Claims
- 1. In a well drilling or servicing fluid for use in producing formations and which deposits filter cake therein containing water, a density increasing water soluble salt, a fluid loss control agent, a hydratable polymer solids suspending agent and a particulate solid bridging agent, the improvement wherein said particulate solid bridging agent consists essentially of an inorganic compound which is dissolvable by a clean-up solution comprised of water and an ammonium salt, said inorganic compound selected from the group consisting of metal sulfates, metal tungstates, metal fluorides, metal phosphates, metal peroxides, metal fluosilicates, and metal oxides, said metal oxides being selected from the group consisting of magnesium oxide, calcium oxide, lanthanum oxide, cupric oxide and zinc oxide.
- 2. The fluid of claim 1 which further comprises an oxidizer or other breaker which is activated by said ammonium salt in said clean-up solution to oxidize and break-up polymer in said filter cake deposited by said fluid.
- 3. The fluid of claim 2 wherein said oxidizer or other breaker is selected from the group consisting of magnesium peroxide, magnesium peroxydiphosphate, strontium peroxide, barium peroxide, calcium peroxide, magnesium perborate, barium bromate and mixtures thereof.
- 4. The fluid of claim 2 wherein said oxidizer or other breaker is magnesium peroxide.
- 5. The fluid of claim 1 wherein said density increasing water soluble salt is selected from the group consisting of sodium chloride, sodium bromide, sodium acetate, sodium formate, sodium citrate, potassium chloride, calcium chloride, calcium bromide and mixtures thereof.
- 6. The fluid of claim 1 wherein said fluid loss control agent is selected from the group consisting of starch, starch ether derivatives, hydroxyethylcellulose, cross-linked hydroxyethylcellulose and mixtures thereof.
- 7. The fluid of claim 1 wherein said hydratable polymer solids suspending agent is selected from the group consisting of xanthan, succinoglycon, cellulose derivatives, guar, guar derivatives and mixtures thereof.
Parent Case Info
This application is a divisional of U.S. application Ser. No. 09/629,959, filed Aug. 1, 2000, now U.S. Pat. No. 6,422,314.
US Referenced Citations (11)
Number |
Name |
Date |
Kind |
5238065 |
Mondshine et al. |
Aug 1993 |
A |
5607905 |
Dobson et al. |
Mar 1997 |
A |
5728654 |
Dobson et al. |
Mar 1998 |
A |
5783526 |
Dobson et al. |
Jul 1998 |
A |
5783527 |
Dobson, Jr. et al. |
Jul 1998 |
A |
5804535 |
Dobson et al. |
Sep 1998 |
A |
6143698 |
Murphey et al. |
Nov 2000 |
A |
6248698 |
Mullen et al. |
Jun 2001 |
B1 |
6300286 |
Dobson et al. |
Oct 2001 |
B1 |
6422314 |
Todd et al. |
Jul 2002 |
B1 |
6494263 |
Todd |
Dec 2002 |
B2 |
Foreign Referenced Citations (1)
Number |
Date |
Country |
0672740 |
Sep 1995 |
EP |