Patent Application
20050072570
The present invention relates to a contamination-resistant sand control apparatus and a method for preventing the contamination of sand control devices. More particularly, the present invention relates to an apparatus that controls sand flow and inhibits the formation and buildup of particulates on a surface of the sand control apparatus and a method for inhibiting the formation and buildup of particulates on a sand control device.
To prevent an influx of sand into production tubing, sand control devices, such as sand screens attached to the production tubing at desired production levels, are used to allow the flow of hydrocarbons and other fluids to proceed while preventing the flow of sand into the production tubing. A major problem that arises during fluid flow through the sand control devices, however, is the formation and buildup of unwanted materials on the surface of the sand control device as a result of substances found in the well fluids. Particulates of calcium carbonate, paraffin, and asphaltene, found in subterranean water, oil, and drilling fluids, can precipitate on the sand control device and impede hydrocarbon flow through the production tubing. Therefore, the removal and prevention of unwanted buildup and precipitation on sand control devices can be helpful and necessary to assure the uninhibited flow of hydrocarbons in the production tubing.
Current solutions to resist particulate buildup require that well production be shut down so that treatment chemicals can be pumped down the well. This process requires the treatment chemicals to soak into the well formation for two to three days, further suspending hydrocarbon production. In the event that particulate buildup has prohibitively blocked hydrocarbon flow, the sand control device needs to be decontaminated or cleaned of the blockage. Current solutions to decontaminate sand control devices involve pumping a corrosive fluid down the production tubing to dissolve any particulate buildup on the sand control device. These solutions, however, require that hydrocarbon production be shut down for two to three days and also require a workover of the production screen assembly. Furthermore, by the nature of pumping fluids into porous and permeable media, the accuracy of placement of treatments for contaminate removal is not perfect nor necessarily accurate.
Current preventative and decontamination measures must also be repeated approximately two times per year to resist restriction and clear flow into the sand control device. Therefore, current solutions are extremely expensive, time consuming, and resource intensive.
The present invention provides a method and apparatus for preventing the contamination of sand control devices, which meet the needs described above and overcome the deficiencies of the prior art.
In one embodiment, the present invention is directed to a method for preventing the contamination of sand control devices. The method involves placing time-release treatment chemicals in a flow channel that communicates with a surface of the sand control device.
In another embodiment, the present invention is directed to an apparatus wherein chemical inhibitors are placed in a flow channel by disposing them within, or adhering them to, the sand control device before the sand control device is placed into a production zone. Chemical inhibitors are known in the art and the type or types used is largely dependent on the contaminants (e.g., scale, paraffins, and asphaltene) present in the well. Preferably, a single or some combination of scale inhibitors, paraffin inhibitors, and asphaltene inhibitors are used. In another aspect of the present invention, other treatment chemicals such as enzymes, which break down and eliminate organic-based drilling muds and completion fluid may also be used.
In addition, a preferred embodiment for this method uses encapsulated chemistry. In one embodiment, the encapsulated time-release treatment chemicals are approximately 1 to 5 millimeters in size and placed inside of a prepacked screen. In another embodiment, the time-release treatment chemicals are coated onto the inner and outer surfaces of the sand screen.
Other and further objects, features and advantages of the present invention will be readily apparent to those skilled in the art upon a reading of the description of preferred embodiments which follows.
The present invention is better understood by reading the following description of non-limitative embodiments with reference to the attached drawings, which are briefly described as follows:
It is to be noted, however, that the appended drawings illustrate only typical embodiments of this invention and are therefore not to be considered limiting of its scope, as the invention may admit to other equally effective embodiments.
The details of the present invention will now be discussed with reference to the figures.
Preferably, the time-release treatment chemicals 60 are encapsulated and include any combination of one or more scale inhibitors, paraffin inhibitors, asphaltene inhibitors, breaker chemicals and the like. The scale inhibitors preferably include any combination of one or more phosphates and organic esters. The paraffin inhibitors preferably include any combination of one or more heavy aromatic naphtha, hapthenic distillates, C-20-C-28 Olefins and Trimethylbenzene. The asphaltene inhibitors preferably comprise Targon, commerically known as N-Tyrol. The breaker chemicals include enzymes. As hydrocarbons and other drilling fluids flow from subterranean formation 1 through the gravel pack 50 and encapsulated treatment chemicals 60 into the production tubing 40, the treatment chemicals are released into the flow channel that communicates with surfaces on the sand screen 10 and prevent and clear particulate buildup and formation.
In another embodiment of the present invention, at least one time-release treatment chemical is coated onto a surface 70 of the sand control device 10, as shown in
In accordance with the embodiment of
In yet another embodiment of the present invention, the sand control screen 10 is pre-packed with gravel 80, as shown in
As those of ordinary skill in the art will appreciate the present invention has application in devices other than sand control screens. Indeed, the present invention also has application on or in connection with slotted liners and any other physical devices placed downhole in wells that produce formation sand along with reservoir fluids.
Therefore, the present invention is well adapted to carry out the objects and attain the ends and advantages mentioned as well as those that are inherent therein. While numerous changes may be made by those skilled in the art, such changes are encompassed within the spirit of this invention as defined by the appended claims.
