MUD LIFT PUMP FOR DUAL DRILL STRING
A mud lift pump for a dual drill string includes an energy input and an energy output in fluid communication with a fluid return flow passage in the dual drill string.
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BACKGROUNDThe invention relates generally to the field of dual drill pipe strings. More specifically, the invention relates to mud lift pumps that can form part of a dual drill string.
It is known in the art of subsurface wellbore drilling to use a single pipe string, two parallel pipes or two nested or concentric pipe strings. Concentric or nested pipe strings refer to a string consisting of inner pipe joints arranged within outer pipe joints connected end to end.
In concentric or nested drill strings, the inner pipe forms part of a flow bore extending from the surface to a drill bit at the lower end of the drill string. An annulus between the outer pipe and inner pipe forms part of a second flow bore extending from the surface to the drill bit.
The term “drilling” as used herein should be understood to refer to creation of a hole in the subsurface by means of the pipe string. It particularly applies for drilling in the crust of the earth for petroleum recovery, tunnels, canals or for recovery of geothermal energy, both offshore and onshore.
It is also known in the art to control pressure in the wellbore annulus (the annular space between the drill string and the wall of the wellbore by using a pump to lift the returning drilling fluid U.S. Pat. No. 7,913,764 issued to Smith et al. discloses a type of mud lift pump that may be used with conventional single conduit drill strings. Mud lift pumps may be operated to maintain a selected pressure or equivalent circulating density (ECD) in the wellbore.
What is needed is a mud lift (fluid return) pump for use with a dual drill string.
SUMMARYOne aspect of the disclosure is a mud lift pump for a dual drill string. The mud lift pump for a dual drill string includes an energy in the dual drill string and an energy output in fluid communication with a fluid return flow passage in the dual drill string.
A method for controlling pressure in a wellbore having a dual drill string therein includes pumping fluid through a fluid supply passage in the dual drill string. A pump energy input is operated using energy supplied through the dual drill string. The pumped fluid is discharged into the wellbore. Energy is imparted to fluid returned into a fluid return passage in the dual drill string from the wellbore using an energy output of the pump.
Other aspects and advantages of the invention will be apparent from the description and claims which follow.
In
In the example shown in
The dual drill string 1 is typically arranged with a flow diverter 6 at a lower end thereof connected to a bottom hole assembly (BHA) 8 holding the bit 7 at a lower end portion of the drill string. The bottom hole assembly (BHA) 8 may be a standard type BHA that can be used with conventional (single flow bore) drill pipe and drilling tools, including, without limitation, hydraulic (mud) motors, drill collars, measurement and/or logging while drilling tools. The flow diverter 6 has a flow passage assembly 10a providing a fluid connection between the fluid supply flow passage 4 of the dual drill string 1 and a channel 14 or channel assembly of the BHA 8. The channel 14 of the BHA 8 is shown in the example of
From the drill bit 7, the return fluid flow B moves in the well annulus 9 into a return flow passage assembly 10b arranged in the flow diverter 6. The axial cross section of a return flow passage assembly 10b also has a Y shape with second diverging branches 41 opening at one end into the well annulus 9 and an axial passage part 40 connected with the fluid return flow passage 5. The return flow B enters the inlet of the flow diverter return flow passage 10b and returns in the fluid return flow passage 5 of the dual string 1.
The dual drill string 1 may be arranged, for example, with one to four valve elements. Two of the valve elements may be arranged for closing and opening of the fluid supply flow A, and two of the valve elements may be arranged for closing and opening of the fluid return flow B. By such arrangement of valve elements, a double barrier system may be provided both for the control of the fluid supply flow A and for control of the fluid return flow B. The closing of the valve elements may be performed, in some examples automatically if the drilling system needs to close down, and in case of emergency, for example, a kick or other unwanted well fluid control conditions.
In
Another example of a pump 62 is shown in
Another example of a pump is shown in
In the present example, the first turbine 70 and the second turbine 66 may be magnetically coupled so that rotation of the first turbine 70 causes corresponding rotation of the second turbine 66. Magnetic coupling between the first and second turbines may be direct or may include any form of magnetic gearing to change the ratio of rotational speeds of the first and second turbines. Example magnetic gear arrangements are shown in U.S. Patent Application Publication No. 2010/0032952 filed by Hatch et al. Energy of the pumped fluid in the fluid supply flow path (4 in
In the present example, if magnetic coupling is used to transfer rotational energy from the first turbine 70 to the second turbine 66, it is preferable that the inner pipe 3A be made from a non-magnetic material. More preferably, the inner pipe may be made from a non-magnetic and electrically non-conductive material such as ceramic or certain compositions of glass, or fiber reinforced plastic. By using such material, magnetic coupling will be made effective between the turbines, and will result in low eddy current generation by reason of rotation of magnets (not shown) that couple rotation of the first turbine 70 to the second turbine 66. An inner pipe made from such materials may be covered by a thin layer of non-magnetic metal, such as monel or various alloys sold under the trademark INCONEL, which is a registered trademark of Huntington Alloys Corporation, Huntington, W. Va. A possible structure for a metal covered, ceramic or glass pipe structure is shown in U.S. Patent Application Publication No. 2011/0234035 filed by Wittschier.
