September 1998 Vol. 219 No. 9  Drilling

J. John Grow,  Engineering Editor

Oilfield requirements: brains, brawn and an adventurous spirit

Since its inception, the oilfield has required brains, brawn and an exceptional need for adventurous spirit, especially during these tough times of low oil prices and mega-mergers. With technological advancements, our skills are challenged constantly, brawn is called upon to endure excessive travel, and harsh environmental surroundings. An adventurous spirit is mandatory for oilfield survival. An ability to adapt to an ever-changing "standard" and increasing one's knowledge bank is an asset we all can use.

With all the joint ventures, takeovers and joining of forces taking place in this new round of oilfield mergers, it is interesting to note how the major players manipulate their expertise and capital during our most recent oil price declines. What are some of the projects we are to embrace and their potential outcome? For one, a recent joint venture to develop and commercialize expandable casing has gained notoriety; that concept is presented below.

Expandable casing JV. Shell and Halliburton are going to develop and commercialize expandable casing technology, originally developed by Shell; and it promises to significantly reduce drilling costs, especially in deepwater regions like the Gulf of Mexico. Shell Technology Ventures, Inc. (Shell) and Halliburton Energy Services (HES) limited liability, a 50/50 company, is to be launched by fourth quarter, 1998.

Expandable casing is slotted or solid, high-strength, ductile steel pipe. Slotted casing has a series of staggered, overlapping axial slots cut into it. The slot pattern allows for up to 300% radial expansion. Typical expansion is 50% with less than 1% overall contraction. Solid-casing radial expansion is from 20% to 25% of its original diameter. The expansion process strain-hardens the metal keeping its burst/collapse properties essentially constant.

Briefly explained, after a well section is drilled, expandable casing (either slotted or not) is run, in the usual manner. Once in place, a mandrel (pig) is run to expand the casing, Fig. 1. The mandrel can be pushed, pulled or pumped through the casing, depending on application. For example during drilling, expansion could be from top down, say for an intermediate string controlling an unconsolidated or depleted zone. For well completions, expansion could be from downhole upward, e.g., across perforations for sand control without gravel packing. Initial testing demonstrated that the casing can be expanded at a rate of 100 ft/min and expands from 20% to over 50% of it's original size.

Successful development of expandable casing technology will help O&G operators access reservoirs not easily reached with current methods. By expanding casing in situ, hole size is maintained and targets can be reached with minimal well tapering. The results are obtained through improved reservoir economics by reducing well capital expenditures and improving success rates in reaching sub-salt targets. In addition to rig-time savings and lower well costs, expandable casing technology will result in overall smaller-hole size from spud to TD, Fig. 2. Expandable pipe also has applications in patching and cladding existing casing.

Thanks go out to Shell's Bruce Stewart, principal research engineer, tubular expansion systems and co-author of SPE paper 36828, An expandable slotted tubing, fibre-cement wellbore lining system, 1996, Tim Frank, venture development manager and Richie Pickens, VP marketing for giving their time and participation in helping to develop a better understanding of what is involved in this new technology. Also, thanks to Rich Hansen, public affairs manager who was instrumental in setting up our teleconference.

New logging record in Gulf of Mexico. Schlumberger has successfully completed the deepest logging job ever performed in the GOM. An EEX Corp. well was logged with new-generation tools deployed on drill pipe. Formation data was acquired to 25,772-ft TVD, max. well deviation of 28° and hydrostatic pressure to 19,968 psi.

Copyright © 1999 World Oil
Copyright © 1999 Gulf Publishing Company