Computing Collapse Pressure for Coiled Tubing

Avakov, Vladimir; Fowler, Hampton

doi:10.2118/36340-ms

Cited by 6 publications

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Design and Qualification of an Ultra-High Pressure Perforating System

et al. 2012

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With the steadily increasing demand for oil and gas, operators have been forced to explore deeper and hotter areas to find the most prolific reservoirs. This paper hightlights the design and qualification steps performed during development of a 7.0-in. O.D. 16 shots per foot (SPF) 30,000 psi perforating gun system. Finite-element modeling was used to optimize the gun design for 30,000 psi external pressure, and 400° F. As part of the qualification requirements, ballistic survival testing was conducted using low-debris gravel pack shaped charges.Comprehensive knowledge of the post-perforated condition of the gun body is required, as its failure may lead to an expensive fishing operation and possible damage of the oil well casing. Survival testing was conducted under two different conditions, no load on the gun body and the second contion with a tensile load equivalent to the weight of 1,500 ft of perforating guns.The methodology of finite-element modeling is discussed along with experimental data obtained by collapse testing of perforating hollow carriers (HC) of different diameters and shot densities. Data from computer simulations and physical testing in the lab are presented to provide better insight into the behavior of perforating guns under external pressure. The data from the survival tests showed virtually no change in the swell of the HC when subjected to a high tensile load as compared to the no-load condtion. This testing method provides insight into the behavior of perforating systems under different loading parameters.The results described in this paper highlight the need to apply rigorous methods for design and qualification of ultra-high pressure gun systems when exploring new oilfield frontiers characterized by extremely harsh environmental conditions.

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Design and Qualification of an Ultra-High Pressure Perforating System

et al. 2012

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30 Years of Continuous Coiled Tubing Modeling Software Development and Field Applications Creating New Capabilities

Aitken

Livescu

Craig

2018

SPE/ICoTA Coiled Tubing and Well Intervention Conference and Exhibition

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During the last three decades a coiled tubing (CT) modeling software package has been continuously developed to assist in the planning and executing of global CT operations. The first models were steady-state. In the past decade these models have been extended to consider transient effects of operations as they are executed. These models will also be used in the not-so-distant future to automate CT operations. In this paper, a review of all these models is presented for the first time. The development of a computer program was initiated in the early 1980s to help understand the downhole flow and pressure conditions during CT operations. Utilizing multi-phase rheological and frictional correlations obtained from laboratory flow loop testing, the CT flow model was extensively validated against global field data. Later, CT force and stress analysis models, considering such effects as the specific well geometry, mechanical friction, CT size, shape and material strength, were developed to predict lateral reach and assist in preventing downhole CT failures. While the most common and simplest approach within the industry is still to use steady-state models, in practice, the downhole conditions during CT operations, such as well cleaning, well unloading, well control, stimulation, cementing, underbalanced drilling with nitrified fluid, etc., are transient. Consequently, the steady-state models have been extended to account for downhole transient effects at the pre-planning and execution stages of CT operations. In addition, with the advent of the state-of-the-art CT telemetry systems, it is possible to acquire the downhole data in real time and use the transient CT software model to automate and optimize CT operations, increasing their safety and efficiency. A review is presented for the first time about the steady-state and transient models included in the CT software model, with details about each model and how they performed during 30 years of operations. Results and discussions regarding the extensive validation of the software against laboratory and field data are also presented. Several field cases from around the world help illustrate the transient nature of CT operations and the benefits of using the transient simulation in the pre-planning and execution stages of these operations. The paper presents the results from 30 years of global experience with the CT modeling software program. The mathematical models, validation against laboratory and field data, verification against other models available in literature, and case histories are described. The current trends within the industry are leading to a shortage of experienced CT field engineers, so the use of CT software models to increase the efficiency, compliance and safety of CT operations has never been as important as now.

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