If required, more than one of the pumps shown in
The foregoing example of a dual drill string, in which an inner pipe is nested within an outer pipe is not a limitation on the scope of the present disclosure. In other examples, the pipes may be side by side. In still other examples, the pipe may be a dual conduit coiled tubing. An example of such coiled tubing is described in U.S. Pat. No. 5,285,204 issued to Sas-Jaworsky. The pipe may also include one or more electrical conductors, for example, as described in U.S. Patent Application Publication No. 2012/0125686 filed by Hogseth et al.
For purposes of describing the function of the various forms of pumps that may be used with a dual drill string according to the disclosure, the pump may be generally described as having an energy input from any source, including a device in fluid communication with the fluid flow supply passage or electrical power, and an energy output in fluid communication with the fluid flow return passage, such that energy is transferred from the energy input to the fluid return flow. For example, the motor shown in
While the invention has been described with respect to a limited number of embodiments, those skilled in the art, having benefit of this disclosure, will appreciate that other embodiments can be devised which do not depart from the scope of the invention as disclosed herein. Accordingly, the scope of the invention should be limited only by the attached claims.
Claims
1. A mud lift pump for a dual drill string, comprising:
- an energy input in communication with a power source in the dual drill string; and
- an energy output in fluid communication with a fluid return flow passage in the dual drill string.
2. The mud lift pump of claim 1 wherein the dual drill string comprises nested conduits, the energy input accepts power from a fluid supply flow passage in an annular space between an outer pipe and an inner pipe, and the fluid return flow passage is in an interior of the inner pipe.
3. The mud lift pump of claim 2 further comprising a flow crossover, a motor disposed in a fluid discharge side of the flow crossover and a pump disposed in a fluid return side of the flow crossover, the motor and pump rotationally coupled to each other.
4. The mud lift pump of claim 2 wherein the pump is disposed in a segment of the nested conduit, the pump comprising a nozzle in fluid communication with the fluid supply flow passage and having an outlet disposed proximate an eductor disposed inside the inner pipe.
5. The mud lift pump of claim 2 wherein the pump comprises a first turbine rotatably in the annular space between the inner pipe and an outer pipe of a segment of the nested conduit and a second turbine rotatably inside the inner pipe.
6. The mud lift pump of claim 5 wherein the first turbine and the second turbine are rotationally magnetically coupled.
7. The mud lift pump of claim 6 wherein the inner pipe comprises a non-magnetic material.
8. The mud lit pump of claim 7 wherein the non-magnetic material is electrically non-conductive.
9. The mud lift pump of claim 1 wherein the energy input comprises an electric motor.
10. A method for controlling pressure in a wellbore having a dual drill string therein, the method comprising:
- pumping fluid through a fluid supply passage in the dual drill string;
- driving a pump energy input using power transmitted along the dual drill string;
- discharging the pumped fluid into the wellbore;
- imparting energy to fluid returned into a fluid return passage in the dual drill string from the wellbore using an energy output of the pump.
11. The method of claim 10 wherein the driving a pump energy input comprises passing the pumped fluid through a fluid-driven motor.
12. The method of claim 11 wherein the motor comprises at least one of a turbine and a positive displacement motor.
13. The method of claim 10 wherein the driving a pump energy input comprises discharging fluid from the fluid supply passage into a nozzle proximate an educator disposed in the fluid return passage.
14. The method of claim 13 wherein the imparting energy comprises increasing velocity of fluid in the fluid return passage by passing the returned fluid and fluid discharged from the nozzle through the educator.
15. The method of claim 10 wherein characteristics of the pump energy input, the pump energy output, a density of the pumped fluid and a flow rate of the pumped fluid are selected to provide a selected pressure in the wellbore.
16. The method of claim 15 wherein the selected pressure provides a selected equivalent circulating density of drilling fluid in a wellbore.
17. The method of claim 10 wherein the driving a pump energy input comprises rotating a first turbine, and the imparting energy comprises rotating a second turbine rotationally coupled to the first turbine.
18. The method of claim 10 wherein the driving a pump energy input comprises operating an electric motor using electric power transmitted along the dual drill string.
Type: Application
Filed: Jul 29, 2013
Publication Date: Jan 29, 2015
Applicant: Reelwell, A. S. (Royneberg)
Inventors: Ola M. Vestavik (Fosnavag), Harald Syse (Royneberg)
Application Number: 13/952,703
International Classification: E21B 21/08 (20060101);