Axial Oscillation Device
A downhole pressure pulsing apparatus comprising: an upper sub that comprises a tube having a hollow interior through which fluid can flow; a middle sub that comprises a tube having a hollow interior through which fluid can flow; a lower sub that comprises a tube having a hollow interior through which fluid can flow; wherein said upper sub is connected to said middle sub by a connection such that the hollow interior of said upper sub 1 is in fluid communication with said middle sub's hollow interior; wherein said middle sub is connected to said lower sub by a connection such that the hollow interior of said middle sub is in fluid communication with said lower sub's hollow interior; an impeller assembly, wherein said impeller assembly comprises an impeller that is rotatably mounted inside said middle sub's hollow interior; a stator, wherein said stator is housed inside said upper sub's hollow interior and wherein said stator directs fluid flow into said impeller; a cam assembly mounted within said lower sub's hollow interior; a restrictor assembly that varies total flow area in order to generate pressure pulses, wherein said restrictor assembly is mounted within said lower sub's hollow interior; and wherein said cam assembly converts rotational motion created by said impeller assembly to reciprocating axial motion within said restrictor assembly.
The invention relates generally to the oil and gas industry and more specifically to devices and methods to convert pressure pulses into axial movement of a drill string to reduce friction and drag. Downhole static and dynamic friction can exacerbate drag and weight stacking, whether using a rotary steerable or downhole motor assembly. Drag and weight stacking can lead to tool face control issues in slide drilling, low rate of penetration, high torque, premature buckling, extensive bit wear, short lateral sections, and difficulty in running subsequent casing strings.
There are multiple challenges involved within daily drilling operations on a global scale today that limit drilling efficiencies and increase lifting costs to the operator. Friction reduction technology has been used to reduce the negative effect of highly inter-bedded formations, ineffective weight transfer, low rate of penetration, sinusoidal and helical buckling, erratic reactive torque, poor tool face control, high tortuosity in extended reach wells and casing running, as well as objects becoming stuck in holes and needing to be fished out. An embodiment, in combination with a shock tool or sub, provides a means to reduce friction between a drill string and a formation or wellbore. Having the ability to reduce static friction negates most of the problems listed above that are widely seen in today's extended reach drilling operations around the globe.
SUMMARYAn embodiment comprises a tool placed within a drill string to create a pressure pulse within a drilling fluid system when drilling fluid is being pumped through the drill string, it then converts the pressure pulse into axial movement of the drill string using a shock tool or sub. A valve system in an embodiment alternates the total flow area thereby creating high and low pressure pulses. The shock tool or sub then transforms the pressure pulses into mechanical axial motion along the axis of the drill string to facilitate friction reduction in the wellbore thus allowing the operator to drill further, faster and with more confidence. Drive mechanisms such as positive displacement motors (PDM) and turbines are known in the industry. An embodiment can comprise an axial impeller that spins at high rpm. An embodiment can comprise a cam system that spins with the axial impeller and causes the valve system's rocket to axially reciprocate. Axial reciprocation of the rocket in a venturi then varies the total flow area and generates high and low pressure pulses. Alternating high and low pressure pulses act on the pump open area of a shock tool or sub to generate axial motion along the drill string. Various impeller designs allow the tool to work at different frequencies. Impeller variation enables operation with different types of measurement while drilling tools. Additionally, a bottom sub can be changed out to convert a standard tool to one having an on/off switch. This mechanism engages or disengages the orifice from the rocket as and when required through cycling a mud pump. An increase or decrease in standpipe pressure confirms the position of the tool.
Reduction of friction brings substantial and valuable improvements in the quality of drilling operation. A tool in accordance with an embodiment can change total flow area to create pressure pulses. Alternate high and low pressure pulses act on the pump open area of a shock tool or sub and cause a mandrel on a shock tool or sub to extend and retract at high frequency. A mandrel's axial motion will gently oscillate a drill string and reduce friction between a drill string and a formation. Mechanical axial motion of a shock tool or sub can overcome static friction between mechanically stuck objects.
A rocket holder can be threaded to the lower inner diameter thread of a barrel cam. A rocket can be linked to a rocket holder by threaded connection, such as a male thread on a rocket engaging a female thread on the rocket holder. A venturi is located in a lower sub's hollow interior. When a rocket enters a venturi, total flow area is reduce and pressure increases. When a rocket is out of a venturi, total flow area is increased and pressure is lower. Variation of total flow area results in pressure pulses at the restrictor assembly. Depending on the restriction of the total flow area, the pulse amplitude may be varied and controlled. The rocket holder 12 (
Base plate 14 is located into the pin connection 24 within bottom sub 3 (
In
An alternative embodiment can comprise bottom sub 35 as shown in
Sub 35 (
Indexing Pins 41 are initially placed in a position half way in profile 40 in relation to the shear pin 43 (
In the embodiment described above, the indexing mechanism will have two reset positions, one disengagement position and one engagement position. In reset positions there is no pulsation as there is no fluid passing through the embodiment. In the disengagement position, there will be no pulsation as the rocket 29 and venturi 30 will have no engagement as shown in
Claims
1. A downhole pressure pulsing apparatus, comprising:
- an upper sub that comprises a tube having a hollow interior through which fluid can flow;
- a middle sub that comprises a tube having a hollow interior through which fluid can flow;
- a lower sub that comprises a tube having a hollow interior through which fluid can flow;
- wherein said upper sub is connected to said middle sub by a connection such that the hollow interior of said upper sub is in fluid communication with said middle sub's hollow interior;
- wherein said middle sub is connected to said lower sub by a connection such that the hollow interior of said middle sub is in fluid communication with said lower sub's hollow interior;
- an impeller assembly, wherein said impeller assembly comprises an impeller that is rotatably mounted inside said middle sub's hollow interior;
- a stator, wherein said stator is housed inside said upper sub's hollow interior and wherein said stator directs fluid flow into said impeller;
- a cam assembly mounted within said lower sub's hollow interior;
- a flow restrictor assembly that varies total flow area in order to generate pressure pulses, wherein said flow restrictor assembly is mounted within said lower sub's hollow interior; and wherein said cam assembly converts rotational motion created by said impeller assembly to reciprocating axial motion within said restrictor assembly.
