Mobil Oil Corporation

Thomas B Dellinger

Wilton Gravley

James H Sexton

John Kelly, Jr

Wilbur F Roper

Robert T Strong

William G Boston

Charles E Jones

Eugene A Hoppe

John E Walraven

A wellbore drill string is formed of a plurality of sections of drill pipe interconnected at tool joints with a drill bit at its lower end. A drilling fluid is circulated down the drill string and up the annulus between the wellbore and the drill string. A plurality of annulus reducers located at spaced-apart positions along the drill string impart a cyclical pumping action to the flowing drilling fluid. During drilling, the drill string is axially reciprocated and an extension capability to the drill string maintains continuous weight on the drill bit.

Method for improving cuttings transport during the rotary drilling of a

Directional drilling is carried out with a rotary drilling tool having a drill string, a drill bit, a drill motor for rotating the drill bit independently of the drill string, an extension sub having both axially contracted and axially extended positions for providing weight to the drill bit when moving from a contracted to an extended position so as to effect a drilling stroke by the drill bit into the wellbore bottom when drilling with the drill bit independently of rotation of the drill string and a relaxation device for removing any excess weight on the drill bit that would otherwise be detrimental to the direction drilling of a deviated wellbore.

Method of drilling deviated wellbores

Directional drilling is carried out with a rotary drilling tool having a drill string, a drill bit, a drill motor for rotating the drill bit independently of the drill string, an extension sub having both axially contracted and axially extended positions for providing weight to the drill bit when moving from a contracted to an extended position so as to effect a drilling stroke by the drill bit into the wellbore bottom when drilling with the drill bit independently of rotation of the drill string, and a measuring-while-drilling unit acting in conjunction with spiral-bladed stabilizers for effecting proper orientation of the drill bit prior to each drilling stroke.

A rotary well drilling system employs a drill pipe with a drill bit affixed at its lower end for the drilling of a wellbore. Drilling fluid is circulated through the drill pipe to remove drill cuttings. When raising and lowering the drill pipe in the wellbore, the drill pipe is continuously rotated along with continued drilling fluid circulation to prevent sticking of the drill pipe. The drill bit is rotated by a mud motor in the opposite direction from that of the drill pipe and at the same speed so that the drill bit remains rotationally stationary with respect to the wellbore and does not side-track as it is dragged along the lower side of the wellbore wall when being raised or lowered in an inclined wellbore.

Method for raising and lowering a drill string in a wellbore during

A rotary well drilling system employs a drill pipe with a drill bit affixed at its lower end for the drilling of a deviated wellbore. Drilling fluid is circulated through the drill pipe to remove drill cuttings. The drill bit is rotated in the opposite direction from that of the drill pipe to reduce the torque required to rotate the drill pipe as it is rotationally dragged along the lower side of the wellbore walls during the drilling of the deviated wellbore.

Method for reducing drilling torque in the drilling of a deviated

A rotary well drilling system employs a drill string with a drill bit affixed at its lower end for the drilling of a borehole. Drilling fluid is circulated through the drill string to remove drill cuttings. To break out a section of drill pipe from the drill string, the drill string is raised to a point where the drill string joint to be broken is above the drilling rig floor. Compressed gas is injected into the drill string to displace the column of drilling fluid to a level below such drill string joint. The compressed gas is vented and the drill pipe is broken out of the drill string.

Method and system for displacing drilling fluid from a drill string in a

Directional drilling is carried out with a rotary drilling tool having a drill string, a drill bit, a drill motor for rotating the drill bit independently of the drill string, and a bent sub affixed between the lower end of the drill string and the drill motor for angularly displacing the axis of rotation of the drill bit from the axis of rotation of the drill string. Both the drill string and drill bit are rotated to provide a straight path for the wellbore, while only the drill bit is rotated during the deviation of the wellbore from a straight path.

System of drilling deviated wellbores

Directional drilling of a high-angle wellbore is carried out by the drilling of a vertical first portion to a kick-off point at which a high-angle, deviated second portion is initiated. The wellbore is cased to at least below the kick-off point. A casing liner is lowered through the wellbore so that it extends coextensively with the casing. The liner is spaced from the casing by a casing hanger positioned above the kick-off point. The liner is sealed in the casing and prevented from rotating during drilling by a packer bore receptacle positioned between the lower end of the liner and the casing. During the drilling of the deviated second portion of the wellbore, the casing liner protects the casing from wear due to the rotation of the drill string as it lies on the lower side of the high-angle wellbore.

