Earth boring – well treating – and oil field chemistry – Well treating – Contains organic component
Patent
1999-06-10
2000-12-26
Warden, Jill
Earth boring, well treating, and oil field chemistry
Well treating
Contains organic component
507234, 507927, 507928, 1663051, E21B 2106, E21B 4316
Patent
active
061659487
DESCRIPTION:
BRIEF SUMMARY
The invention relates to a process for drying out rock containing immobile formation water in the intake radius of natural gas wells and gas storage wells, in which water-repellent active compound in dispersed form renders the water-containing rock hydrophobic.
In the vicinity of production wells in natural gas fields, formation water in the pore cavities of the rock prevents the flow of gas to the production well. If the formation water has a high salt content, the evaporation of water causes the solubility limit to be exceeded, and in particular chloride salts crystallize out. Since salt water is continuously drawn into the pore cavities by capillary forces, the salt crystals constantly grow until the flow channels are closed to the point of impermeability to natural gas.
Salt deposits occur not only in the pore cavities, but also form on well casings and other pipes, and on storage and further processing facilities, such as piping, valves, heating coils and heating tubes and separators, which are involved with handling the gas produced and the formation water which is separated off. When a deposit forms, the extraction rate decreases and finally the entire operation ceases. Furthermore, the heat transfer is decreased.
The customary process for enhancing the productivity of natural gas wells is the hydraulic generation and stabilization of fractures in the vicinity of the well. The additional drainage areas produced by this means and the high gas flux density in the fractures leads to an elevated production rate of the well. However, this process is highly expensive. Fracture formation can be controlled only to a very restricted extent.
The salt deposits, in particular chloride salts, can be eliminated by flushing with fresh water. Since the salt deposits continue to reform, these flushing operations must be carried out at regular intervals, which causes frequent losses of production.
A process for removing salt deposits in wells is described in U.S. Pat. No. 5,051,197. There, the wells are treated with an aqueous composition of aminopolycarboxylic acid and water-soluble organosilane. However, water-soluble organosilanes generally have a high volatility and a low flashpoint, hydrolyze rapidly and release toxic and highly flammable products in the presence of water. Thus, chlorosilanes form HCl, methoxysilanes form methanol and ethoxysilanes form ethanol. Therefore, these compositions can only be kept for a short time and are difficult to handle. In addition, a process for removing salt deposits is described here, and not a process for preventing salt deposits.
A process for preventing salt deposits in wells is described in U.S. Pat. No. 3,682,831. There, the wells are treated with water-soluble glycol-silicone copolymers which contain SiOC bonds which are highly sensitive to hydrolysis. However, the action of this process is too poor.
U.S. Pat. No. 3,653,442 describes a process for removing water by means of micellar dispersions, which achieves the increase in gas or oil flow through removal of a water block.
Database WPI, week 9311, AN-93-091996 and SU-A-1 724 854 describe a seating material for natural gas and oil boreholes which is claimed to block mobile ingressing water.
U.S. Pat. No. 4,074,536 describes a process for hydrophobicizing rock formations using organosilicon compounds with regard to preparation of the rock and prevention of dissolution of the rock in the presence of water.
The object was therefore to provide a means which drys out immobile formation water in the rock and which provides durable prevention of salt deposits in the pore cavities of the rock in the vicinity of natural gas production wells in natural gas fields.
The water-repellent active compounds (A) used according to the invention are readily dispersible in the formation water and can therefore be distributed homogeneously over the entire rock surface and then break there. By this means, the water-repellent active compounds (A) cover the rock surface in a very thin layer.
If natural gas is then produced, decreasing the gas
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Burger Willibald
Dewenter Wendelin
Esterbauer Ludwig
Geck Michael
Sewe Kai-Udo
Cross LaToya I.
Wacker-Chemie GmbH
Warden Jill
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