Alexandria University student chapter

Presents

Introduction to

oilfield operations

By: Mohamed Ashraf M. Samir

Mudlogger Weatherford SLS-Kuwait Branch

Contents:

1) Rig Types.

2) Mud Circulation

- Importance of drilling fluids.

3) Rig Components:

- Hoisting System.

- Rotary System.

- Circulating System.

4) Drill string Assembly

A) BHA (Bottom Hole assembly) consists of:

- Drill Bits.

- Drill collars.

- Heavy weight drill pipes

- Drilling Accessories.

B) Drill Pipes

5) Field personnel.

6) Introduction to Mud Logging (SLS- Surface logging System):

- Responsibilities

- SLS Sensors

- Gas system.

Kindly watch operations videos

1) Rig Types:

The type of rig that is used depends on the environment, land or offshore, water

depth and whether the installation is temporary or a fixed production platform

Rigs are generally divided into two categories:

• Onshore

• Offshore

Onshore (land) rigs are similar, but offshore rigs are of four basic types

2) Mud Circulation:

While drilling mud is continuously being pumped

1) Down through the String to the bottom of the hole.

2) Out through the bit.

3) Up through the annulus (around the drill pipe) to the surface.

4) Out the flow line over the shale shaker.

5) Then to the mud pits.

6) From mud pits through the mud pump up to the stand pipe.

7) Then through the (Kelly hose & Swivel/Top drive hose) down back into the drill

string.

- Importance of drilling fluids:

1) Clean the bottom of the hole.

2) Cool the bit and lubricate the drill stem.

3) Transport the cuttings to the surface.

4) Support the walls of the hole;

5) Prevent entry of formation fluids into the well.

6) Prevent fluid losses by forming good filter cake.

7) Transport the bottom hole conditions to the surface.

8) Transport the (MPT) Mud Pulses Telemetry to the surface.

3) Rig Components:

These components work together to accomplish the three main functions of all

rotary rigs:

• Hoisting System

• Rotating System

• Circulating System

Hoisting System:

These equipments are used to raise or lower the drill string.

Rotating System:

- These equipments are used to rotate the drill string.

- Kelly bushing and master bushing are used to transmit rotation from rotary table

to drill string.

Top Drive rotating system:

Circulating System:

Mud Pumps are used to circulate drilling fluid from the mud pits through the drill

string and out the bit.

4) Drill string Assembly

Drill string or drill assembly consists of BHA and drill pipes.

A) BHA (Bottom Hole Assembly) consists of:

- Drill Bits.

- Drill collars.

- Heavy weight drill pipes

- Drilling Accessories.

B) Drill pipes:

Drill Bits:

- Roller cone Bit

- Fixed cone Bit

Roller cone bit:

Roller Cone Bits, commonly called tri-cone bits, are the most common bits used

today. They are named tri-cone because the cutting structures are located on three

rolling cones attached to the bit body.

Involved Two main categories of tri-cone bits: are milled-tooth and insert bits.

1. Milled-Tooth Bits: These bits have steel teeth which have been milled on the

cones. The teeth vary in size and shape, depending on the formation they are

expected to drill. Long, slender teeth are used in soft formations and short, broad

teeth are used in harder formations.

2. Insert Bits: These bits differ from milled-tooth bits in that the cones do not have

steel teeth milled into them; instead, Tungsten carbide inserts (teeth) are pressed

into the cones. These are very much harder and last longer (and much more

expensive), when drilling hard formations, The inserts can come in a variety of

shapes, from long chisel shapes for firm formations to short round buttons for hard,

brittle formations.

Fixed Cutter Bits:

Fixed Cutter Bits have no moving parts. The bit body and cutting structures rotate

as one (i.e. there are no cones). These were the earliest type of bits, with the cutting

structure still evolving. The main categories of fixed cutter bits are: PDC

(Polycrystalline Diamond Compact) bits, diamond bits, and Core bits.

1. PDC Bits: The cutting structure of these bits is composed of man-made diamond

dust/crystals bonded to a tungsten carbide stud. These studs are then either pressed

or molded into the bit body. They are used in soft to medium-hard formations.

2. Diamond Bits: These bits use natural diamond (the hardest substance known) as

the cutting structure. They are usually slightly smaller than tri-cone bits to prevent

diamond damage while being run into the borehole. The design of diamond bits

varies greatly in the shape of the head, the size and setting of the diamonds, and the

water courses for cooling. The main advantage of diamond bits is that, they can be

run for long periods of time and they can drill almost any formation.

