Enhancing Well Safety and Economics
| Autor: | Deepak Manilal Gala, Bill Menard, Steve William Nas, Mike Offner |
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| Rok vydání: | 2010 |
| Předmět: | |
| Zdroj: | Journal of Petroleum Technology. 62:24-27 |
| ISSN: | 1944-978X 0149-2136 |
| DOI: | 10.2118/0610-0024-jpt |
| Popis: | Technology Update As the “low-hanging fruit” of the world’s oil and gas accumulations are more fully harvested, so the industry has been forced into tackling more complex and challenging projects such as ultradeep prospects, deepwater applications, and high-pressure/high-temperature (HPHT) wells to continue fulfilling the world’s appetite for fossil energy. This has led to more widespread use of nonconventional techniques such as drilling with casing, coiled-tubing drilling, underbalanced drilling (UBD), and managed-pressure drilling (MPD), including pressurized-mud-cap drilling (PMCD), with their attendant well-control and safety challenges. Among these challenges are Moderate to severe lost circulation Formation damage as a result of having to kill the well before tripping pipe Pore-pressure and fracture-gradient similarity, leading to kick/loss cycles and well-control problems Use of snubbing techniques to trip the pipe in and out of the hole above the “pipe-light” depth, with the associated added cost and risk. Overall operational safety Operational economics As a result, mitigating drilling hazards and reducing operational non-productive time (NPT) has become an extremely important facet of well operations. Downhole-Isolation-Valve System The need to address these challenges led to development of the Downhole Deployment Valve in the year 2000. This is an isolation-valve system consisting of a deep-set flapper valve that is run as an integral part of the intermediate casing string and set at a predetermined depth below the pipe-light depth, or deeper as operational requirements dictate, with a full-opening inside diameter equivalent to that of the casing. It is not a safety valve in the accepted sense of the word, in that it is not a fail-safe device, but rather is powered open and closed by the application of hydraulic pressure at the surface to one of two encapsulated control lines attached to the casing outside diameter (OD). The downhole isolation valve (DIV) can be run in two separate configurations, depending on operational requirements (Fig. 1). |
| Databáze: | OpenAIRE |
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