Oil well drilling

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Mud Logging & Testing 2
Core Heat Sealer
Geologists use a core heat sealer to make an air-tight container for cores. The heat seal air-tight container keeps any formation fluids in the core from leaking out while it is being shipped to a core laboratory for analysis.

Analytical Balance
Loggers use an analytical balance to accurately weigh rock samples. They calculate a rock’s density & porosity from exact accurate weight.

Porosimeter
A porosimeter measures rock porosity, the amount of pore space in a rock. The more pore space a rock has, the more space available for the rock to store oil and gas.

[TOOL BOX]: Formation fluids such as oil, water & gas can flow through rock formations when the rock has empty spaces or pores and the spaces are connected (permeable). Click on the magnifying glass to get a closer look at the pore spaces. The ratio of the volume of empty space to the volume of solid rock is called porosity. The measure at the ease at which the fluid flows is called permeability.

Gas Analyzer
Loggers use a gas analyzer to examine samples of gas from the well. Gas analyzers not only indicate what kind of hydrocarbon gases the mud brings up, but also non-hydrocarbon gases, such as hydrogen sulfide and carbon dioxide.

[TOOL BOX]: Gas that has hydrogen sulfide in it is called sour gas; gas that contains little or no hydrogen sulfide is called sweet gas.

X-ray Diffractometer
An X-ray diffractometer penetrates a rock sample with x-rays. Different types of rock react differently to the x-rays, which allows well loggers to identify a rock’s structure.

Centrifuge
The centrifuge spins formation fluid samples at a high-rated speed. Loggers put the fluid samples into a test tube and then put the test tube into the centrifuge. The spinning or centrifugal motion separates the fluid into its components. The heaviest components (usu. water) collect on the bottom of the tube, the lighter components (such as oil) collect in the tube above the water.

Dry Sample Tray
A dry sample tray holds dry rock samples. Loggers put dry samples on the tray and then place the tray under the microscope where they examine the samples. Microscopic examination of dried samples tells loggers and geologists much about a formation’s characteristics.

HCL Testing
Mud loggers use hydrochloric acid or HCL to test for limestone. If the logger puts a drop of hydrochloric acid on a sample and the sample bubbles up or fizzes, then the sample contains limestone. Limestone sometimes holds hydrocarbons.

Mud Logs
This is a computer-generated mud log, and it’s most basic. The log records the rate of penetration, percent hydrocarbons found in the mud at various depths, and the percentage of rock types in samples caught at the shale shaker. The log may also record other well characteristics to help the well owner drill the well efficiently and safely.

[TOOL BOX]: What would you use to find out if cuttings contain hydrocarbons?

WELL LOGGING
Overview
In most wells, the owner orders a well log. A well log can review whether there is enough oil or gas in a formation to go to the expense of running and cementing production casing to complete the well.

Basic Logging Operation
To log a well, the well owner usually calls a well logging company. On land rigs, the logging company sends a truck-mounted logging unit to the well. Offshore, the logging unit is usually permanently installed on the rig. In either case, the logging unit lowers a logging tool on conductive wire line into the well to the depth of investigation. The unit then reels in the tool. As the tool comes up the hole it detects certain aspects of the formations it passes. It sends this information up the conductive wire line to the surface. On the surface, computers in the logging unit record the information. The computers then print out the information, print a log that the well owner can examine. Often the log gives enough information for the well owner to determine whether oil or gas exists in the formation.

Logging Unit
Here is a logging truck, it contains the computers, the wire line on a reel and the controls that make the logging operation work. Offshore, instead of a truck, the equipment is installed in a small house, a logging unit.

Logging Unit Details
The logging unit, whether truck-mounted or skid-mounted, houses conductive wire line on a reel, wire line controls which allow an operator to lower, stop and raise the wire line, and the computers that record and display the information relay from a logging tool through the conductive wire line.

Logging Tools
The well owner can choose from many types of logging tools. Plus, the owner can run some of the tools in combination. Logging companies group logging tools into four broad areas: electric, nuclear, sonic, and other.

Electric Log
Electric logging tools measure and record certain electrical properties of the formation. This is a recording, a log, made by an electric logging tool as it came up out of the well, passed the formations. The squiggles on the log called curves. Notice that the curves move to the left and to the right on the log. This is called deflection. A person familiar with these curves can look at the way they deflect and learn a lot about the formations.
A basic premise of the sample listed electric logs is that the salt water conducts electricity considerably better than oil. Thus a formation containing oil deflects the log’s curve different from a formation containing salt water.

