Recycling centrifuge for the reduction of viscosity and gel strength of drilling fluids

• US 4,297,225 A
• Filed: 08/10/1978
• Issued: 10/27/1981
• Est. Priority Date: 09/30/1977
• Status: Expired due to Term

• Current Assignee: Bobby G. Hartley
• Original Assignee: Bobby G. Hartley
• Inventors: Hartley, Bobby G.
• Primary Examiner(s): Adee, John
• Application Number:
  US05/932,536
• Time in Patent Office: 1,174 Days
• Field of Search: 210/1, 210/19, 210/78, 210/811, 210/358, 210/360 R, 210/512 R, 210/520, 210/541, 210/542, 210/779, 210/788, 233/19 R
• US Class Current: 210/779
• CPC Class Codes: B04B 1/02 without inserted separating walls
• CPC Class Codes: B04B 5/00 Other centrifuges
• CPC Class Codes: B04B 5/10 Centrifuges combined with other apparatus, e.g. electrostatic separators; Sets or systems of several centrifuges B04B5/12 takes precedence; magnetic or electrostatic separators B03C; amassing particles by electric fields, e.g. by agglomeration B03C3/0175
• CPC Class Codes: E21B 21/06 Arrangements for treating drilling fluids outside the borehole

Abstract

The invention relates to process and apparatus for reducing the viscosity and gel strength of drilling fluids, or muds, without any necessity of introducing additives, or chemicals, into the mud. It embodies, in particular, (i) a process wherein a hydratable clay containing drilling fluid, or mud, is contacted with a revolving, or otherwise moving, surface at an angle of contact sufficient to impart adequate compression or sheer force, or both, to dewater the hydrated clay constituent, or constituents, of said drilling fluid, or mud; and (ii) an apparatus, or inertial device, constituted generally of structure inclusive of a revolvable cone within the inner surface of which a stream or spray of said hydratable clay-containing drilling fluid, or mud, can be impinged or contacted, when the cone is revolved at sufficient speed, to impart adequate compression or sheer force, or both, to dewater the hydrated clay constituent, or constituents, and thereby reduce the viscosity and gel strength of the drilling fluid, or mud.

Claims

1. A process for reducing the viscosity and gel strength of a hydratable clay containing drilling mud which comprises contacting said mud with the inner surface of a revolving cone, the total included angle of the cone ranging from about 40°

to about 120°

, the cone revolving at a speed ranging from about 400 to about 6000 revolutions per minute, sufficient to impart adequate compression force to dewater the hydrated clay constituent and thereby reduce the viscosity and gel strength of said mud.

2. The process of claim 1 wherein the total included angle of the inner surface of the revolving cone ranges from about 60°

to about 90°

.

3. An apparatus for reducing the viscosity and gel strength of a hydratable clay containing drilling mud which comprises

a cone provided with a small end and a large open end, the small end of the cone is enclosed and affixed upon an axle the central axis of which is common with the central axis of the axle, and the axle is journalled within the alternately disposed walls of a housing, the wall of the cone defining an inner surface which diverges to provide an included angle ranging from about 40°

to about 120°

,

a motor operatively engaged to the axle for rotation of said axle and cone,

a mud supply line aligned upon the inner surface within the large open end of the cone whereby a stream of mud can be injected into the inner surface of the cone, and wherein

the large open end of the cone is provided with a baffle of slightly less diameter than the diameter of the large open end of the cone and the mud supply line is extended through said baffle into the large open end of the cone, the housing is provided with enclosing walls defining an enclosed chamber, the chamber is provided with an outlet which is communicated with a mud collection tank, a recycle line communicates the tank with the mud supply line, and the motor recycles all or a portion of the mud from the tank through the mud inlet line to the large open end of the cone, whereby mud of reduced viscosity and gel strength can be discharged from the large open end revolving cone via the annular opening between the baffle and large open end of the cone into the chamber formed within the housing, and then discharged via the outlet from the chamber into the mud collection tank.

4. In apparatus for reducing the viscosity and gel strength of a hydratable clay containing drilling mud, the combination which comprises

a recycling centrifuge which includes

a vessel provided with an enclosing side wall and end walls,

a cone provided with a small end and a large open end, the large end of the cone having an inner surface which diverges to provide an included angle ranging from about 40°

to about 120°

, the small end of which is affixed upon an axle the central axis of which is in common alignment with the central axis of said cone, and the axle is journalled in the alternately disposed end walls of said vessel,

a mud supply line extending through an end wall of said vessel and aligned upon the inner surface within the large open end of the cone for delivery and injection of said drilling mud into the inner surface of said cone,

motor means for rotating said cone at a rate ranging from about 400 to about 6000 revolutions per minute sufficient to impart adequate centrifugal force and impact to dewater the hydrated clay constituent and thereby reduce the viscosity and gel strength of the mud,

an outlet in a wall of said vessel for the discharge of a drilling mud from the revolving cone after impact therewith whereby the viscosity and gel strength of the mud are reduced,

a tank provided with enclosing side wall and bottom within

which drilling mud can be contained, and atop which said recycling centrifuge is mounted, said tank including

a mud supply conduit extending from the bottom of said tank, and

a pump to the inlet side of which said mud supply conduit from the bottom of said tank is connected, the outlet side of said pump being connected to the mud supply line which is extended through an end wall of said vessel of the recycling centrifuge whereby drilling mud can be pumped from the bottom of said tank to the cone of the recycling centrifuge and the hydrated clay constituent dewatered to reduce the viscosity and gel strength of the mud, and the mud then discharged from the recycling centrifuge into the tank.

5. The apparatus of claim 4 wherein the total included angle formed by the opposed surfaces within the mouth of the cone ranges from about 60°

to about 90°

.

6. The apparatus of claim 4 wherein the large open end of the cone ranges up to about 18 inches in diameter.

7. The apparatus of claim 4 wherein the open end of the cone is provided with a baffle of slightly less diameter than the diameter of the open end of the cone, the large open end of the cone ranges up to about 18 inches in diameter, and the mud inlet line is extended through said baffle.

8. The apparatus of claim 7 wherein the diameter of the large open end of the cone ranges from about 9 inches to about 15 inches in diameter, and the motor means is capable of driving the cone at speeds of from about 2500 rpm to about 4500 rpm.