Drill Collar

- Heavy, thick-walled steel tubes having large outer diameter and small inner

diameter.

- Have spiral grooves.

Importance of Drill Collar:

- Provide weight to the bit for drilling

- Allow the lighter drill pipe to remain in tension.

- The spiral grooves are to minimize the surface of contact between hole and pipe

reducing the risk of getting stuck. This also helps the drilling fluid to flow up the

annulus in case of tight hole.

Heavy weight Drill Pipe (HWDP)

- This is the same as a drill pipe but with a smaller inner diameter and longer tool

joints.

Importance of HWDP:

- inserted as a section between the drill pipe section up and the lower drill collars

section to serve as a transition section between the two of them, this gives the drill

string the required elasticity.

B) Drill Pipe:

- Has tool joints (box and pin) which are separate parts that are welded onto the

outside of the pipe; Tool joints are of thicker outer diameter to withstand the torque

applied by tongs to tighten the connection.

- A single drill pipe is called a joint or joint of pipe.

Importance of DP:

- The drill pipe furnishes the necessary length for the drill string and serves as a

conduit for the drilling fluid.

Heavy Weight

drill pipe (HWDP)

Drill Pipe (DP)

Drilling Accessories:

Stabilizers:

- These are run between the drill collars and are of a blade type construction.

Drilling fluid can pass freely between the blades while the outer edge of the blades

contacts the wall of the hole and holds the drill collars firmly centered in the hole. -

- They do exactly as their name implies, they provide stability to the bit and

collars. This is important as it improves bit life, in addition to keeping the direction

of the hole under control.

Reamers:

These usually have the same diameter as the bit and are run a little distance above

it. As the bit wears out it tends to decrease in diameter and consequently start

drilling a smaller hole. The reamers’ function is to cut the hole out to full size

behind the bit.

Jars:

Jars are fitted into the drill string and are used in the event of the drill string

becoming stuck. They provide upward or downward jarring blows that help freeing

the string.

Subs:

A sub refers to any short Length of pipe, collar or casing that is made to perform a

specific job. The most common types of subs you can find on rigsite are the

following:

a. Crossover Sub:

A crossover sub is designed with different threaded ends for changes between

different sizes and types of drill pipe or collars.

b. Bit Sub:

This sub is used to save the thread of the bit from excessive break out such as to

change nozzles or BHA, so the break out of the bit is usually done at the

connection between the sub and the upper collar pipe. The sub is ended with a box

on both ends so that pipe and collars are always run pin down.

c. Shock Sub:

This is run behind the bit with a steel spring or rubber packing to absorb the impact

of the bit bouncing on hard formations and prevent damaging the rest of the drill

string.

5) Field personnel:

Companies in rigsite:

1. Operating company:

The operating company is the oil or gas company which has a license to drill for

and produce petroleum within a specified area. The actual license may be held by a

number of companies who are working as a partnership. in such a case one of the

partners is usually nominated as “ the operator”.

2. Drilling contractor:

To do the actual drilling of the well the operator will employ a drilling contractor.

Usually, the contractor is the owner of the drilling rig and is responsible for

providing the personnel who make up the drilling crew.

3. Drilling service companies:

As you will shortly see, there are many special drilling services required during the

drilling of the well. It is the responsibility of the operator to engage these

companies and coordinate their activities.

Company man: (Operation Company representative)

Operations supervisor, responsible of ensuring the well is drilled safely.

The performance of drilling supervisor is essentially judged on how quick the well

is drilled – as time is definitely equated to money in oil industry.

Wellsite geologist: (Operation Company representative)

Supervise and report on the performance of the geological service contractors (e.g.

Mud logging and Coring)

Responsible of sample description and formation tops determination.

Mud logging Service personnel:

Pressure engineer:

Responsible for formation’s pore pressure estimation.

Data Engineer:

Responsible for:

- ensuring that all incoming data are of good quality and are recorded correctly

- monitoring all of the drilling parameters.

- Providing a number of reports and logs.

- Maintenance and calibration of the unit equipment.

- House keeping of mud logging unit.

Mud logger:

Responsible for:

- Sample collection and processing all samples as mentioned in the drilling

program.

- Maintenance and calibration of the unit equipment.

