High Performance Wellbore Departure and Drilling System for Accessing New Target

Dewey, Charles; Swadi, Shantanu; Alsup, Shelton; Desai, Praful C.

doi:10.2118/138001-ms

All Days 2011

DOI: 10.2118/138001-ms

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High Performance Wellbore Departure and Drilling System for Accessing New Target

Charles Dewey

Shantanu Swadi

Shelton Alsup

et al.

Abstract: Conventional wellbore departure and drilling systems generally require the operator to make multiple downhole trips to achieve a specific objective. For example, a window milling bottom hole assembly (BHA) is run in hole to create an exit path in the existing casing and drill sufficient rathole for the next drilling assembly. In the subsequent trip, a directional drilling BHA is run to extend the rathole and drill laterally to the target. The industry requires an economical solution to accomplis… Show more

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Cited by 3 publications

References 9 publications

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Innovative Whipstock Technology / Procedures Successfully Complete Challenging Low-Side, Uncemented Casing Exits: UK North Sea

Finlay

Bain²,

Fairweather³

et al. 2012

All Days

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Maximizing profitability in mature fields is dependent on reducing drilling and operational expenses to maintain optimized hydrocarbon production. As Forties field UK North Sea matures, drilling challenges are becoming increasingly more difficult and complex. Wellbore instability caused by the loss of reservoir pressure and anisotropic properties of overburden shale is a major issue as targets are pushed further away from the platform. To continue successful development of Forties field, the operator is required to drill high-inclination deviated wellbores sidetracked from existing boreholes. The unstable shale outside of the sidetrack window requires a low-side casing exit. To optimize operations the sidetrack must be completed on the first attempt. When a first sidetrack fails, a second is often initiated approximately 10m (or interval thereof) further up in the wellbore with a higher mud weight. Unable to get more than a few feet away from the original wellbore within such a short distance, the new sidetrack can frequently re-enter the zone already damaged by the previous attempt and again runs into trouble. This broken formation becomes even more destabilized with increased mud weight. To solve the operational / economic challenges, a unique wellbore departure system was developed to deliver fast, high-quality windows and sidetracks tailored specifically to meet operator’s low-side application objectives without compromising performance. The low-side exit requires a unique set of pre-job equipment modifications which is performed in the service provider’s workshop prior to shipping equipment to the well-site. The modification allows an upward force to be exerted at the tip of the whip face on setting the permanent packer / anchor thereby overcoming the natural gravitational forces. This upward force does not come into effect until the packer is energized, thus ensuring the whipstock assembly remains flexible enough to mitigate wellbore tortuosity encountered whilst running in the hole. The system was successfully applied initially on three challenging uncemented whipstock sidetracks with single-trip window success (up to 77° inclination / 180° orientation). On all three jobs the anchoring and milling technology worked flawlessly with no issues when subsequently tripping directional BHA or liners through the window. Application engineers performed pre / post-job briefings with service provider’s rig site / offshore supervisors to ensure specific low-side exit guidelines were followed and that lessons learned or suggestions for improvement were captured and documented for prosperity. The authors will present Forties field case studies that document procedural repeatability and how the tools and techniques could be used for any challenging low-side uncemented casing exits.

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Innovative Whipstock Technology / Procedures Successfully Complete Challenging Low-Side, Uncemented Casing Exits: UK North Sea

Finlay

Bain²,

Fairweather³

et al. 2012

All Days

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Managing Drilling Risks Associated with Wellbore Departure: Modeling Increases System Reliability while Reducing Operational Costs

