Spiralling tapered slip-on drill string stabilizer

A stabilizer for use in a drilling string comprising:

• a substantially cylindrical body member having a central passageway to accommodate the drill string, said member defined by an upper inside surface and a lower inside surface;
• the upper inside surface of the body member defining a left-hand spiralling thread with a tapered trailing edge which spirals from the top of the upper inside surface towards the center of said body member, said left-hand spiralling thread terminating internally of said body member in an arcuate recess extending around the interior of said body member;
• the lower inside surface of the body member defining a right-hand spiralling thread with a tapered trailing edge which spirals from the bottom of the lower inside surface towards the center of said body member, said right-hand spiralling thread terminating internally of said body member in the arcuate recess extending around the interior of said body member;
• the arcuate recess in the center portion of the cylindrical body separating the terminus of the left-hand spiralling thread from the terminus of the right-hand spiralling thread;
• a key member secured to the inner wall surface of said recess of said body member, said key member having a lug extending downward and a lug extending upward, said lugs extending longitudinally within said body member within said recess and with the lower lug interrupting the right-hand spiralling thread and the upper lug interrupting the left-hand spiralling thread at the terminus of each thread;
• an upper slip member adapted to spirally thread within the upper end of said body member between said body member and said drill string, the slip defines a left-hand spiralling thread, configured to make up with said left-hand spiralling thread on said body member, the lower end of said slip terminating in a longitudinally disposed shoulder capable of abutting said upper lug upon threading of said slip within said body member;
• a lower slip member adapted to spirally thread within the lower end of said body member between said body member and said drill string, the slip defines a right-hand spiralling thread, configured to make up with said right-hand spiralling thread on said body member, the upper end of said slip terminating in a longitudinally disposed shoulder capable of abutting said lower lug upon threading of said slip within said body member.

A stabilizer for use in a drill string comprising:

• a substantially cylindrical body member having a central passageway to accommodate the drill string, said member defined by an upper inside surface and a lower inside surface;
• the upper inside surface of the body member defining a left-hand spiralling thread which spirals from the top of the upper inside surface towards the center of said body member, said left-hand spiralling thread terminating internally of said body member in an arcuate recess extending around the interior of the said body member;
• the lower inside surface of the body member defining a right-hand spiralling thread which spirals from the bottom of the lower inside surface towards the center of said body member, said right-hand spiralling thread terminating internally of said body member in the arcuate recess extending around the interior of said body member;
• the arcuate recess in the center portion of the cylindrical body separating the terminus of the left-hand spiralling thread from the terminus of the right-hand spiralling thread;
• a key member secured to the inner wall surface of said recess of said body member, said key member having a lug extending downward and a lug extending upward, said lugs extending longitudinally within said body member within said arcuate recess with the lower lug interrupting the right-hand spiralling thread of the cylindrical body and the upper lug interrupting the left-hand spiralling thread of the cylindrical body at the terminus of each thread;
• a coil-type slip member comprising an upper slip member with a corresponding left-hand coil rigidly attached to a lower slip member with its corresponding right-hand coil, said upper portion of said slip member configured to make up with said left-hand spiralling thread on said body member and said lower portion of said slip member configured to make up with said right-hand spiralling thread on said body member.

A method of attaching a downhole slip-on drill string stabilizer on a drill string rotating in a clockwise direction comprising:

• (a) providing a substantially tubular body member having a central passageway;
• (b) providing an upper inside surface with a left-hand spiralling thread with a tapered edge on the upper end of the tubular body;
• (c) providing a lower inside surface with a right-hand spiralling thread with a tapered edge on the lower end of the tubular body;
• (d) providing an upper slip member, with a left-hand spiralling thread adapted to fit within the upper inside surface of the body;
• (e) providing a lower slip member, with a right-hand spiralling thread, adapted to fit within the lower inside surface of the body;
• (f) providing a right-hand spiralling thread on the lower inside surface of the tubular body mating with the right-hand spiralling thread of the lower slip member tending to tighten the slip onto the drill string as the drill string is pulled upward;
• (g) providing a left-hand spiralling thread on the upper inside surface of the tubular body mating with the left-hand spiralling thread of the upper slip member tending to tighten the slip onto the drill string as the drill string is pushed downward;
• (h) placing said slip members in said tubular body and positioning them on the drill string;
• (i) rotating the drill string relative to the tubular body in a counter-clockwise direction in a manner tending to releasably open the slip members to install said tubular body onto the drill string to its desired position on the drill string;
• (j) rotating the drill string relative to the tubular body in a clockwise direction in a manner causing the slip members to tighten onto the drill string by rotating the slip members clockwise with the drill string relative to a stationary tubular body, causing said slip member to ride up on the tapered section of the body threads thereby wedging said slip members between body and drill string in a manner to lock the stabilizer onto the drill string at the desired position.