Earth boring – well treating – and oil field chemistry – Well treating – Contains organic component
Patent
1995-11-28
1999-07-06
Kelly, C. H.
Earth boring, well treating, and oil field chemistry
Well treating
Contains organic component
507110, 507925, 507903, C09K 702, E21B 4327
Patent
active
059197390
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a plugging liquid on emulsion basis, a method for its preparation and a method for plugging a zone of a subterranean formation penetrated by a drill hole.
2. Description of the Background of the Invention
A large number of gel forming compositions are known in the art for use as well control liquids in the drilling of wells for the recovery of oil and gas, for instance in cases where well liquids are lost to the formation or liquid or gas is flowing into the well from the formation. It is known to use polysaccharides for thickening purposes in such known gel forming compositions, see e.g. Norwegian Patents Nos. 116,667 and 161,625, U.S. Pat. No. 4,634,538 and British Patent No. 1,406,513.
It is also known to utilize as plugging liquids so-called "rheotropic" liquids. These liquids thicken when subjected to high shear stress. The rheotropic liquid must have physical characteristics enabling it to be easily pumped through the mud system (Condition 1) to the drill bit when leakages occur in the formation. The shear stress created when the liquid is forced through the nozzles of the drill bit, where the pressure drop will be in the range of about 50 to 120 bars, must result in a thickening of the liquid (Condition 2). The time before thickening must however be sufficient for the liquid to flow into and seal the formation.
U.S. Pat. No. 4,663,366 (Carr Corporation) discloses a rheotropic liquid of such a nature and an emulsion technique for controlling the thickening of the liquid. According to said patent, a polycarboxylic acid-containing water-in-oil emulsion is used wherein: hydrophilic clay such as bentonite, and additionally contains a solubilized surfactant consisting of a polyamine derivative, and polycarboxylic acid.
It is critical that the bentonite be kept separated from the water until the required thickening of the liquid is initiated. For that purpose each droplet of the dispersed aqueous phase is coated with a membrane or a film of a polymeric material which is formed as a consequence of the aqueous phase being dispersed or emulsified in the oil phase of the emulsion. The film or membrane is formed as a result of the interfacial interaction between the polyamine derivative in the oil phase and the polyacrylamide and the polycarboxylic acid in the dispersed aqueous phase. When the emulsion is subjected to high shear forces, the protective film around the dispersed droplets in the emulsion is broken and the bentonite comes into contact with the water, thus enabling a swelling of the bentonite and consequently a thickening of the liquid. However, for the rheotropic liquid of U.S. Pat. No. 4,663,366 the obtainable ratio of the thickness of the liquid in Condition 2 to the thickness of the liquid in Condition 1 is lower than is desirable.
There is a need in well control operations for improved plugging liquids which (1) have the lowest possible viscosity in Condition 1, before they are subjected to high shear forces, (2) thickens to a high thickness in Condition 2 after having been subjected to high shear forces, (3) maintain their acquired thickness for a longer period of time, and (4) to the least possible extent undergo a thickening in Condition 1 as a result of the emulsion gradually deteriorating during storage or before it has had time to pass through the nozzles of the drill bit in the drill hole.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a plugging liquid exhibiting markedly improved properties compared to the plugging liquids that are available today.
Thus, the invention provides a new plugging liquid for plugging a zone of a subterranean formation around a drill hole, consisting of an aqueous liquid containing a polysaccharide. The plugging liquid is characterized in that it consists of an emulsion comprising:
Like the emulsion of U.S. Pat. No. 4,663,366 discussed above, the new emulsion makes use of an emulsion technique involving storing of reactants separately, one in each
REFERENCES:
patent: 3243000 (1966-03-01), Patton et al.
patent: 3741894 (1973-06-01), Storfer
patent: 3804760 (1974-04-01), Dorley
patent: 3979303 (1976-09-01), Kang et al.
patent: 4500437 (1985-02-01), Engelhardt et al.
patent: 4551513 (1985-11-01), Engelhardt et al.
patent: 4571422 (1986-02-01), Symes et al.
patent: 4663366 (1987-05-01), Drake et al.
patent: 4683953 (1987-08-01), Eustace et al.
patent: 5211859 (1993-05-01), Horton et al.
patent: 5407909 (1995-04-01), Goodhue, Jr. et al.
patent: 5663123 (1997-09-01), Goodhue, Jr. et al.
patent: 5717131 (1998-02-01), Sunde et al.
EP 251638 (1988) As Abstracted By Dewent 88:001492.
Johnsen Hans Konrad
Sunde Egil
Den Norske Stats Oljeselskap A.S.
Kelly C. H.
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