which a well is drilled and cased simultaneously. This innovative technology has been successfully practiced for the past decade. The original purpose of developing Casing Drilling was to eliminate Non Productive Time (NPT) associated with tripping drill pipe and running casing. However, during early implementation of the technology, other benefits were observed while drilling with large diameter casing. This paper reviews four of these advantages which are lost circulation reduction, wellbore strengthening, improved wellbore stability, and drilling-induced formation damage mitigation.Casing Drilling reduces mud lost to the formation in two ways; the Plastering Effect seals off the wellbore and prevents fluid transfer between the borehole and the formation; secondly, in the worst cases where the losses can't be cured, drilling will be continued with minimized losses until the casing reaches the total depth. Reduced mud loss to the reservoir section can be directly correlated to reduced skin due to drilling induced formation damage. This leads to improved productivity of the wells drilled with casing in the reservoir section.As the Plastering creates an impermeable mud cake on the wellbore wall the pressure containment of the borehole is augmented. This process increases the fracture gradient of the formation in near wellbore area which results in a wider operational mud weight window (Wellbore Strengthening). Wells with stability problems are among the best candidates for Casing Drilling and could be drilled trouble free. The wellbore stability benefits of Casing Drilling are due to no tripping, less mud formation exposure, gauged well, superior hydraulics and borehole cleaning, etc.

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“…Undoubtedly, it represents another 'data point' for the restless analysis of the smear effect within the industry. Such analysis is excluded from this document; however, OD csg /ID hole ratio higher than 0.8 could be linked to achieved results as some authors suggest regarding strengthen the wellbore (11) .…”

Section: Cementing the 13⅜" And 18⅝" Casing Stringmentioning

confidence: 99%

Casing While Drilling (CwD); A New Approach Drilling FIQA Formation in the Sultanate of Oman. A Success Story

Sanchez¹,

Turki

Nabhani³

et al. 2010

Abu Dhabi International Petroleum Exhibition and Conference

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The highly reactive FIQA shale used to compel well engineers in The Sultanate of Oman to plan the drilling phase of surface and intermediate sections based on time exposure to aqueous drilling fluid system (WBM). The new approach of drilling the timedependent FIQA shale formation using Casing-while-Drilling (CwD) allows well engineers to plan prospect top/intermediate wellbore sections differently by enhancing the drilling performance and reducing the risk of setting casing strings shallower, external corrosion due to aquifers, and getting stuck or reaming continuosly while drilling conventionally. The technical feasibility study, planning, risk assessment, execution, as well as the lessons learned during the process of drilling top sections are described in this document. The CwD team compares the drilling performance of several offset wells and suggest actions to improve the CwD technology in Oman.Two surface sections were drilled successfully with large OD casing strings. Both surface sections 17½" and 22" reached 750m and 894m measured depth, respectively, reducing drilling phase by 40-45% in comparison with the average in the field. The exposure time of FIQA to aqueous environment was reduced considerably eliminating conditioning trips and non-productive-time (NPT) associated with wellbore instability. The volume of returns as cementing increased from 20% -with conventional drillstring -to 92-98% of pumped excess volume. CwD will allow drilling teams to slim down top holes by drilling/casing much deeper sections within less time preventing FIQA from collapsing and avoiding potential applications of Oil Based Mud (OBM). This new technology may also allow the optimization of existing rigs reducing cost and size of rig prints, as well as minimize HSE risk while handling large-OD casing and extremely heavy DC's.Simulation of the drilling phase using torque/drag and BHA-analysis software were run. The drillable PDC bit performance is compared to bit-records from offset wells recently drilled with conventional BHA's. The effect of CwD on resulting uniform cement sheath (related to the "smear effect") and the reduced size of cuttings at surface which positively aid on preventing flowline plugging as an unplanned event will be described.It is important to highlight that Nonretrievable 17½"x13⅜" and 22"x18⅝" CwD with drillable bit and the casing drive mechanism, did not require any rig modification. The optimization of the process as well as the familiarization of drilling teams with the main components of the CwD system, will lead to a long, demanding scope for its implementation in several fields in Oman.

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Particle Size Distribution Improves Casing-While-Drilling Wellbore- Strengthening Results

Cited by 24 publications

References 6 publications

Casing While Drilling (CwD): A New Approach To Drilling Fiqa Formation in the Sultanate of Oman—A Success Story

Casing While Drilling (CwD): A New Approach To Drilling Fiqa Formation in the Sultanate of Oman—A Success Story

A Review of Casing Drilling Advantages to Reduce Lost Circulation, Improve Wellbore Stability, Augment Wellbore Strengthening, and Mitigate Drilling-Induced Formation Damage

Casing While Drilling (CwD); A New Approach Drilling FIQA Formation in the Sultanate of Oman. A Success Story

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