Floatation of 10¾-in. Liner—A Method Used to Reach Beyond 10 km

Eck-Olsen, Johan; Sletten, Haakon; Løklingholm, G.

doi:10.2118/105839-ms

Cited by 10 publications

(2 citation statements)

References 8 publications

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“…liner was run in hole with an 8 1 =4-in. reamer shoe to enable the liner to be worked down with rotation (Eck-Olsen et al 1994, 2007Alfsen et al 1995;Hjelle et al 2006). The actual torque values in the open hole showed that rotating the liner was impossible.…”

Section: Well Designmentioning

confidence: 99%

North Sea World Record Installation–Deepest Sealed Multilateral System

Eck-Olsen

Solheim

Falnes

2012

SPE Drilling &Amp; Completion

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In October 2010, the deepest-set sealed multilateral (ML) junction in the industry was installed at 6900-m measured depth (MD) in Oseberg South Well 30/9-F-9 AY1/Y2. The differential pressure across the junction in the well was expected to be in the range of 250 bar. To meet this pressure requirement, a junction system rated to 370 bar was identified. The high-pressure junction components and entire multilateral system have undergone an extensive testing and qualification program, including several component tests and a full-scale system interface and integration test.A 10 3 =4-in. precut window was installed as an integral part of the 10 3 =4-in. liner. The plan was to perform the milling operation through this window. A stuck-string incident during the 10 3 =4-in. liner installation accidentally caused the liner to drop in the hole. The liner ended up at the wrong orientation, and the window could consequently not be used.The main bore was drilled to total depth (TD) at 8583-m MD, and the 7-in. liner was run and cemented. After the liner perforation, the BL operations started with the installation of an anchor packer and a latch interface assembly (LIA). The milling operation was performed in a two-step operation with milling of a first-pass window by use of a downhole milling machine before installing a whipstock and performing the second-pass milling operation.The lateral branch was drilled to TD at 8258-m MD, and a 5 1 =2in. screen completion was run and dropped off into the 8 1 =2-in. open hole. The junction was finally stung into a completion deflector, simultaneously with an openhole seal stinger entering the top of the screen liner in the open hole, tying the branches together. A 6900-m upper completion string with inflow control valves was finally installed to allow for surface control of the two branches.Despite severe drilling problems in the transport sections of the well, the ML operations were deemed successful. Major risk and challenges with this well design involved orientation of the 10 3 =4-in. liner (to position the premilled window) at this depth, debris management after milling operations, and general depth control during junction construction. Debris management in particular became essential as the backup ML solution meant milling steel rather than aluminum.Although the two different reservoirs could be drained by two conventional extended-reach-drilling (ERD) wells, this would be a less cost-efficient solution. Furthermore, the construction of an ML well means that the aforementioned challenges drilling the transport sections had to be handled only once. The successful installation at this depth has proved that ML technology is feasible for use in ERD wells, either to improve the total reservoir exposure or to reach multiple targets from one well.

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Section: Well Designmentioning

confidence: 99%

North Sea World Record Installation–Deepest Sealed Multilateral System

Eck-Olsen

Solheim

Falnes

2012

SPE Drilling &Amp; Completion

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“…Mitchell (2002a, b) developed two new buckling solutions for horizontal wells by use of Jacobian elliptic functions. Recently, Gao and Miska (2008) studied the effects of end conditions and friction on static buckling in horizontal wells. They showed that if the dimensionless length of pipe is greater than 5p, the effects of boundary conditions can be ignored.…”