2. A downhole pressure pulsing apparatus according to claim 1, wherein said axial impeller assembly comprises:
- an impeller housing having a hollow interior;
- an impeller rotatably mounted within said impeller housing wherein fluid flow causes impeller rotation;
- a lower threaded connection to connect said impeller assembly to said cam assembly.
3. A downhole pressure pulsing apparatus according to claim 2, wherein said axial impeller's rotational speed is directly proportional to the rate of fluid flow directed by said stator into said impeller.
4. A downhole pressure pulsing apparatus according to claim 1, wherein said cam assembly comprises:
- a cam housing having a hollow interior;
- a barrel cam having at least one cam profile, wherein said barrel cam is mounted inside said cam housing's hollow interior;
- at least one cam follower;
- at least one barrel cam retainer is mounted within said lower sub's hollow interior;
- top inner diameter threads to connect said impeller assembly to said cam housing;
- lower inner diameter thread to connect the rocket holder.
5. A downhole pressure pulsing apparatus according to claim 4, wherein said at least one cam follower engages said at least one cam profile to convert said impeller's rotational motion to said barrel cam's axial reciprocation;
- and wherein said barrel cam retainer restrains said barrel cam from rotational motion.
6. A downhole pressure pulsing apparatus according to claim 1, wherein said flow restrictor assembly comprises:
- a rocket holder;
- a rocket; and
- a venturi;
- wherein said rocket is constrained by said rocket holder to the desired range of axial motion; and
- wherein said rocket can reciprocate axially into and out of said venturi.
7. A downhole pressure pulsing apparatus according to claim 1, wherein said impeller rotates said cam assembly; and wherein said cam assembly engages said flow restrictor assembly to generate axial motion within said flow restrictor assembly to vary total flow area.
8. A downhole pressure pulsing apparatus according to claim 1, further comprising a pressure actuated device that reacts to pressure pulses generated by said flow restrictor assembly in order to oscillate axially.
9. A downhole pressure pulsing apparatus according to claim 7, further comprising a housing for location in a drill string, said housing defining a through bore to permit fluid passage through said pressure pulsing apparatus and a shock tool mounted on said drill string;
- wherein said pressure pulsing apparatus generates axial reciprocation in said drill string in a well bore:
- wherein said drill string comprises a drill bit, drilling motor, or rotary drilling system, a measurement while drilling tool, and drill pipe; and
- wherein said flow restrictor assembly generates pressure pulses within said drill string and said shock tool converts pressure pulses into axial oscillation.
10. A downhole pressure pulsing apparatus according to claim 6, further comprising a hydromechanical indexing apparatus that switches pulsation on and off as fluid flow starts and stops by moving said venturi axially move away from said rocket;
- wherein said hydro-mechanical indexing apparatus is mounted within said lower sub's hollow interior and comprises a base plate, a housing for a base plate, an indexing barrel having a top and a bottom and an indexing profile, at least one indexing pin that engages said indexing profile, a wash pipe, a shear pin mechanism having a bottom, and a spring;
- wherein said indexing barrel is attached to said venturi and said indexing barrel and said venturi can move axially within said lower sub's hollow interior;
- wherein said indexing profile comprises an engagement position and a disengagement position;
- wherein said base plate is connected to the top of said indexing barrel;
- wherein said spring pushes said indexing barrel upward and fluid flow pushes said indexing barrel downward when fluid flow is sufficient to overcome said spring;
- wherein said indexing barrel's upward and downward movement causes said indexing pin to move within said indexing profile between said indexing profile's engagement position and said indexing profile's disengagement position;
- wherein said shear pin mechanism is connected to said indexing barrel's bottom;
- wherein a shear pin is inserted into said indexing barrel and said shear pin mechanism;
- wherein said wash pipe is connected to said shear pin mechanism's bottom and is positioned inside said lower sub's hollow interior to form an annulus between said wash pipe's outer diameter and said lower sub's inner diameter; and
- wherein said spring is located in said annulus between said wash pipe's outer diameter and said lower sub's inner diameter.
11. A downhole pressure pulsing apparatus according to claim 10, in a drilling operation, where the axial oscillation of a drill string using said downhole pressure pulsing apparatus, facilitates the weight transfer to a bit due to lower friction between said drill string and a formation.
12. A downhole pressure pulsing apparatus according to claim 10, where said downhole pressure pulsing apparatus can be used to reduce the possibility of a drill string getting stuck in a well bore or freeing a stuck object in a well bore.
13. A downhole pressure pulsing apparatus according to claim 10, where said apparatus facilitates running tubular into a well bore.
Type: Application
Filed: Aug 15, 2014
Publication Date: Jul 7, 2016
Applicant: COT Acquisition, LLC (Houston, TX)
Inventors: Aref Alali (Humble, TX), Trevor Kettles (Humble, TX), Colin Donoghue (Humble, TX)
Application Number: 14/911,326