Boring or penetrating the earth – Processes – Boring curved or redirected bores
Reexamination Certificate
2000-07-19
2002-05-28
Pezzuto, Robert E. (Department: 3671)
Boring or penetrating the earth
Processes
Boring curved or redirected bores
C175S073000
Reexamination Certificate
active
06394193
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention provides a downhole adjustable bent housing for use in directional drilling of wells used to recover oil and gas, and a method for directionally drilling a well to recover oil and gas.
2. Background of the Related Art
Wells are generally drilled to recover natural deposits of hydrocarbons and other desirable, naturally occurring materials trapped in geological formations in the earth's crust. A slender well is drilled into the ground and directed to the targeted geological location from a drilling rig at the surface. In conventional “rotary drilling” operations, the drilling rig rotates a drillstring comprised of tubular joints of drill pipe connected together to turn a bottom hole assembly (BHA) and a drill bit that are connected to the lower end of the drillstring. The BHA typically comprises a number of downhole tools including adjustable bent housings, drill collars and mud motors, and is generally within 30 feet of the drill bit at the end of the drillstring. During drilling operations, a drilling fluid, commonly referred to as drilling mud, is pumped down the interior of the drillpipe, through the BHA and the drill bit, and back to the surface in the annulus around the drillpipe. Mud motors are often used to rotate the drill bit without rotation of the drillstring. Pressurized mud pumped down the interior of the drillstring is used to power the mud motor that is mechanically coupled to and turns the nearby drill bit. Mud motors offer increased flexibility for directional drilling because they can be used with stabilizers or bent subs which impart an angular deviation to the BHA in order to deviate the well from its previous path and in the desired direction.
Surface adjustable bent housings are downhole tools that make up part of the BHA and are typically connected either between the mud motor and the drill bit or above the mud motor and the drill bit. Such bent housings are designed to provide an angular deviation in the BHA to directionally orient drilling action at the drill bit. A surface adjustable bent housing may be adjusted to a particular setting by tripping the drillstring and setting the bent housing to impart a desired angular deviation to the well.
A downhole adjustable bent housing offers savings in rig time and well costs because it is adjustable without being removed from the well. A downhole adjustable bent housing that is positionable, or deployable, from the surface can be used to efficiently influence the drop or build angle of the boring direction of the drill bit. The angle of attack of the drill bit and the resulting direction of the well can be guided using the downhole adjustable bent housing.
It is well known in the drilling industry how to obtain reliable three-dimensional location data for the bottom of the well being drilled. The driller compares this information with the target bottom hole location to determine needed adjustments in the path of the well, and the adjustments to the direction of drilling of the well may be made using the present invention.
Prior art surface adjustable bent housings use a complicated series of three connected housings that rotate independently to provide varying configurations from aligned to bent relative to the BHA. These tools require complex schemes for controlling rotational positions of each housing.
It is therefore an object of the present invention to provide a downhole adjustable bent housing that can be easily and repeatedly deployed or retracted by controllable changes made at the surface in hydraulic mud pressure in the drillstring.
It is a further object of the present invention to provide a downhole adjustable bent housing that can be adjusted without the use of wired or cabled control systems that complicate drilling operations, and that is reliable and simple to deploy and retract.
It is a further object of the present invention to provide a downhole adjustable bent housing that, once locked into its deployed position, allows the driller freedom to change the rate of the mud pumps without affecting the deployed condition of the tool.
It is a further object of the present invention to provide a downhole adjustable bent housing that provides the driller with reliable detection of the deployed or retracted status of the tool.
SUMMARY OF THE INVENTION
The above-described objects of the present invention, as well as other objects and advantages, are achieved by a downhole adjustable bent housing that is deployed and retracted by the driller by using the mud pumps located at the surface and used to circulate drilling mud in the well during the drilling process. The present invention does not require wires, cables or cumbersome reciprocation of the entire drillstring to deploy, lock or re-align the downhole adjustable bent housing, and the downhole adjustable bent housing is controllably deployed and realigned without a trip using hydraulic pressure provided by the mud pumps. The present invention provides the driller with readily available information regarding the status of the tool (aligned or deployed, and to what extent), utilizes existing mud pumps as its source of control, and is compatible with existing mud motors and other downhole equipment. The present invention provides reliable deployment and re-alignment of the downhole adjustable bent housing without interfering, with the mechanical transfer of transmission shaft power from a mud motor connected above the tool to a drill bit connected below the tool.
The present invention provides a surface-operated downhole adjustable bent housing with a bendable housing and a hydraulically actuated, tubular mandrel that engages and displaces an articulating member which, when actuated by the mandrel, sets or deploys the downhole adjustable bent housing, into its bent, or non-aligned configuration. The downhole adjustable bent housing comprises a mandrel housing
33
and a member housing
34
joined at a knuckle or joint to form a bendable housing. The housings and the knuckle provide a common center passage accommodating a transmission shaft providing power from the mud motor to the drill bit, and provide substantial rigidity to the bendable housing structure in its inactive and deployed configurations. Under the bending force provided by mechanical interaction of the mandrel and the articulating member, the joined sections of the housing are made to angularly deviate one relative to the other to form a slight angle in the downhole adjustable bent housing.
The mandrel is reciprocally disposed within a mandrel housing, but protrudes through an opening in the knuckle and into a passage in the articulating member pivotally secured in the member housing. When actuated, the mandrel overcomes a return spring that biases the mandrel towards its inactive position. The mandrel is hydraulically actuated to cycle through a number of predetermined positions to allow drilling with the downhole adjustable bent housing in either the deployed (bent) or inactive (aligned) configurations. For example, the mandrel can be hydraulically actuated from its inactive position (spring force exceeds the mud pressure forces on the mandrel) to an intermediate position (mandrel displaced into contact with the passage of articulating member, but no deployment of the downhole adjustable bent housing), back to the inactive position, and later to its deployed position (mandrel displaced further to enter the passage in the articulating member to deploy the bent housing).
The mandrel is actuated towards the articulating member by exposing the mandrel to at least a threshold drilling mud pressure applied through the drillstring by the mud pumps at the surface. When the drilling mud pressure overcomes the opposing return spring force, the mandrel is displaced to the extent allowed by the rotational position of the control collar as it engages a guide finger that is fixed to the housing. The mandrel is locked into its displaced position by the force of the mud pressure on the mandrel until the pressure is redu
Pezzuto Robert E.
Salazar J. L. Jennie
Shlumberger Technology Corporation
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