2. Drill Floor Activity

 

 

1. Describe the following drilling operation tasks and explain the purpose of each:

 

A: Tripping in is the process of connecting lengths of drill pipes to the drill string and running in hole.

Tripping out is the process of removing  drill pipes, breaking connections, from the drill string and running out of hole.

B: Tripping Speed:

Tripping speed is the time required to assemble or disassemble the drill string and the BHA while tripping in or tripping out. Important consideration has to be made in terms of maintaining a correct hydrostatic head in the wellbore.  If the crew trip out too fast, the hydrostatic head may become too low and allow hydrocarbon fluids from within the formation to enter the wellbore downhole.

If the crew trip in too fast, they could swab the formation, damaging it by pushing drilling fluids into the formation and possibly fracturing the wellbore.

C: Making up BHA

Making up Bottom Hole Assembly includes connecting

BHA components such as Bit, Mud motor, Stabilizers,

Drill collars and drill pipes. These components require

different tightening torques. The MWD tool is inside the NMDC.

D: Connection:

Connection is the process of adding drillpipes (single) or stands (3 drillpipes) to the drill string.

It is done by using tongs, which are operated by the roughnecks on the rig floor.

E: Circulating and Pumping pills

Circulation is the process of pumping the drilling fluid in the drill string, which then flows out of the bit and then upto the annulus from where it flows out of the return line for cleaning.

 

F: Slip and Cut drill line:

Drilling line which is one of the components of the hoisting gets weared off, after using for some duration, it has a certain life span, which is given in miles/tone. Once it reaches the end of its life the drilling line is replaced by new drilling which is already present on the spool, by slipping it and cutting off the used drill line.

G: Jarring:

When the drill string gets stuck inside the hole, the tool called jars are used to give a sudden pull or push on the string to relieve the stuck string, this process is called jarring.

 

H: Back Reaming

Back reaming is rotating the drillstring while tripping up. It is done to maintain a uniform borehole diameter

I: Side Tracking

Sidetracking is the process of drilling a deviated well from an existing wellbore.

It is carried out when the target is missed, or a geological obstruction is found, a new well is kicked off through the existing wellbore on a new course.

 

J: Time Drilling/Controlled Drilling

Time drilling is drilling with the help of time parameters instead of drilling parameters such as WOB.

In time drilling, the drilling is set at x m/hrs

 

K: Jetting

Jetting is a directional drilling technique used to deviate the wellbore in soft and friable formations.  A special jetting bit is used and normally has one very large nozzle and two blank, or very small nozzles.  The centre of the large nozzle represents the tool face and is oriented in the desired direction.  Maximum circulation rate is used while jetting, with jet velocity at least 500 ft/sec.

When the drillstring is on bottom, due to high circulation through large nozzle, the well gets deviated in opposite direction.

 

L: Orienting the Down hole Motor.

Orientation of the downhole motor is done using the toolface display.  The directional driller orientates the bit during sliding motion by getting the driller to rotate the drillstring until the desired motor orientation is achieved.  This is displayed on the toolface monitor (IRCT).

M: Orienting the toolface offset at Surface.

Orientation of the tool face offset is determining the angular offset between the motor scribe line and the MWD tool stinger high side.

This measurement is done in a clockwise direction from the MWD tool to the projected motor scribe line while looking downhole.

This value is then entered into the surface system.

 

2. Briefly explain the fundamentals aspects of other common operations carried out at the rig and their purposes.

 

Running Casing (types of casing, casing sections, liners, how casing is run, etc.)

Casing is thin-walled steel pipe ranging in length from 16 ft. to 40 ft. Casing is used to complete a section of a well. A string of casing is run into the well and cemented.

We run casing for a number of reasons:

v Protect the wellbore from collapse and fracturing

v Isolate troublesome formations, e.g. high-pressure zones, high angle deviations

v Provide a conduit for flow.

 

Cementing (primary cementing, purpose of cementing)

Primary purpose of Cementing is to avoid the wall of borehole from caving in and to keep the formation  

Primary cementing is the process of placing cement slurries in the annular space between the casing and the borehole or previous casing or both. In principle, the technique for this placement is the same regardless of the casing size, purpose, type, etc.: slurry is pumped down the string to be cemented, exits the bottom through the shoe and, with a preflush normally pumped ahead of it, displaces the mud while moving up the annulus.

Wire line Logging

An evaluation technique used to measure and record formation properties. This can be by the formation response to electric currents, sound waves, nuclear magnetic sources, etc. Logging tools are run down hole on an electrical wireline. They are then slowly pulled back to surface, taking measurements as they travel up the wellbore.  A log of the well is then made and presented to the client.

Wireline logging can only be done once the drilling ends.