Section: Introductionmentioning

confidence: 99%

Buckling of Buoyancy-Assisted Tubulars

Arslan¹,

Ozbayoglu

Miska

et al. 2014

SPE Drilling &Amp; Completion

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Use of buoyancy provides multiple solutions to overcome the drag problem for wells with shallow and high step-out profiles. Although both full-and partial-flotation methodologies have been used successfully to extend the reach in many field cases, the influence of buoyancy on tubular instability has not been investigated yet. This paper presents an extensive experimental and analytical study, focusing on static tubular instability inside horizontal wellbores with emphasis on buoyancy. In terms of the experimental research, running tubulars into horizontal wellbores was simulated with four different pipes, varying buoyancy, and varying loading speed. Throughout the tests, axial loads both applied to the pipe and transmitted through the pipe were recorded simultaneously, with respect to pipe displacement. Experiments reveal that currently existing models give reasonable approximations as long as buoyancy is not included in the tests. The major interpretation from the experiments is contrary to what currently existing expressions imply (i.e., tubular buckles immediately as effective weight approaches zero; even for naturally buoyant conditions, considerable amount of axial load is still required for both buckling initiation and helix formation). As buoyancy increases further, results and predictions diverge from each other considerably. To eliminate the discrepancies between results and predictions, theoretical study was conducted. Empirical correlations that also consider the influence of buoyancy on critical buckling loads are presented. Finally, another pipe was also tested within different buoyancy conditions to validate the equations developed. Experimental results of this pipe closely match the new analytical findings. This experimental and analytical study provides useful results for future applications with buoyancy-assisted tubulars, in terms of practical engineering and design calculations.

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Backing Off a Free Drillstring: Planning and Execution on a World-Class ERD Well

Eck-Olsen

Foster

2007

All Days

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Since the inception of horizontal and Extended Reach wells, operators have faced the deviation-related complications that arise when dealing with stuck pipe and pipe recovery operations. Drillstring washouts in particular create a problematic situation in an ER drilling operation, as it necessary to spend extensive time circulating and rotating at high rates to sufficiently clean a high angle wellbore to a level that allows a safe and trouble free trip1,2,3. When a washout occurs prior to the completion of the cleanup process (which they almost always do), the operator is faced with a difficult choice:continue to circulate until the hole is clean, running the risk of enlarging the washout and potentially creating a twist-off, orattempt to pull out of a dirty hole, which may (and often does) result in tight hole and/or stuck pipe. A case history is presented where a drillstring washout occurred on a long extended reach well prior to the completion of the cleanup process. Attempts to trip the string proved futile, and it became apparent that the string would probably become stuck during further attempts to pull out of the hole. A modified version of the traditional backoff technique was safely used to separate the pipe below the washout without the drillstring actually being stuck. The entire string was subsequently recovered, saving >13MM NOK (2MM USD) in lost time and equipment. This is believed to be the first ever successful backoff of a free drillstring. Introduction High angle and extended reach wells present many technical challenges, most of which require "unconventional" solutions as compared to vertical or low-angle wells6. Fishing operations are no exception. Often, the most favorable option for dealing with stuck pipe in vertical wells is to perform a backoff of the drillstring. The primary advantage of this time-proven technique is that it allows the drillstring to be separated from the stuck section and reconnected with full mechanical integrity. However, in order for a backoff to be a viable option in a vertical well, the drillstring must be rotationally stuck at some point in the well. In unique circumstances, it is desirable to disconnect from the drillstring with the intention of reconnecting at a later time. The most common instance in high angle wells is an untimely drillstring washout prior to cleanup of a "dirty" hole. Unlike vertical wells, the drillstring does not necessarily need to be stuck in a highly deviated well for the backoff technique to be feasible. By applying detailed torque and drag analysis and "energy isolation" measures, fit-for-purpose procedures can be developed to safely backoff a drillstring that is not stuck. High Angle Fishing Challenges To understand the logic behind why a backoff is more favorable than "conventional" disconnection methods, one must first explore the difficulties that arise in high angle fishing operations. These difficulties can be separated into two categories: Separation The first step in separating stuck pipe is to identify where the pipe is stuck. In situations where circulation is possible, pumping down diagnostic and severing charges is a common solution. In the unfortunate circumstance that circulation cannot be established, wireline tractor technology is required for conveyance4 in wells above ±70° inclination. For higher tangent angles (75°-80°), coil tubing intervention also requires tractor technology due to helical buckling. Once the stuck point is determined, the same sophisticated conveyance methods required for detection are also necessary for severing. In these environments, the only separation technique that does not require intervention is the "blind backoff"5. Unfortunately, the blind backoff technique is quite imprecise (accidental backoff of a connection above the intended location), and requires that the pipe be stuck (in vertical and high angle wells).

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Floatation of 10¾-in. Liner—A Method Used to Reach Beyond 10 km

Cited by 10 publications

References 8 publications

North Sea World Record Installation–Deepest Sealed Multilateral System

North Sea World Record Installation–Deepest Sealed Multilateral System

Buckling of Buoyancy-Assisted Tubulars

Backing Off a Free Drillstring: Planning and Execution on a World-Class ERD Well

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