Zhang

Chen

Geng

et al. 2014

Day 1 Mon, November 10, 2014

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A typical method to sidetrack from a cased well is to use a milling assembly to traverse an anchored whipstock to create a window, and then continue to drill a rathole deviating from the original well. A sidetrack can also be conducted in an open, uncased wellbore. The operation usually utilizes a directional BHA to traverse anchored or cemented whipstock and drill ahead while steering away from the original wellbore. To achieve a successful wellbore departure, it is critical to minimize shock/vibration to avoid failure of the milling assembly and drillstring components. The milled window should allow sufficient clearance for the subsequent BHA to pass through without issues. The rathole also needs to deviate away to avoid collision into the original wellbore. Modeling with the capability to evaluate wellbore departure is valuable to plan the operation and avoid unexpected malfunctioning. The authors describe how a time-based modeling system was used to simulate drillstring dynamics and the cutting action of casing mills. Extensive laboratory tests were done to capture the interaction between the cutting elements/casing, whipstock, cement and formation. The data and the parameters from the specific application were then fed into the model for simulation. The results include milled window profile, rathole wellpath, BHA shock/vibration, and drillstring bending moment/stresses. By studying different scenarios, the milling assembly, BHA and drilling parameters were optimized to reduce the potential for vibration and chance of breakage, and to ensure appropriate window size and rathole length. Gantry milling tests were conducted in the laboratory. Milling assemblies were used to cut windows in casings cemented in steel containers. Drilling dynamics data including applied weight, RPM and flow rate were collected and analyzed. The geometry of the windows and the profiles of the whipstock were measured after the tests. This information was used to validate the model and good agreement was observed between laboratory tests and modeling results. Validation was also conducted with results from actual field milling runs/operations. The authors will present actual field examples to show the effectiveness of the model to help diagnose and prevent component failure and provide operating parameters recommendations for optimal results.

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PDC Shearing Cap Technology Protects Cutters When Drilling Out Casing Bits for Increased ROP and Bit Life in the Next Hole Section

King¹,

Leon²,

Rumbos³

et al. 2015

SPE/IADC Drilling Conference and Exhibition

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Casing drilling technology uses a specially designed casing drill bit that is attached to a traditional casing string. The technology is typically applied when hole problems such as severe formation swelling or caving cannot be controlled with drilling mud or by rig operations, making it extremely difficult to reach the planned casing setting depth. In these applications, the casing and bit are set and cemented. To drill the next section of the wellbore, the casing drill bit, as well as the float equipment, must be drilled out. In PDC bit applications this is typically done in two ways – using a roller cone bit for the drill out, followed by a new PDC bit for the next interval; or by using a single new PDC bit and BHA to drill out the cemented casing bit and continue drilling the next interval. Each method presents inherent inefficiencies in the drilling operation. With the first, additional drilling and trip time are required to run the two bits. The second method using a single new bit has the potential to damage the PDC cutters while drilling out the casing bit such that performance is limited in the next formation interval. The cutter damage is heightened when using a bent motor assembly. This degraded cutter condition negatively affects bit durability and performance, resulting in slower rates of penetration, shorter runs, and pulling the bit before completing the intended interval. Milling cap technology has been developed for the single-bit method that provides a shearing action during the casing bit drill out process while protecting the primary PDC face cutters. It preserves the cutters in virtually pristine condition so that performance is optimized when drilling the formation. The shearing cap technology allows flexibility in selecting the best performing bit for the interval below the casing, and it increases the opportunity to use a bent motor assembly when drill string rotation is required during the drill out. This paper discusses the development of the shearing cap technology and examines the two initial field tests in South America and West Africa. In the first use of the technology, drilling on a well in Colombia, an 8 ¾-in. PDC drill-out bit with shearing caps completed the drill out portion of the run in less than 15 minutes. The bit then drilled the next 4,900 foot formation interval to the next casing point with an ROP 5% higher than the field average. The bit showed no signs of reduced ROP after the drill out and came out of the hole in good condition with a dull grade of 1-2-CT-G-X-I-BT-BHA. In West Africa, a 12 ¼-in. PDC bit with shearing caps produced the best performance in the field, reducing casing bit drill out time by 44% and improving ROP in the formation by 50% compared to offsets.

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High Performance Wellbore Departure and Drilling System for Accessing New Target

Cited by 3 publications

References 9 publications

Innovative Whipstock Technology / Procedures Successfully Complete Challenging Low-Side, Uncemented Casing Exits: UK North Sea

Innovative Whipstock Technology / Procedures Successfully Complete Challenging Low-Side, Uncemented Casing Exits: UK North Sea

Managing Drilling Risks Associated with Wellbore Departure: Modeling Increases System Reliability while Reducing Operational Costs

PDC Shearing Cap Technology Protects Cutters When Drilling Out Casing Bits for Increased ROP and Bit Life in the Next Hole Section

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