The invention relates to variation of concentrations of abrasive particles in a stream of drilling fluid mixed with abrasive particles, passed as an abrasive jet through abrasive nozzle(s) of a drill bit along rotations thereof, to vary the erosive power of the stream along angular sections of the borehole for directional drilling. During subsequent time periods majorities of abrasive particles are alternately deflected into two parallel channels with a different flow resistance. A resulting velocity difference between said majorities makes that the subsequently deflected majorities recombine downstream of the channels, so that high concentration stream portions of the combined majorities are formed which alternate low concentration stream portions. Synchronising the frequency of the stream portions with the rotational velocity of the drill bit results in a consistently higher erosive power of the abrasive jet within a selected angular section of the borehole than outside thereof.

The invention relates to variation of concentrations of abrasive particles in a stream of drilling fluid mixed with abrasive particles, passed as an abrasive jet through abrasive nozzle(s) of a drill bit along rotations thereof, to vary the erosive power of the stream along angular sections of the borehole for directional drilling. During subsequent time periods majorities of abrasive particles are alternately deflected into two parallel channels with a different flow resistance. A resulting velocity difference between said majorities makes that the subsequently deflected majorities recombine downstream of the channels, so that high concentration stream portions of the combined majorities are formed which alternate low concentration stream portions. Synchronising the frequency of the stream portions with the rotational velocity of the drill bit results in a consistently higher erosive power of the abrasive jet within a selected angular section of the borehole than outside thereof.

Provided is a multilateral junction (MLT), a well system, and a method for forming a well system. The MLT, in one aspect, includes a y-block having a housing with a single first bore and second and third bores extending therein, the second and third bores defining second and third centerlines. The MLT, in this aspect, further includes a mainbore leg having a first mainbore leg end coupled to the second bore and a second opposing mainbore leg end, and a lateral bore leg having a first lateral bore leg end coupled to the third bore and a second opposing lateral bore leg end. In this aspect, the mainbore leg and the lateral bore leg are twisted with respect to the second and third bore such that a first plane taken through centerlines of the second opposing mainbore leg end and the second opposing lateral bore leg end is angled.

Provided is a multilateral junction (MLT), a well system, and a method for forming a well system. The MLT, in one aspect, includes a y-block having a housing with a single first bore and second and third bores extending therein, the second and third bores defining second and third centerlines. The MLT, in this aspect, further includes a mainbore leg having a first mainbore leg end coupled to the second bore and a second opposing mainbore leg end, and a lateral bore leg having a first lateral bore leg end coupled to the third bore and a second opposing lateral bore leg end. In this aspect, the mainbore leg and the lateral bore leg are twisted with respect to the second and third bore such that a first plane taken through centerlines of the second opposing mainbore leg end and the second opposing lateral bore leg end is angled.

Geologic material in a borehole is weakened by accelerating a projectile into contact with the material. A drill bit is then used to bore through the weakened material. To accelerate the projectile, an endcap is placed in a conduit using a source of gas. The endcap isolates the conduit from the external environment. A projectile is then positioned in the conduit above the endcap. Movable members within the conduit are operated in sequence to enable single endcaps and projectiles to be moved into the conduit. Gas from the conduit is evacuated into an annulus between the conduit and a surrounding conduit, and a propellant material is provided into the conduit. The propellant material applies a force to the projectile to accelerate the projectile into contact with the geologic material. A fluid is circulated down a second annulus outside of the surrounding conduit to contact the drill bit and remove debris.

Geologic material in a borehole is weakened by accelerating a projectile into contact with the material. A drill bit is then used to bore through the weakened material. To accelerate the projectile, an endcap is placed in a conduit using a source of gas. The endcap isolates the conduit from the external environment. A projectile is then positioned in the conduit above the endcap. Movable members within the conduit are operated in sequence to enable single endcaps and projectiles to be moved into the conduit. Gas from the conduit is evacuated into an annulus between the conduit and a surrounding conduit, and a propellant material is provided into the conduit. The propellant material applies a force to the projectile to accelerate the projectile into contact with the geologic material. A fluid is circulated down a second annulus outside of the surrounding conduit to contact the drill bit and remove debris.

A reamer includes a housing, a flow tube extending along a longitudinal axis of the housing, and a plurality of reamer blocks arranged radially around the flow tube and configured to extend and retract relative to the housing. The reamer has a reamer ratio between 1.8 and 2.5. The reamer ratio is a ratio between an expanded diameter of the reamer when the plurality of reamer blocks is extended and a retracted diameter of the reamer when the plurality of reamer blocks is retracted.

A reamer includes a housing, a flow tube extending along a longitudinal axis of the housing, and a plurality of reamer blocks arranged radially around the flow tube and configured to extend and retract relative to the housing. The reamer has a reamer ratio between 1.8 and 2.5. The reamer ratio is a ratio between an expanded diameter of the reamer when the plurality of reamer blocks is extended and a retracted diameter of the reamer when the plurality of reamer blocks is retracted.

Provided is a slotted orientation apparatus for use with a keyed running tool. The slotted orientation apparatus, in one aspect includes a tubular having a wall thickness (t), and a slot extending at least partially through the tubular, the slot having an angled portion coupled to an axial portion, wherein the slot radially extends around the tubular X degrees, wherein X is 180 degrees or less.

A technique facilitates connection of tubulars along a tubing string via a linear motion. A first tubular is provided with a first connector end having a non-circular transverse cross-section, and a second tubular is provided with a second connector end having a corresponding non-circular transverse cross-section. The non-circular cross-section and the corresponding non-circular cross-section are designed to matingly engage when the first and second tubulars are moved linearly toward each other to form a tubing string. A seal is provided to seal the first connector end with the second connector end once linearly engaged. A locking mechanism may be employed to linearly lock the first connector end with the second connector end.