Wells – Processes – Separating material entering well
Reexamination Certificate
2000-01-27
2001-08-07
Tsay, Frank (Department: 3672)
Wells
Processes
Separating material entering well
C166S105500
Reexamination Certificate
active
06269880
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to a system for removing solids from a well bore and reclaiming the well bore fluid. More particularly, but not by way of limitation, this invention relates to a system and method for removing solids from an oil and gas well bore utilizing a work string, and thereafter, reclaiming the well bore fluid.
In the oil and gas industry, a well is drilled and completed to a hydrocarbon bearing zone from which hydrocarbons are produced. During the life of the well, sand is many times produced from the reservoirs. The sand can build up within the well bore as is well understood by those of ordinary skill in the art.
Operators have found it necessary to remove the sand, debris and other solids that accumulates within the well bore. The sand can cause numerous operational problems, some of which may result in hazardous and/or dangerous conditions. Hence, the sand, debris and other solids require removal.
In the past, operators have run a work string within the well bore in order to wash out the sand and debris. Work strings include coiled tubing, snubbing pipe, drill strings, and other tubulars. One of the problems faced by such an operation includes contamination of the well bore fluid with the sand, debris and other solids. After completion of the wash operation, the well bore fluid has to be separated.
Well bore fluids have become quite sophisticated over the years. As those of ordinary skill in the art will recognize, compatible well bore fluids must be placed into the wells in order to enhance production, decrease corrosion and increase reservoir life. The well bore fluids can become quite costly, and therefore, conservation of the fluids is advantageous. Examples of well bore fluids include, but certainly not limited to, brine, zinc chloride, barite, etc.
The prior art systems of separating, cleaning, and/or reclaiming the well bore fluids have proved to be costly and inefficient. For instance, sock filters have been utilized to filter out the solids. However, the filters become clogged quickly. Further, it is a time consuming practice to exchange dirty filters with clean filters.
Additionally, most of the solid removal operations occur on platforms, semi-ssubmersibles, jack-ups, etc that contain drilling rigs. Therefore, the systems use a cumbersome assembly of shale shakers, settling tanks and charger pumps that are generally associated with drilling systems. These prior art systems take up space, cost significant sums of money and are inefficient.
Presently, the well bore fluid with entrained solids is directed through a shale shaker. Underneath the shale shacker is a settling tank. The well bore fluid is then directed to a centrifuge via a charger pump. Thereafter, the well bore fluid is directed to a main tank. The well bore fluid is then pumped backed into the well bore from this main tank. This is a cumbersome and expense system.
Therefore, there is a need for a system for removing solids from a well bore that takes up a minimum of space and is economical. Further, there is a need for a method of utilizing a work string to clean out sand and debris, and thereafter, reclaim the well bore fluid for further use. There is also a need for a method for reclaiming well bore fluids such as brine when the brine is used to clean out a well bore with a coiled tubing string. These and many other needs will be met by the invention herein disclosed.
SUMMARY OF THE INVENTION
A system for removing solids from a well bore and reclaiming the well bore fluid is disclosed. A work string will be disposed therein. In the preferred embodiment, the well bore will have a coiled tubing string or snubbing pipe concentrically disposed therein. In the most preferred embodiment, the work string is coiled tubing. The system comprises a return line for receiving a well bore stream from the well bore. The well bore stream contains solids, a gas component and a water component.
The system also includes a gas separator means, connected to the return line, for separating the gas component from the remainder of the well bore stream, and wherein the separator means has a first outlet for exiting the gas component and a second outlet for exiting the remainder of the well bore stream. Also included is a solids separator means, connected to the second outlet, for separating the remainder of the well bore stream into a first stream containing the solids and a second stream containing the remainder of the well bore stream, and wherein the solids separator means contains a first exit for exiting the solids and a second exit for exiting the remainder of the stream. The solids separator will be located longitudinally below the gas separator so that a hydrostatic head pressure feeds the well bore fluid to the solids separator.
The system further includes a cuttings box connected to the first exit of the solids separator, with the cuttings box being configured to receive the solids from the solids separator means. The system may further contain a fluid tank connected to the second exit of the solids separator, with the fluid tank configured to receive the remainder of the well bore stream. In the preferred embodiment, measuring means, operatively associated with the cuttings box, for measuring the quantity of solids disposed within the cuttings box will also be included.
In one of the embodiments disclosed, the solids separator means comprises a centrifuge separator. Additionally, the gas separator means comprises a two phase separator. In the preferred embodiment, the well bore fluid is a brine.
A method of removing sand from a well bore and reclaiming a well bore fluid is also disclosed. The well bore will intersect a hydrocarbon reservoir. The method comprises placing a coiled tubing string concentrically within the well bore, with the coiled tubing string forming an annulus therein. A fluid is circulated down the inner bore of the coiled tubing string; fluid exits the end of the coiled tubing string and the sand and debris entrains with the fluid. Additionally, gas from the hydrocarbon bearing reservoir may also entrain with the fluid. The fluid, along with the entrained sand, and entrained gas component mix with the well bore fluid. An oil component from the reservoir may also mix with the fluid. The pumping rate will provide for a back pressure on the return line.
The method further includes circulating the well bore fluid up the well bore annulus and then flowing the well bore fluid into a gas separator under pressure where the gas component is separated from the well bore fluid. Next, the solids are separated from the well bore fluid and the solids are collected in a collection tank. The method may further include measuring the solids in the collection tank and calculating the amount of sand removed from the well bore.
The step of separating the gas component may consist of flowing the well bore fluid to a two-phase separator, dividing the gas component from the well bore fluid, and flowing the well bore fluid to the separator means. In this step, the separator means is located longitudinally below the two-phase separator so that a hydrostatic head pressure is created and aids in flowing the well bore fluid to the separator means.
In the step of separating the solids, the method may include channeling the well bore fluid to a centrifuge separator where the solids are segregated from the well bore fluid. The method may further include recirculating the well bore fluid into the bore of the coiled tubing string. In yet another embodiment, the method may include a step of separating an oil component from the well bore fluid, and thereafter, recirculating the fluid in the well bore.
The fluid used in the well bore may be a variety of different fluids. In the preferred embodiment, the fluid consist of a brine based system. Other fluid systems include zinc chloride, barite based drilling fluid, seawater, etc.
An advantage of the present system includes the ability to reclaim the well bore fluid. Another advantage is that the solids removed from the well bore can be place
Domingue & Waddell PLC
Tsay Frank
LandOfFree
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