Nuclear Log
A nuclear log, sometimes called a radioactive log, looks a lot like an electric log because it has curves that deflect left & right. Nuclear logs measure either natural or induced radiation in the formation. Natural radiation can indicate the type of rock and its density. Bombarding the formation with a low level radioactive source and a logging tool can indicate whether liquids or gases are in the formation.

Sonic Log
A sonic log records the time that it takes sound to travel through a formation. A sonic logging tool creates a sound that hits the formation rock near the tool. Sound moves faster through solid rock than through rock that has fluid filled pores. The curves record the travel times, and allow an expert to determine whether the rock is solid or fluid-filled. If fluid-filled, the fluid might be oil or gas.

Other Logs
Many other logging tools are available. A common one is a caliper log. This log shows the diameter of the hole and any irregularities in it. One thing caliper logs can do is help the cementing crew determine the volume of the hole. With hole-volume known, the crew knows how much cement they will need to properly cement the casing.

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DRILL STEM TESTING
Overview
In addition to logs, the well operator will sometimes order a drill stem test. The drill stem test, or DST, temporarily produces hydrocarbons through the rig’s drill string or stem. DSTs also measure and record formation pressure and temperature data. To determine formation permeability and the makeup of hydrocarbons, the well owner may run a drill stem test, DST tool. The crew runs this assembly on the drill string, or the drill stem as is sometimes called. The test evaluates a selected test zone. While qual. logging, DSTs help well owner decide whether to run casing and complete the well. A DST tool lets formation fluids flow to the surface or sometimes into a sample chamber inside the down hole tool. While the well flows, the well owner can determine the producing characteristics of the well. Such information allows the owner to produce the well more efficiently when completed.

DST Tool Components
Here is a drill stem test tool, made up on the bottom of the drill stem. From top, it has a reverse circulation sub, shut-in valve, hydraulic bypass, recorder, hydraulic jar, safety joint, packer, perforated pipe and an anchor shoe. The crew lowers this assembly to the depth the well owner wants to test, in this case, the bottom of the hole. You’ll see what the parts do as you go along.

[TOOL BOX]:Let’s see if you can build a DST tool from a bottom up. Here are the label parts of the DST. Using your mouse, drag each component into place in the proper order.

Lowering DST Tool
The crew lowers the DST tool into the hole on the drill pipe after the well is well-circulated and conditioned with drilling fluid. The hydraulic bypass is open, because the DST packer has limited clearance with the upper casing in open well bore. The open bypass allows drilling fluid in the hole to flow up inside the tool as the crew lowers it. Letting drilling fluid flow up inside the tool prevents it from creating pressure surges. Pressure surges could fracture the formation to be tested.

Sealing the Hole
With a DST tool on the bottom, the driller slacks off the drawworks’ brake to put weight on the tool. Weight causes the packer to expand. The packer seals off the hole beneath it. With the hole sealed by the expanded packer, the DST operator rotates the drill string. Rotation opens ports inside the DST tool. With the ports open, formation fluids flow into the tool and to the surface. During this time, crew members closely monitor annulus pressure. They monitor annulus pressure to make sure the packer maintains a good seal between the hole section being tested and the annulus above the packer.

Water Cushion
The test crew puts water into the drill pipe above the DST tool. This is a water cushion. The water cushion supports the drill pipe against mud pressure in the annulus, until the test starts. The water cushion also puts hydrostatic pressure on the formation when the DST tool ports are open. The hydrostatic pressure is however, not enough to keep the formation from flowing into the DST tool. The water cushion is just that, a cushion. It keeps the formation fluids from surging with great force into the tool and the drill string. If allowed to surge, the force could damage the recording instruments and the tool and the formation rock.

Fluid Flow
With the ports open in the DST tool, formation fluids flow. They push any drilling fluid in the hole below the packer into the tool. Then they flow up the tool and the drill string to the surface. The test crew first lets the well flow for a short time to clear out the drill stem. They then shut in the well for a time to allow pressure to build. The well owner then allows the fluid to flow for a few hours of for several days depending on the well. Produced fluids are contained in a holding tank or burned off if they reach the surface. During the flow period, the owner determines the well’s production potential and fluid properties.

Pressure Charts
After letting a well flow for the required time, the test crew closes the shut-in valve by rotating the drill string. The flow of formation fluids stops. With flows stopped, formation pressure builds up inside the tool. This pressure build up is recorded on a pressure chart in the tool. Later the well owner examines the chart on the surface. The record of the pressure build up rate gives information about the permeability and size of the formation.

[TOOL BOX]: Permeability is the quality of a formation that allows oil and gas to flow through the pore spaces of rock. Highly permeable formations allow fluids to flow easily. A formation with low permeability is called “tight” formation. It is harder to produce than a formation with high permeability.

