Boring or penetrating the earth – Processes – Boring with specific fluid
Reexamination Certificate
2001-10-24
2003-12-16
Neuder, William (Department: 3672)
Boring or penetrating the earth
Processes
Boring with specific fluid
C175S071000, C166S305100
Reexamination Certificate
active
06662885
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to a method and an apparatus for producing a stream of pressurized substantially inert gas, and in one particular embodiment to a method and an apparatus for producing a stream of pressurized substantially inert gas for use in drilling wells through hydrocarbon formations.
BACKGROUND OF THE INVENTION
A stream of readily available, inexpensive and substantially inert gas is often required for a variety of different industrial applications. In this context the term substantially inert is used to generally describe gases with little or no appreciable free oxygen content. Such gases may contain varying amounts of hydrocarbons and other compounds and are for that reason not be truly inert, however, for the intended applications described below if a gas contains little or no appreciable free oxygen it will be considered to be substantially inert.
One such industry that requires a source of substantially inert gas is the petroleum industry. In oil drilling and production, substantially inert gases are often required for purposes of drilling, reservoir pressure maintenance, and for purging systems. For example, when drilling an oil or gas well, drilling fluids are often required to be circulated from the surface down through the drill string to the drill bit and back up to the surface again. The function of the drilling fluids is largely to control subsurface pressures, to carry away cuttings and other debris from the bottom of the well bore, and to eventually flush the cuttings from the well. In some instances the drilling fluids may also be used to “power” a downhole motor used to drive a drill bit. In certain types of drilling, and most notably underbalanced drilling, relatively low density drilling fluids that have densities generally less than water are utilized. In many such instances the low density fluids are comprised of gases. To minimize potential fire, explosion, and corrosion problems, ideally such gases are substantially inert.
Historically inert gases (for example nitrogen) that are required for use in drilling operations have been transported to drilling sites in sealed pressure vessels. However, due to the transportation costs associated with bringing large volumes of inert gas to a remote oil or gas drilling site, a practice has developed wherein the exhaust gas stream from an internal combustion engine is utilized as a source of substantially inert gas. In such applications exhaust gases from the internal combustion engine are typically collected, cooled, deacidified if necessary, and then directed to a compressor where their pressure is increased prior to being injected into a well. Provided that the internal combustion engine operates at a high enough level of efficiency there will be either no oxygen in the exhaust or only a relatively minor amount of oxygen present.
While the exhaust stream from an internal combustion engine provides a somewhat convenient and readily accessible supply of substantially inert gas, an inherent problem that arises when utilizing exhaust gas as a feed source for a compressor is that the compressor will typically have a higher capable throughput than the volume of exhaust gas that can be created by the engine. Where there is insufficient exhaust to feed the compressor, a vacuum will tend to form within the intake manifold. This vacuum in turn has a tendency of drawing atmospheric air into the system. If atmospheric air is allowed to enter the gas stream the percentage of oxygen in the gas injected into the well increases, thereby increasing the possibility of an explosion or fire, and increasing the likelihood of corrosion.
To combat this problem others have tried to direct the output from other unrelated internal combustion engines (for example nearby generator sets, etc.) into the feed stream of the compressor to balance the available exhaust gas stream with the compressor's input. Unfortunately the amount of unrelated exhaust gas readily available is rarely sufficient. Still others have connected hydraulic or mechanical brakes, generators or other devices to the internal combustion engine in an attempt to force it to operate under an enhanced load situation so as to generate excess exhaust. While such attempts have had limited success under specific circumstances, they add mechanical complexity, expense, and a further source for mechanical breakdown.
SUMMARY OF THE INVENTION
The invention therefore provides a method and apparatus for producing a stream of substantially inert gas from an internal combustion engine that provides a means of effectively increasing the load on the engine to enhance exhaust gas production, while simultaneously providing sufficient intake gas to meet the needs of a compressor or bank of compressors. The invention accomplishes this result without the need to utilize the exhaust gases from unrelated internal combustion engines, and without the addition of complex and costly mechanical structures. The invention also provides for the establishment and the maintenance of a positive gas pressure within the compressor intake manifold to limit the ingress of atmospheric air into the compressor system.
Accordingly, in one of its aspects the invention provides a method of producing a pressurized stream of substantially inert gas, the method comprising collecting the exhaust gases from an internal combustion engine; directing said exhaust gases into the intake of a compressor, said compressor compressing said exhaust gases to a desired pressure; and, recirculating a portion of said compressed exhaust gases back to said intake of said compressor such that the pressure of said exhaust gases within said compressor intake is maintained above atmospheric pressure.
In a further aspect the invention provides an apparatus for producing a pressurized stream of substantially inert gas, the apparatus comprising a compressor having an intake manifold and an output manifold, said intake manifold receiving the output exhaust gas stream from an internal combustion engine; and, a compressed gas re-circulation conduit connecting said output manifold to said intake manifold such that a portion of the pressurized gas from said compressor is re-circulated from said output manifold back to said intake manifold to maintain the gas pressure within said intake manifold above atmospheric pressure.
Further advantages of the invention will become apparent from the following description taken together with the accompanying drawings.
REFERENCES:
patent: 3815673 (1974-06-01), Bruce et al.
patent: 4136747 (1979-01-01), Mallory
patent: 4350505 (1982-09-01), Mallory
patent: 5273344 (1993-12-01), Volkwein
patent: 5412940 (1995-05-01), Baugh
patent: 5607903 (1997-03-01), Bastos
patent: 5663121 (1997-09-01), Moody
patent: 6032747 (2000-03-01), Moody et al.
Merek & Blackmon & Voorhees, LLC
Neuder William
Precision Drilling Technology Services Group Inc.
Smith Matthew J
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