METHOD AND COMPOSITION FOR DRILLING AND CEMENTING OF WELLS

• US 3,557,876 A
• Filed: 04/10/1969
• Issued: 01/26/1971
• Est. Priority Date: 04/10/1969
• Status: Expired due to Term

• Current Assignee: Art Tragesser
• Original Assignee: Art Tragesser
• Inventors: Tragesser, Art
• Application Number:
  US04/815,221
• Time in Patent Office: 656 Days
• US Class Current: 166/292
• CPC Class Codes: C09K 8/05 containing inorganic compounds only, e.g. mixtures of clay and salt

Abstract

A drilling fluid for oil and gas wells which can be converted to a cementitious material suitable in well-cementing operations. The preferred drilling fluid has a water base and contains pozzolan and sufficient colloidal clay to form a thin but effective filter cake on the walls of the borehole during the drilling operation. When desired, an alkaline earth hydroxide, such as calcium hydroxide, is introduced into the drilling fluid to form a cementitious material for use in the borehole, for example, for cementing the casing in the borehole.

Claims

2. The method of claim 1 wherein said alkaline earth hydroxide comprises calcium hydroxide.

3. A drilling and cementing method comprising:

a. drilling a borehole in the earth'"'"''"'"'s surface and circulating through said borehole during said drilling a drilling fluid containing water and from about 55 to about 95 weight percent alkaline earth hydroxide;

b. thereafter adding sufficient pozzolan to said drilling fluid to form a cementitious material; and

c. introducing said cementitious material into said borehole.

4. The method of claim 3 wherein said alkaline earth hydroxide comprises calcium hydroxide.

5. A drilling and cementing method comprising:

a. drilling a borehole in the earth'"'"''"'"'s surface and circulating through said borehole during said drilling a drilling fluid containing from about 35 to about 80 weight percent pozzolan;

b. thereafter adding sufficient alkaline earth hydroxide to said drilling fluid to form a cementitious material; and

c. introducing said cementitious material into said borehole.

6. The method of claim 5 wherein said alkaline earth hydroxide comprises calcium hydroxide.

7. The method of claim 5 wherein said cementitious material is introduced into a porous formation communicating with said borehole.

8. The method of claim 5 wherein said drilling fluid further comprises a colloidal clay, and wherein said circulation causes a filter cake comprising said colloidal clay and pozzolan to be formed on the walls of said borehole so that the addition of said alkaline earth hydroxide to said drilling fluid, upon contact with said filter cake forms a cementitious material of said filter cake.

9. An aqueous drilling fluid which is settable by the addition of an alkaline earth hydroxide thereto, consisting essentially of from 40 to 80 weight percent water, from about 3 to about 8 weight percent of colloidal clay, and from about 35 to about 80 weight percent pozzolan.

10. The drilling fluid of claim 9 wherein said colloidal clay is selected from bentonite and attapulgite.