Earth boring – well treating – and oil field chemistry – Earth boring – Contains organic component
Patent
1998-02-24
2000-02-01
Tucker, Philip
Earth boring, well treating, and oil field chemistry
Earth boring
Contains organic component
507118, 507119, C09K 702
Patent
active
060202890
DESCRIPTION:
BRIEF SUMMARY
This invention relates to novel aqueous drilling fluids comprising particular classes of polymer which act as inhibitors of shale disintegration or swelling ("shale inhibitors") during the drilling of wells. It also relates to processes of using the drilling fluids and minimising shale disintegration. The polymers are also useful for inhibiting clay swelling, disintegration or dispersion within fluids used for oil or gas reservoir treatment and permeation.
It is known to use aqueous based fluids in drilling processes to carry rock materials out of the drilled well. When drilling is carried out in a formation formed from the minerals known as shales major problems can result from interaction of water in the drilling fluid with the shale. Water tends to become absorbed into the shale which is caused to swell or weaken, thus disrupting its internal structure. This can lead to contraction of the wellbore and softening and disintegration of the wall of the well shaft. This in itself is problematic. Furthermore, parts of the rock may become detached from the wall of the well and increase the viscosity and solids content of the drilling fluid passing through the well. Use of oil-based drilling fluids would alleviate these problems, but such fluids tend to be expensive and are thought of as environmentally undesirable. Therefore methods have been sought for inhibition of shale disintegration ("shale inhibition") when using aqueous drilling fluids.
Similar problems occur with swelling and disintegration of clay materials within oil- and gas-bearing reservoirs on contact with aqueous reservoir fluids. Such swelling tends to lead to permeability problems within these reservoirs. Therefore it is also desired to provide methods of inhibiting disintegration of clay ("clay inhibition") in such environments.
It is known to incorporate various polymeric materials into drilling fluids for various purposes. These various polymeric materials are directed to a range of problems which may be encountered during drilling, depending upon the rock type in which drilling is taking place. In general, if it is known, from prior analysis or from past experience, that a particular rock will give a particular problem, such as shale or clay disintegration, then suitable additives are included in the drilling fluid in order to prevent such problems or alleviate them if they arise. Alternatively, if it is not known which problems are likely to arise, drilling is usually begun with a simple basic drilling fluid. If problems are observed to arise during drilling appropriate additives are then included in the fluid. Therefore if it is observed that the shale or clay disintegration is occurring, a shale or clay inhibitor is added to the fluid.
Various polymeric materials are known for incorporation into drilling fluids as shale inhibitors. High molecular weight (5 to 15 million daltons) polyacrylamides and acrylamide/acrylate copolymers (anionic polyacrylamides)are known for this purpose. They are believed to work by absorbing onto the shale, coating it and preventing penetration by water. However, it is common to incorporate bentonite as a component of drilling fluids as a viscosifier. Polyacrylamides, in particular anionic polyacrylamides, tend to absorb onto the surface of bentonite in the drilling fluid and portions of the polymer dose are lost.
U.S. Pat. No. 4,440,649 suggest the use of a vinyl amide-vinyl sulphonate terpolymer with acrylamide for the prevention of disintegration of clay-containing materials. The terpolymer suggested is described in U.S. Pat. No. 4,309,523. All of the exemplified polymers contain 2-acrylamide-2-methyl-propane-3-sulphonic acid (AMPS). Amounts of AMPS are often very high, for instance at least 50 wt %, often at least 65 wt %. The vinyl amide used is N-vinyl-N-methyl-acetamide, vinyl acetamide or vinyl formamide. These monomers are generally present in minor amounts in the exemplified polymers, in particular never more than 50 wt % of the polymer. When such monomers are present in amounts of 50% it is always
REFERENCES:
patent: 3296126 (1967-01-01), Diener et al.
patent: 3323603 (1967-06-01), Lummus et al.
patent: 4500437 (1985-02-01), Engelhardt et al.
patent: 4554081 (1985-11-01), Borchardt et al.
patent: 4757862 (1988-07-01), Naiman et al.
patent: 4804793 (1989-02-01), Lai et al.
patent: 4921621 (1990-05-01), Costello et al.
patent: 4988450 (1991-01-01), Wingrave et al.
Ciba Specialty Chemicals Water Treatments Limited
Crichton David R.
Tucker Philip
LandOfFree
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