- House keeping of mud logging unit.

Directional driller:

Responsible for:

Deviating a wellbore along a planned path to a target located a given lateral

distance and direction from vertical. This includes drilling as vertically as possible

from a given TVD.

MWD Engineer: (Measuring While Drilling Engineer):

Responsible for:

Measuring directional Survey information, hole deviation and direction (Measured

depth, Inclination, Azimuth)

(More important for drilling team- especially directional surveying, Kick off, and

stearing in horizontal well)

LWD Engineer: (Logging While Drilling Engineer):

Responsible for:

Calibration and logging physical rock characteristics (such as Gamma Ray and

Resistivity) during drilling.

(More important and useful for Geology team especially for casing and coring

point selection).

Wireline Logging Engineer:

Responsible for:

Calibration and logging physical rock characteristics after drilling hole section.

Core engineer:

Responsible for:

Providing core bits and barrels.

Insuring that equipment is made up into the BHA properly.

Monitoring and supervising all coring operations (drilling, L/D core samples, cut

core)

Cement Engineer:

Responsible for

Supervising the whole Cement Job

(Pressure testing cement line, supervise R/U and installing cement equipment,

mixing Cement and pumping Cement)

Mud Engineer:

Responsible for:

Supervising Mixing mud as per well program.

Keeping the mud parameters within the desire specifications.

(The performance of the mud can have great bearing on the quality of hole

cleaning and hole condition)

Rig Contractor Crew:

Tool pusher/ Rig Manager:

-The rig contractor manager is in charge of the drilling crew.

-When there is a requirement to get something done (for example to clear a space)

then it is the best option to ask about tool pusher.

Driller:

- Controls the activity on the rig floor and under instructions from the drilling

supervisor and the tool pusher.

- Perform the drilling operation (the driller will control the force applied to the bit,

rotary speed, and the amount of drilling fluid circulated).

- In charge of handling the pipe on connections and trips.

- Along with the mud loggers, the driller will monitor the drilling parameters such

as: pits, torque, standpipe pressure, gases…etc.

Assistant driller:

- Second in charge, stands in for driller for meal breaks…etc.

- Along with derrick man responsible for measuring BHA’s.

- Help in looking after operation and maintenance of pump.

Derrick man:

During drilling: monitor mud pits, help make up (mixing) and transfer mud, and

periodically check mud density, viscosity and volume.

During Trips: Work up on monkey board; manually pulling in or pushing out

stands.

Shaker hand:

- In charge of maintenance and smooth running of the shale shaker.

Floor hands:

- Do all the manual work on rig floor and help with maintenance of equipment.

roughneck

- Their work includes handling the tongs, cleaning, general repair and

maintenance, and pretty much anything that has to be done to keep the rig

operating.

Roustabout:

- Their work includes: cleaning, general repair and maintenance, and pretty much

anything that has to be done to keep the rig operating

Radio operator:

- In charge of communications to and from the rig.

- Organize passenger arrangement for crew change helicopters and also handles

data and equipment sent off on the helicopter.

Store man:

- In charge of monitoring the movement of all equipment and supplies to and from

the rig.

- Storage of these supplies on the rig.

6) Introduction to Mud Logging (SLS- Surface logging System):

- Mud Logging provides subsurface geological information while drilling a well.

- Mud Logging is the examination and analysis of geological information

contained in formation cuttings and drilling mud to determine if oil and gas are

encountered during drilling a well.

- Mud Logging also is used to provide critical safety functions such as determining

pore pressure, kick control and ambient gas monitoring.

- The service requires two to six people at the well site, a mobile laboratory unit,

acting as the information center for the well and may include electronic monitoring

of drilling parameters and third party service provider data.

Responsibilities:

- Monitoring, Processing and logging information from drilling operations

(including drilling data, gas and samples).

Collecting, processing, logging and analyzing geological samples (providing full

description).

- Using Fluoroscope to evaluate detailed and complex data for signs of oil or gas

(oil Shows).

- Monitoring all rig Processes (Drilling, Tripping, Cementing, Fishing).

- Interpreting information and feeding it back to the drilling team to enhance safety

and success.

- Undertaking some on-site Sensors electrical maintenance.

- Formation pore pressure estimation.

- Digital sensors that register either an ‘on or off’ state.

- Analog sensors that provide a 4 to 20mA output, 4mA represents zero output

from the sensor, whereas 20mA signifies a full scale output.