Method for drilling deviated wellbores

This specification discloses a rotary drilling technique for drilling a highy deviated wellbore into the earth's crust wherein a drill string comprised of drill collars and drill pipe is used to advance a drill bit attached to the drill pipe at the lower end of the drill string into the earth and form the wellbore. A first portion of the wellbore is formed to extend into the earth's crust and thereafter a highly deviated second portion of the wellbore is formed by drilling with the drill string arranged to have the drill collars located in the first portion of the wellbore and to apply compressive force on the drill pipe that extends therebelow and thus on the drill bit attached to the lower end thereof to apply the desired weight-on-bit for effective drilling of the second portion of the wellbore.

Extended reach drilling method

A method for reducing the sticking tendency of a rotating drill string in its drill cuttings and the surrounding wall cake by constructing the drill string elements, such as the tool joints, drill collars, wear knots, etc. with noncircular cross-sectional shapes. The noncircular shapes may be triangular, square or other higher order multi-faceted shapes, or elliptical, etc. Rotation of the drill string causes a periodic opening to form between the noncircular elements and the cuttings and wall cake which results in a movement of the mass of solids around the noncircular elements to positions away from the drill string, thereby mitigating the tendency of the drill string to differentially stick. Further, hydraulic seals are also likely to be broken by the reciprocating action of the noncircular elements.

Method and apparatus for reducing the differential pressure sticking

This specification discloses a technique of providing a wellbore that is extended along a track from the surface of the earth and penetrates and passes through a subsurface mineral-bearing formation a plurality of times. The wellbore is initially extended from the surface of the earth into the earth's crust in essentially a vertical direction and then is deviated toward the horizontal and extended to pass through the subsurface mineral-bearing formation from top to bottom at an oblique angle. The wellbore is then further deviated and extended along a track in an upwardly direction such that it again penetrates and passes through the subsurface mineral-bearing formation, this time from bottom to top. The wellbore may then again be deviated and extended along a downward track to again penetrate the formation from the top.

Drilling technique for providing multiple-pass penetration of a

A method of pushing pipe (e.g., casing) into a highly deviated borehole. The lower end of the pipe is plugged and the lower portion of the pipe string is filled with fluids (e.g., compressed gases, petroleum products, water, etc.) which have a lower density than that of the borehole fluid. This creates a buoyancy effect for the pipe in the deviated portion of the borehole which aids in keeping the pipe from contacting the lower side of the deviated hole. The pipe can be plugged or capped above the lightened section and filled with heavier fluid to aid in forcing the pipe downward into position. The plugs and caps are then removed, e.g., drilled out, when the pipe is ready for use. The fluids are thereby released into the mud slurry.

Method of placing pipe into deviated boreholes

In the drilling of a well, buckling of a drill string is prevented by determining the buoyed weight, sliding friction, and external forces applied to the segments of a drill string and comparing the resultant axial force on each segment with a buckling threshold to indicate when the resultant axial force exceeds the threshold. The azimuth and inclination of segments of the drill string are measured. The forces on the drill string are resolved into the axial and normal components applied to the next shallower segment. From these, the forces applied to each segment are determined.

Preventing buckling in drill string

A deviated borehole is drilled with a rotary drilling technique in which the drill string is vibrated at a suitable frequency and amplitude to reduce the friction of the drill string against the lower side of the borehole and to promote the free movement of the drill string therein.

Reduction of the frictional coefficient in a borehole by the use of

An arrangement for alleviating the problem of differential sticking of a drill string in rotary drilling of a highly deviated borehole by grinding and reducing the size of the cuttings generated by the drilling operation to enable the mud-return flow to better remove the cuttings from the wellbore. At least one full gage, rotating stabilizer-grinder is placed along the drill string at a selected point in the high angle section of the hole. In one embodiment, this stabilizer-grinder is constructed with an inner mandrel which is part of and rotates with the drill string and powers the first part of the grinder, and an outer mandrel which is free to rotate separately from the inner mandrel. The outer mandrel is full gage and fits against the borehole wall such that it remains stationary with respect thereto. The outer mandrel thus forms the second part of the grinder on which cuttings are broken and reduced in size. In another embodiment, a downhole turbine mud motor powers a grinder positioned just above the downhole drilling collars.

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Duncanville, TX, United States of America

Thomas B Dellinger