Microhole technology involves adapting conventional coiled tubing to ultrasmall-diameter boreholes, in the range of 3-4-in. diameter and smaller than a commercially defined “slimhole.”
Los Alamos National Laboratory (LANL) conducted a feasibility study that examined the possibilities of microhole development in terms of existing and needed technologies.
Microhole I
NETL’s Strategic Center for Natural Gas and Oil has awarded development funding for systems to operate in 31⁄2-in. boreholes to 5,000 ft in two rounds. Six companies received $3.74 million in funding in the first solicitation round, announced in 2004 (www.pttc.org/alerts/NETL04.pdf):
- Baker Hughes Oilfield Operations Inc. (for 23⁄8-in. geosteering and LWD system).
- Bandera Petroleum Exploration LLC (for a zero-discharge mud system for microhole coiled-tubing drilling).
- Gas Production Specialties (for a through-tubing electrical submersible micropump).
- Schlumberger IPC (for a built-for-purpose microhole coiled-tubing rig).
- Stolar Research Corp. (for a radar navigation and radio data transmission for microhole coiled-tubing bottomhole assemblies).
- Western Well Tool Inc. (for a microhole horizontal-drilling tractor).
Microhole II
In January 2005, NETL awarded $7.7 million in research funding to another 10 companies in the second solicitation (OGJ, Feb. 21, 2005, p. 49):
- Geoprober Drilling Inc. (for drilling three wells with a composite coiled-tubing drilling system).
- Gas Technology Institute (for field testing the MOXIE microhole coiled-tubing rig, developed by Dallas-based Coiled Tubing Solutions).
- Confluent Filtration Systems LLC (to develop a self-expanding tubular technology-CFEX).
- Tempress Technologies (to develop a high-pressure waterjet drilling tool).
- CTES LP (to improve performance and reliability of microhole bottomhole assemblies by introducing vibration).
- Technology International Inc. (to develop and test a downhole drive and coiled-tubing drillbit for 31⁄2-in. holes-Turbodrill).
- Ultima Labs Inc. (to combine existing MWD and LWD systems into an inexpensive microhole system and deliver two prototypes).
- Baker Hughes (to develop a wireless steerable drilling system for coiled-tubing).
- Gas Technology Institute (to develop a counter-rotating motor drilling system for coiled tubing).
- Confluent Filtration Systems (to develop and deploy self-expanding, high-flow downhole sand screens).
