Weight-on-bit drill sub
AssigneeBbj Tools Inc.
InventorBRADLEY R. COTE
Life of this patent
Estimating the term…
Abstract
An apparatus and method for producing pressure signals which indicate when weight-on-bit, during the drilling of a wellbore, exceed a predetermined, upper limit. The apparatus includes a first mandrel and a second mandrel that inserts into and is axially moveable within the first mandrel. The position of the second mandrel may be dependent upon the balance of a biasing member's biasing strength and the weight-on-bit exerted on the drill bit. If weight-on-bit values overcome the biasing strength of the biasing member, the second mandrel may move uphole within the first mandrel and create a pressure signal that is detectable at surface so that the operator is made aware that weight-on-bit values exceed the upper limit.
Claims9
An apparatus for signaling when a weight-on-bit value is greater than an upper limit during the drilling of wellbores, the apparatus comprising:
- (a) a tubular body for connection within a drill string including a first mandrel and a second mandrel, and a central bore defining a longitudinal axis of the tubular body and creating a flow path permitting a flow of fluids between the two mandrels and through the tubular body, the second mandrel secured, at least partially, within an annular bore of the first mandrel so that the second mandrel is telescopically arranged with and axially moveable within the first mandrel between a telescopically extended position and a compressed position;
- (b) a biasing member that biases the first mandrel and the second mandrel into the telescopically extended position, the biasing member having a biasing strength;
- and
- (c) a first sealing part and a second sealing part;
- one sealing part being secured to the first mandrel and the other sealing part being secured to the second mandrel, both sealing parts being within the fluid flow path of the tubular body, the first sealing part and the second sealing part are positioned to come together when the biasing strength of the biasing member is overcome by the weigh-on-bit, together the sealing parts form a fluid seal in the central bore to prevent the flow of fluids through the tubular body.
A method for detecting if weight-on-bit values exceed an upper limit during the drilling of wellbores, the method comprising:
- (a) determining the upper limit of weight-on-bit values;
- (b) selecting a biasing member strength at least equal to weight-on-bit values;
- (c) providing an apparatus to produce the pressure signal including:
- (i) a tubular body for connection within a drill string including a first mandrel and a second mandrel, with a central bore defining a longitudinal axis of the body and permitting the flow of fluids between the two mandrels and through the tubular body;
- the second mandrel secured, at least partially, within an annular bore of the first mandrel so that the second mandrel is telescopically arranged with and axially moveable within the first mandrel between a telescopically extended position and a compressed position;
- (ii) a biasing member having the selected biasing member strength to bias the first mandrel and the second mandrel into the telescopically extended position;
- and
- (iii) a first sealing part and a second sealing part;
- one sealing part being secured to the first mandrel and the other sealing part being secured to the second mandrel, both sealing parts being within the fluid flow of the tubular body, the first sealing part and the second sealing part are positioned to come together when the biasing strength of the biasing member is overcome by the weight-on-bit, together the sealing parts form a fluid seal in the central bore to prevent the flow of fluids through the tubular body;
- (d) connecting the apparatus in-line with a drilling string so that the position of second mandrel in the first mandrel is dependent upon the balance of the biasing strength of the biasing member and an axial driving force on a drill bit;
- (e) applying torsional and axial forces on the drill string to drill a wellbore;
- (f) pumping of drilling fluids through the drill string;
- and
- (g) monitoring drilling fluid pressure to detect the formation of the fluid seal in the apparatus.
Dependencies are inferred from the claim text.