A field-trialed ball-activated Outflow Control Device (OCD) is presented that eliminates coiled tubing intervention in SAGD injection wells when converting from steam circulation to SAGD. This paper builds on a previously presented paper by the same authors where the design and tool qualification of the ball-activated OCD was presented (
The field trial of the ball-activated OCD is compared to coiled tubing shiftable OCDs on three main criteria: job efficiency, confirmation of shift, and environmental, health, and safety (EHS) considerations. Acoustic-based monitoring equipment and pressure signatures were used to confirm successful ball-activation of the ball-activated OCD. A tension response from the coiled tubing was used to confirm shifting of the coiled tubing shiftable OCDs. Steam modelling and observed tubing pressure drop data is also shared for all trials as another indication of successful shift.
In five of six ball-activated OCD shifts, the tools functioned as intended with clear pressure and acoustic signatures confirming a successful shift of the sliding sleeve. One of six was intentionally left closed. In addition, the jobs were completed more efficiently and with less EHS risk than the coiled tubing shiftable OCDs. The coiled tubing shifting tension data indicated that two out of six coiled tubing shiftable OCDs were successfully shifted, with inconclusive shifts occurring on three OCDs, and one left intentionally closed. The observed pressure drop data presented, indicates that shifting was successful in all ball-activated trial wells, and two of three coiled tubing shiftable trial wells.
The ball-activated OCD is a novel tool for use in SAGD injector wells to improve efficiency by reducing operational time and personnel required in shifting OCDs. In addition, the shift confirmation pressure signature and optional acoustic monitoring provides greater confidence of sleeve shift.
Acid-tunneling is an acid jetting method for stimulating carbonate reservoirs. Several case histories from around the world were presented in the past showing optimistic post-stimulation production increases in open-hole wells, comparing to conventional coiled tubing (CT) acid jetting, matrix acidizing, and acid fracturing. However, many questions about the actual tunnel creation and tunneling efficiency are still not answered. In this paper, the results of an innovative full-scale research program involving water and acid jetting are reported for the first time.
The tunnels are constructed through chemical reaction and mechanical erosion by pumping hydrochloric (HCl) acid through conventional CT and a bottom-hole assembly (BHA) with jetting nozzles and two pressure-activated bending joints that control the tunnel initiation directions. If the jetting speed is too high and the acid is not consumed in front of the BHA during the main tunneling process, then unspent acid flows toward the back of the BHA and creates main wellbore and tunnel enlargement with potential wormholes as fluid leaks off, lowering the tunneling length efficiency.
Full-scale water and acid jetting tests were performed on Indiana limestone cores with 2-4 mD permeability and 12-14% porosity. Many field-realistic combinations of nozzle sizes, jetting speeds, and back pressures were included in the testing program. The cores were 3.75-in. in diameter by 6-in. in length for the water tests, and 12-in. in diameter by 18-in. in length for the tests with 15-wt% HCl acid. The jetting BHA was moved as the tunnels were constructed, at constant force on the nozzle mole, to minimize the nozzle stand-off distance. Six acid tests were performed at the ambient temperature of 46F and two at 97F. The results from the acid tests show that the acid tunneling efficiency can be optimized by reducing the nozzle size and pump rate. The results from the water and acid tests with exactly the same parameters to match the actual CT operations in the field show that the tunnels are constructed mostly by chemical reaction and not by mechanical erosion. The acid tunneling efficiencies obtained from the full-scale acid tests are superior to the average tunneling efficiency of more than 500 actual tunnels constructed during more than 100 acid tunneling operations performed to date worldwide.
The paper describes the full-scale water and acid jetting tests on Indiana limestone cores. The major novelty of this test program consists of performing all measurements with back pressure, unlike all previous water and acid jetting studies reported in literature, to more accurately mimic the downhole well conditions. The novel understanding of the combined effect of the nozzle size, pump rate, and back pressure significantly improves the actual acid-tunneling efficiency.
A study by a real-time monitoring company showed that many coiled-tubing strings are retired with a lot of life left in them. It suggested companies could lower costs by using pipe for a longer time and could benefit from multicompany studies showing how their decisions compare to the competition. A coiled-tubing selective perforating and activation system that transmits critical downhole data and measurements in real time is enabling well interventions that previously could not have been executed. This year’s papers provide examples of efficiencies that have been brought about in coiled-tubing operations. The papers demonstrate how problem-solving techniques have been applied to improve such aspects as on-site processes, fit-for-purpose equipment, and more-effective treatment placement.
A study by a real-time monitoring company showed that many coiled-tubing strings are retired with a lot of life left in them. It suggested companies could lower costs by using pipe for a longer time and could benefit from multicompany studies showing how their decisions compare to the competition. This paper describes a methodology for classification of artificial-lift-system (ALS) failures and addition of a commonly used root-cause failure classification. The great majority of wells do not pollute.
A study by a real-time monitoring company showed that many coiled-tubing strings are retired with a lot of life left in them. It suggested companies could lower costs by using pipe for a longer time and could benefit from multicompany studies showing how their decisions compare to the competition. This paper describes the integrated approach taken by Petronas to reinforce effective management of fatigue. The installation of flowlines in ever-deeper and -more-remote areas requires specific technologies for precommissioning. Coiled tubing can be a solution, but long durations may affect tubing stress and fatigue.
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. Larger-diameter coiled tubing recently has been used to perform millouts because of its improved set-down force and increased annular velocities for cleanout purposes. Service companies and operators have reduced the number of wiper trips when using larger-diameter CT, to save time and money.
A study by a real-time monitoring company showed that many coiled-tubing strings are retired with a lot of life left in them. It suggested companies could lower costs by using pipe for a longer time and could benefit from multicompany studies showing how their decisions compare to the competition. This paper presents a factory-model approach to improving CT drillout performance that has been used successfully for more than 3 years and has become standard practice. The coiled-tubing (CT) industry, like other well-intervention segments, has applied lean philosophies to some aspects of its management, operations, processes, and equipment. When it comes to CT application to specific in-well operations, no two wells are the same.
Across the Middle East and North African region, wells are being drilled at ever increasing depths and lengths. Wells that several years ago would have been unthinkable to reach with traditional intervention techniques are now becoming the norm, and novel techniques, equipment, tools, and products are being developed and implemented to reach even further. Stimulation and chemical placement continue to drive production recovery in some areas, while the application of digital tool technologies and extended reach interventions allows unlocking some well potential. The coiled tubing utilisation is also becoming evident for supporting frac-ing activity both conventional and unconventional reservoirs. This two-day workshop will provide an open space for coiled tubing equipment manufacturers, service providers, operators, and downhole tool providers to share their latest advancements and case studies that enlightens the conception of coiled tubing as a workover intervention technique.
Coiled tubing supports fracturing operations in a variety of situations, including preparation of the wellbore, manipulation of downhole equipment and millout of plugs. Since early 2011 coiled tubing has gained momentum for annular treatments and fracturing through coiled tubing. The advent of coiled tubing actuated sleeves helped operators complete wells with minimum post stimulation intervention. Coiled tubing can also be used in combination with downhole assemblies such as straddle packers for re-fracs, which have helped operators optimise existing completions. In recent occasions, the use of “intelligent” coiled tubing systems enabled comprehensive diagnostics pre/post stimulation. The challenges of deviated wells further emphasise the need for a solution that can be deployed rapidly and cost-effectively with broad operational boundaries to support the development of unconventional resources. This session will discuss the latest developments and field applications of coiled tubing as intervention method for fracturing operations.