What's happening in drilling
R&D projects lower costs, provide better risk assessmentNecessity is the mother of invention. "New" or "enhanced" technology is usually requested by a client who needs a better or more efficient method for accomplishing a task, or by field engineers who identify shortcomings of a product. A "better way" may be identified during a particular operation, and most likely R&D is requested to address the issue. Field trials are expensive and can jeopardize a well. However, with properly conducted testing and "near" field emulated conditions, failures are less likely to occur or at least not to be catastrophic. With this in mind, the following examines some recent projects currently underway. World’s first HT (up to 500°F) geothermal drilling motor. Maurer Engineering (MEI) is developing an advanced high-temperature (HT) turbodrill for drilling hard rock at high drilling rates. This turbodrill uses 50 sets of turbine blades to convert drilling mud’s hydraulic power to rotate the bit. This advanced turbodrill was developed by modifying a geothermal turbodrill used in the 1970s in LANL’s hot dry rock wells at Fenton Hill, New Mexico. A gearbox was added to reduce its speed from 1,000 to 100 rpm for use with hard rock roller bits. Improved thrust bearings are used to allow higher bit weights and increase reliability.
Phase I of the project was a major success for the geothermal drilling motor, capable of delivering high torque (4,000 to 8,000 ft-lb) to 12-1/4-in. roller bits at low speeds (80 to 120 rpm). World’s first TAML level 5 multilateral from a floating rig. Since 1996, advances in drilling and completion technologies have led to the introduction of a wide range of multilateral systems. With the large number of multilateral systems available today, it has become harder to recognize and compare functionality of one design to another. As a result, Technology Advancement of Multilaterals (TAML), a group composed primarily of North Sea operators with multilateral experience, developed a categorization system based on type and amount of support provided at the junction (junction is defined as the point at which two separate multilateral well bores merge). The current TAML categorization system consists of seven levels as described below. Level 1. Open unsupported junction Level 2. Main (mother) bore is cased and cemented, lateral is open Level 3. Main bore is cased and cemented, lateral is cased but not cemented Level 4. Both main bore and lateral bore are cased and cemented Level 5. Junction pressure integrity is achieved with completion (cement is not acceptable) Level 6. Junction pressure integrity is achieved with casing (cement is not acceptable) Level 6s. Downhole splitter with pressure integrity (large main wellbore with two smaller lateral bores). In September of this year, Baker Oil Tools completed the world’s first deepwater level 5 multilateral from a floating rig for Petrobras in Campos Basin offshore Brazil. Voador 8-VD 6HP-RJS/7HPA-RJS, drilled in 1,850 ft (565 m) of water from semisubmersible Ocean Yorktown, was drilled and completed as dual horizontal lateral injectors originating from a single wellbore in a subsea location. The well’s TVD of 9,200 ft (2,800 m) made it the deepest level 5 multilateral well ever completed. The two-wellbore junction was at 5,415 ft (1,650 m), and horizontal distance was 1,950 ft (595 m). Voador was the second level 5 multilateral injector completed using Baker’s Selective Re-entry Tool (SRT), which allows injection down a single string to be split at the junction. The company’s first level 5 multilateral to use SRT in this manner has been operating successfully on full injection in Alaska since 1997. Drilling and completion technology manager for Petrobras, Osmond Coelho, Jr., stated that the Voador project proved level 5 multilateral technology feasibility and value in deepwater operations. "Completing this well as a multilateral allowed us to reduce the number of wellheads from two to one and also saved substantial expense capitol associated with extra seabed pipeline" he said. Look for both of Petrobras’ projects, as well as a recent level 6 multilateral
completion, to be discussed in an article on multilateral completion technology in the
January 1999 issue of World Oil.
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