Schlumberger - Drilling and Measurement Segment

Schlumberger - Drilling and Measurement Segment - Internship Presentation

I learnt about all the Drilling and Measurement equipment and procedures. During the internship period, I had to survey few technical modules which were specific to Drilling and Measurment segment, which included
• an introduction to Drilling & Measurment segment and its core services
• interpretation of Direction & Inclination terminologies
• learning of Telemetry procedures and working of Measurement While Drilling tools
• understanding of Surface System structure.

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Today the oil industry seeks petroleum that was formed and trapped millions of years ago!!!
Schlumberger looks to provide tangible and non-tangible technical expertise to its clients for oil extraction.

Here is the outline of my presentation. You may like to have a glance over it for few seconds. I will make my way through Introduction towards the conclusion in next 15 mins.

Of course, power system, source of power to run hoisting, circulating and rotating equipment
Now I will be showing you a video focusing on hoisting system with the intent to demonstrate that how is the drill string being
supported.

Video:
Draw work is an assembly with a spool or a drum for regulating the weight of drilling line
You can see the 2 inched drilling line coming out of the supply reel to tie deadline anchor to crown block (deadline) over the sheaves and reeved several times with travelling block (heavier load cx threads) finally to the draw works (fast line)
A main brake provides the driller a way of slowing or stopping the drum

Rotary table system with kelly:
The turn table in the rotary table rotates the master bushing the master bushing rotates the Kelly drive bushing the Kelly drive bushing rotates the kelly the kelly rotates the attached pipe and bit and the swivel suspends the pipe allows it to rotate and has a passage for drilling mud to enter the Kelly pipe via rotary hose (goose neck).

Down hole surveys which produce the two measurements direction and inclination of the BHA are used to ensure that the trajectory defined by the well planner is being followed so the wellbore lands on the target with correct angle and direction as desired by the clients.

How do we take it?
The workers drills the string up and down to free any trapped torque.
Turn off pump so flow reduces below MWD tool’s lower threshold.
While survey string must be stationary so driller locks it.
To trigger, driller increase the flow rate.
Field engineer detects MWD signal with encoded survey data.
Surface computer demodulates it. And he/she then examines if the survey data in within tolerances.
Additional steps: surface system software calculate new tool face, drilling proceeds if field
Engineer accepts the survey, if it fails…..retake the survey, cr updates the map.

Here are few terminologies that are essential to dwell into the concept of Direction and Inclination …

Location: the coordinates of surface location represent the geographical position where ther well started.
Kickoff point: a point at a given vertical depth where the well is to be deviated away from vertical.
Wellbore profile: planned trajectory of the wellbore: to minimize the dogleg severity and BHA torque and drag*.
Target area/point/size: defined area at a prescribed vertical depth and location. Target size is the size or acceptable liomits of the target area. A properly defined target is essential. Identifying the limits of the target.
Horizontal displacement: distance between the surface location and the current survey

Vertical section: is the length of projection of horizontal displacement onto the vertical plane of projection. A vertical plane of projection of defined by its direction by its direction (azimuth) and scaled with vertical.
Expected inclination: the expected inclination is the angle b/w the wellbore and the vertical at the survey point.
Azimuth:
TVD:
Errors in measurements derived from magnetometers
There are two types of interference:
Internal or Drill string (Earth’s Magnetic Field, Steel Components of BHA)
External (Casing Collars, Fish in hole, Formation Characteristics, Magnetic Hot Spot)
BHA: base hole assembly: The lower portion of the drillstring: the bit, bit sub, a mud motor (in certain cases), stabilizers, drill collar, heavy-weight drillpipe, ("jars") Oftentimes the assembly includes a mud motor, directional drilling and measuring equipment, measurements-while-drilling tools, logging-while-drilling tools and other specialized devices.

down hole motor is used to rotate the bit without rotating the entire string of pipe in order to drill a slant i.e. directional hole. Such method is called sliding.

Basic idea is to use downhole motor with zero bent sub along with system to rotate the drill string. It increases the rate of penetration.
Wellbore trajectory is achieved by steering the motor in the specified direction called the toolface angle.
MWD tool continuously updates the orientation of bent housing or bent sub relative to magnetic north or to gravity.
GTF, describes the orientation of the mud motor scribe line relative to the high side of well bore.
Scribe line is the reference line on the motor.
Offset between scribe line and the read out port.
MTF,describes the orientation of the mud motor scribe line relative to north.

Measurements are made downhole using sensor and MWD tools and transmitted to surface as presure pulses in mud systems.
How to Generate Continuous Waves?
The modulator consists of a rotor and stator with lobes. As the rotor turns, it opens and partially closes the space between the lobes of the stator. When the space is blocked, mud pressure increases.

Signal generation: to send data up hole, the MWD tool generates a signal by creating pressure pulses in the mud.
The tool encodes the binary data within the signal.

Signal propagation: from MWD tool back up the mud coloumn inside the drill pipe.

Inputs:
Surface, MWD, LWD measurements information
System software
MWD and LWD tool programming
Initialization data
Rig electrical power and compressed air.

Outputs:
Information for directional driller.
Drilling optimization.
LWD logs for clients.
End of well report.

Analog Sensors
Rotary Torque Sensor
Pump Pressure Transducer
Hook Load Sensor
Signal Pressure Transducer (focus)

Digital Sensors
Depth Encoder
Pump Stroke Counter

Used to find out no. of pump strokes per minute and pump output per stroke
It is digital sensor .
Installed on pump piston
Piston rod moves and switch makes the contact.
Used to determine torque in drill string:
It is analog sensor.
It is placed around top-drive power cable.
Measures electromagnetic field generated by current flowing through cable.

Two organic rich shales in the southren indus basis of Pakistan are the sembar and ranikot formations. No public data on gas shale exploration or developments for these formations are available at present.