Method and system for accessing subterranean deposits from the surface

Abstract

Improved method and system for accessing subterranean deposits from the surface that substantially eliminates or reduces the disadvantages and problems associated with previous systems and methods. In particular, the present invention provides an articulated well with a drainage pattern that intersects a horizontal cavity well. The drainage patterns provide access to a large subterranean area from the surface while the vertical cavity well allows entrained water, hydrocarbons, and other deposits to be efficiently removed and / or produced.

Description

RELATED APPLICATIONS [0001] This application is a continuation of U.S. application Ser. No. 10 / 256,412, filed Sep. 26, 2002 by Joseph A. Zupanick and entitled “Method and System for Accessing Subterranean Deposits From the Surface”, which is a continuation of U.S. application Ser. No. 09 / 885,219, filed Jun. 20, 2001 by Joseph A. Zupanick and entitled “Method and System for Accessing Subterranean Deposits from the Surface”, now U.S. Pat. No. 6,561,288, which is a continuation of U.S. application Ser. No. 09 / 444,029 filed Nov. 19, 1999 by Joseph A. Zupanick and entitled “Drainage Pattern with Intersecting Wells Drilled from Surface”, now U.S. Pat. No. 6,357,523, which is a continuation-in-part of U.S. application Ser. No. 09 / 197,687 filed Nov. 20, 1998 by Joseph A. Zupanick and entitled “Method for Production of Gas From a Coal Seam”, now U.S. Pat. No. 6,280,000.TECHNICAL FIELD OF THE INVENTION [0002] The present invention relates generally to the recovery of subterranean deposits, an...

AI Technical Summary

Benefits of technology

"The present invention provides an improved method and system for accessing subterranean deposits from the surface. It involves drilling a substantially vertical well bore from the surface to the subterranean zone. An articulated well bore is drilled from the surface to the subterranean zone, which intersects the vertical well bore at a junction proximate to the subterranean zone. A substantially horizontal drainage pattern is drilled from the junction to the subterranean zone, which allows for efficient removal of water, hydrocarbons, and other fluids from the subterranean zone. The invention also provides an improved method and system for preparing a subterranean zone for mining, as well as producing methane gas from a mined coal seam. Additionally, the invention provides an improved positioning device for automatically positioning down-hole pumps and other equipment in a cavity."

Problems solved by technology

Subterranean deposits of coal contain substantial quantities of entrained methane gas limited in production in use of methane gas from coal deposits has occurred for many years.

Substantial obstacles, however, have frustrated more extensive development and use of methane gas deposits in coal seams.

The foremost problem in producing methane gas from coal seams is that while coal seams may extend over large areas of up to several thousand acres, the coal seams are fairly shallow in depth, varying from a few inches to several meters.

Thus, while the coal seams are often relatively near the surface, vertical wells drilled into the coal deposits for obtaining methane gas can only drain a fairly small radius around the coal deposits.

Further, coal deposits are not amendable to pressure fracturing and other methods often used for increasing methane gas production from rock formations.

As a result, once the gas easily drained from a vertical well bore in a coal seam is produced, further production is limited in volume.

Such horizontal drilling techniques, however, require the use of a radiused well bore which presents difficulties in removing the entrained water from the coal seam.

The most efficient method for pumping water from a subterranean well, a sucker rod pump, does not work well in horizontal or radiused bores.

A further problem for surface production of gas from coal seams is the difficulty presented by under balanced drilling conditions caused by the porousness of the coal seam.

The drilling fluid exerts a hydrostatic pressure on the formation which, if it exceeds the hydrostatic pressure of the formation, can result in a loss of drilling fluid into the formation.

This results in entrainment of drilling finds in the formation, which tends to plug the pores, cracks, and fractures that are needed to produce the gas.

While the use of subterranean methods allows water to be easily removed from a coal seam and eliminates under balanced drilling conditions, they can only access a limited amount of the coal seams exposed by current mining operations.

The limitations of underground rigs limits the reach of such horizontal holes and thus the area that can be effectively drained.

In addition, the degasification of a next panel during mining of a current panel limits the time for degasification.

As a result, many horizontal bores must be drilled to remove the gas in a limited period of time.

Furthermore, in conditions of high gas content or migration of gas through a coal seam, mining may need to be halted or delayed until a next panel can be adequately degasified.

These production delays add to the expense associated with degasifying a coal seam.

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