Digital sensors:

1) Draw works Depth Sensor (DDS)/ Depth wheel Sensor:

- The draw work sensor monitors the movement of the traveling block (mounted on

the draw work drum).

- Operation: rotary movement of the drum is translated into a series of pulses that

represent distance traveled, and a direction bit to determine block direction.

2) SPM (strokes per min)/pump Sensor

Proximity sensor to measure Pump Strokes and RPM

Activated by metallic target; required distance <15mm

3) RPM (Revolution per min) / Rotary speed sensor:

Proximity sensor, same idea as SPM sensor.

Analogue sensors:

1) Ultrasonic Pit Level:

Operation: Distance travelled by ultrasonic wave to mud level is

translated to current in m Amp (4 – 20)

The level in these mud tanks is measured by a Pit Level Sensor that

provides extremely important data for the operation of the drilling rig.

The total volume of fluid is continuously monitored to identify any

net gain or loss of fluid. Any increase in net fluid indicates that some

other substance, such as oil, water, or gas, is entering the process. A

decrease in net fluid means that fluid is being lost in the formation.

Calibration

4mA the tank is empty.

20mA the tank is full.

2) Mud Density (in and out):

Theory: The sensor works by recording the differential pressure

between 2 diaphragms that are positioned a known vertical distance

apart. This can then be converted to a density.

Calibration

4mA - 500 kg/m3 (4.16 ppg)

20mA - 2500 kg/m3 (20.82 ppg)

Note:

- Mud Density in: suspended in suction tank

- Mud Density out: Suspended in bosym-belly.

3) Mud Temperature (in and out):

Make sure that the sensor is kept clean, and ensure that the

temperature out sensor does not become buried in cuttings.

Note:

- Mud Temperature in: suspended in suction tank

- Mud Temperature out: Suspended in bosym-belly.

4) (Standpipe) or Annular (Casing) Pressure 0 to 5000psi or 10,000psi ranges are available.

This sensor measures the mud pressure by a direct contact with a

pressure transducer.

5) Hook load Sensor:

Two types of sesnsors may be imployed:

- Tension Hook load Sensor (HKLD)

- Hydraulic HKLD Sensor

Tension HKLD Sensor:

Installed on drilling deadline.

Operation:

When the transducer is correctly installed and clamped to the

deadline, the wire rope is bent or deflected over the central yoke.

When load is applied to the line, it will tend to straighten at the

deflection point, thus exerting an outward force on the yoke. This

force is transmitted through the clamping mechanism, creating

reaction forces on the body of the transducer. Strain gauges detect these stresses on the body of the transducer, producing a 4 –

20mA signal, which is proportional to the tension on the drill line. Calibration:

Calibration is performed through 2 points (High point and low point)

Hydraulic Hookload – Pressure Transducer and Load Cell:

Installed on Rig’s deadline anchor hydraulic system.

Operation: Same as standpipe pressure sensor.

6) Electric Torque:

Operation:

The clamp should be placed around the main power cable driving the

rotary table. It is measuring the magnetic field induced, from which

the current is automatically determined. It should therefore be

7)Flow out/flow paddle/ Return flow sensor:

Operation:

The paddle should be placed in the flow line and its length adjusted in

order to accommodate the depth of the flow line. While the paddle is

in its ‘undeflected’ position, the paddle should just barely be touching

the bottom of the flow line (this ensures that minimal flow can be

registered).

Maintenance:

Keep a regular check on the paddle for cuttings build up in the flow

line - this may ‘bury’ the paddle preventing movement.

Gas monitoring equipment

The gas trap consists of a steel box or cylinder that sits in the mud

possum belly (as near to the flow line exit as possible, but before the

shakers) and allows the drilling fluid to continuously pass through it

by means of a hole in its base.

An agitator motor sits on top of the gas trap and has a propeller shaft

(Axe) extending into the mud. The propeller continually agitates the

drilling fluid as it passes through the trap.

A continuous flow of air enters through a vent in the top of the trap

and is whipped through the mud where the maximum mud surface is

exposed. It is this air-gas mixture that is subsequently drawn into the

logging unit.

Flowing Mud

Total Gas detector:

A gas detector measures the total gas content in the drawn sample.

Gas Chromatography:

A chromatograph separates and analyzes hydrocarbons in the gas

sample to determine how much of each hydrocarbon is contained in

the sample.