Sidetracking technology for coiled tubing drilling

Conference · Sun Dec 31 04:00:00 EST 1995

OSTI ID:166610

Leising, L J; Hearn, D D; Rike, E A ^[1]

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1. and others

Coiled tubing (CT) drilling is a rapidly growing new technology that has been used for shallow new wells and reentry applications. A new market has evolved as being a major application for CT drilling. This market is through-tubing drilling. The lower cost of mobilization of a coiled tubing unit (CTU) to an offshore platform or Arctic wellsite vs. a rotary rig provides additional economic incentive. In addition, the ease of drilling 4-3/4-in. and smaller boreholes with CT is an advantage in a region which does not have an established practice of slimhole drilling. The remaining key enabling technology for viable through-tubing drilling is the ability to sidetrack in casing below the tubing tail. The three technologies (cement sidetracking, whipstock in cement, and through-tubing whipstock) that have been developed for sidetracking are described in this paper. A mathematical model of forces, penetration rates, and torques for window milling with the cement sidetracking technique is presented. Window milling has been a {open_quotes}seat of the pants{close_quotes} operation in the past, to the authors` knowledge, this is the first published work on the mechanics of window milling. The analysis has shed much light on the interaction between motor bending stiffness, motor bend angle, and allowable advance rates for {open_quotes}time drilling.{close_quotes} The results from several yard tests are presented, and indicate some of the problems associated with sidetracking. The photographs of the sectioned hole/window illustrate the ledges caused downhole from {open_quotes}minor{close_quotes} bottomhole assembly (BHA) changes. The cement sidetrack technique has been successfully applied many times in the field, and the results of one of these field applications is presented.

• OSTI ID: 166610
• Report Number(s): CONF-951002--
• Country of Publication: United States
• Language: English

Related Subjects

02 PETROLEUM
DRILLING EQUIPMENT
EVALUATION
OIL WELLS
REENTRY
TECHNOLOGY ASSESSMENT