Coiled-tubing drilling (CTD) was a very active area of operations years ago, but it seems to have gone through a lull recently, certainly in terms of active geographic areas. However, if the papers presented at the SPE/ICoTA Coiled Tubing and Well Intervention Conference and Exhibition this March are anything to judge by, then CTD seems to be regaining some interest in the broader market.
The application of CTD in the papers featured in this issue and in the recommended additional reading highlight its use in more niche areas.
Paper SPE 189904 details the use of CTD to access marginal and bypassed reserves. Although the fields may be marginal, the effect within the US is not. As stated in the Interstate Oil and Gas Compact Commission’s 2012 report, “The hypothetical elimination of $30.8 billion in marginal oil and natural gas production in 2012 would trigger an estimated direct loss of 95,442 jobs and $4.62 billion in earnings within the oil and natural gas industry.” Accessing these potential resources spawned several projects sponsored by the US Department of Energy in the mid-1990s.
A well re-entry and sidetrack CTD operation in New Zealand is reviewed in paper SPE 189930. A niche CTD application in Australia is explored in paper SPE 189918, which revisits the placement of the coiled-tubing reel directly above the injector, with some new, unique features.
Another operational area that is enjoying a continued level of high activity is milling with coiled tubing. This is being combined increasingly with real-time downhole telemetry made available at surface. Real-time communication with coiled-tubing bottomhole assemblies has enabled engineers and operations personnel to evaluate and optimize milling through increased understanding and interpretation of data streams. Papers SPE 189910 and SPE 189942 both detail such applications, each using differing telemetry methods.
In the oil and gas industry in general, a considerable focus is being placed on well abandonment and its associated cost, especially offshore. Around the globe, well operators are developing alternatives to using traditional rigs, and, in many instances, coiled tubing is being used to perform partial or full well plugging. Alternative well-plugging materials and methods continue to be developed that could be used with coiled tubing. A 13-well, 10-month campaign of well abandonment in Norway is reviewed in paper SPE 189956.
This Month's Technical Papers
Recommended Additional Reading
SPE 189918 The Coiled-Tubing-Drilling Rig for Mineral Exploration by S. Soe, Deep Exploration Technologies Cooperative Research Centre, et al.
SPE 189930 Coiled-Tubing Drilling: Case Study, New Zealand by Soheil Kariminejad, Tag Oil, et al.
SPE 189942 First Time Coiled-Tubing Milling in 7-in.-Monobore Gas Well Using Downhole Real-Time Measurements by W.R. Tapia, Schlumberger, et al.
Alex Crabtree, SPE, Consultant
01 June 2018
Coiled-Tubing Telemetry Intervention in Shut-In Conditions
When a new horizontal well in Asia was incapable of unassisted flow, coiled tubing (CT) was selected for the perforation and stimulation intervention. Mechanical isolation was required to ensure that the stimulation fluids entered only the new zones.
Isolation Barriers With Coiled Tubing in Plug-and-Abandonment Operations
Plug-and-abandonment (P&A) operations can be expensive, leading to negative net present value. Historically, P&A operations in the North Sea—estimated to hold some 3,000 wells of declining production—were performed with either drilling or workover rigs.
Underbalanced Drilling With Coiled Tubing in Marginal Shallow Wells
The complete paper describes a recent directional coiled-tubing drilling (DCTD) job completed for an independent operator in the Appalachian Basin.
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