Reverse Circulating
To remove the DST tool from a hole, the driller first opens the reverse circulation sub. The driller usually opens the reverse circulation valve hydraulically by pumping drilling fluid down the annulus. This increased pressure in the annulus opens the sub. With the sub open, drilling fluid reverse circulates down the annulus and up the tool and drill string to the surface. Reverse circulation pumps the remaining formation fluids out of the drill stem and puts drilling fluid back in. The drilling fluid kills the well, that is the drilling fluid once again keeps the formation pressure under control.

Removing DST Tool
To pull the drill string & DST tool from a hole, the driller first releases the packer by easing up on a string. If necessary, the driller uses the built-in hydraulic jar to jar on the DST tool. In most cases, jarring loosens the packer and frees the tool. If the driller can not pull the packer free for some reason, he can separate the tool at the safety joint. Removing the tool above the safety joint gets all of the tool above the packer, including the recorder with its data.

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VOLUME TEN POWER SYSTEM & INSTRUMENTATION

POWER SYSTEM
Overview
There’re three basic ways a rig distributes or transmits power: an AC to DC power system, or SCR power system, a DC to AC power system, and a mechanical power system. At the heart of every rig power system, whether electrical or mechanical, is the prime mover. A prime mover is the rig’s main source of power. Most rigs have more than one prime mover. Prime movers are almost always large and tumult combustion engines. Some equipment on the rig requires hydraulic power and pneumatic power. The rig’s hydraulic & pneumatic systems also obtain their power from one of the three basic distribution systems.

[TOOL BOX]: Just what is power and how is it measured. Well, to understand power, we have to understand force and work. Think about a force is a push or a pull. If a constant force is applied over a distance, we have work. Work = Force X Distance. Power is the amount of work done per unit of time. See these horses pulling their loads, the top one is moving much slower than the second. But by the time they’ve gone the same distance, they’ve done the same amount of work. The bottom one though, finished five times quicker than the first. So it did five times as much work per second as the top one. That means the bottom horse delivered 5 times as much power as the top one.

Prime Movers
Large diesel engines are the main power source, the prime movers, for most rigs. These engines often produce from 500 to over 8000 hp (or 350-5600 KW). Rig builders usually house several engines together to drive the rig’s equipment. They also keep extra engine sets available for back-up engines. Most rig engines are diesel, because unlike gasoline engines, they can produce a lot of power when running slow. Also diesel fuel is not as volatile as gasoline, so it is safer to use, transport and store.

[TOOL BOX]: A diesel engine takes chemical energy or fuel and converts it to mechanical energy, rotational force to power the rig equipment.

AC to DC Power System
Here is an AC to DC power system. The prime mover, usually a diesel engine, supplies power to the AC generator, also called an alternator. From the AC generator, AC current is sent to the SCR (the silicon controlled rectifier). An SCR is a high-tech solid state electric device. The SCR converts AC to DC current, which drives the heavy rig equipment, such as the mud pumps, the drawworks, and the rotary system. Auxiliary loads such as small pumps and rig lighting need lower voltage AC power, so a transformer steps down or reduces the voltage to the rig’s auxiliary electric equipment.

DC to DC Power System
Here is a DC to DC power system. The prime movers, usually diesel engines, power DC generators. From the generator, DC current goes through a control panel directly to DC motors. The DC motors power the mud pumps, the drawworks, and the rotary system. A smaller AC generator is also part of the system. It supplies AC current for equipment that works best with this current type, for example, a chemical mixing pump requires AC power.

Mechanical Power System
Here is a mechanical rig system. Mechanically powered rig’s usually smaller than those rigs which use electric power. The prime mover drives a mechanical compound transmission, which in turn, powers the drawworks, the rotary table, and the mud pumps. Auxiliary loads such as small motors are supplied with AC from an alternator connected to the prime mover.

AC to DC POWER SYSTEM
Overview
Alternating current put on by the AC generators goes through heavy-duty electric cables to a special device called silicon controlled rectifier (or SCR). The SCR converts AC to DC. Other heavy-duty electric cables carry DC electricity to the DC motors. The DC motors convert electrical energy back into mechanical energy to drive the powerful hoisting, rotating and circulating equipment.

Diesel & AC Generator
Rig owners like to use AC generators because they can be built to be very powerful for their sizes, which is an advantage over DC generators. Also rig equipment can distribute AC easier than DC. But direct current has certain advantages when driving large equipment. Mainly DC motors produce a lot of torque at low speed that the drillers can easily control. Using remote switches on this console to control the SCR control panel, the driller can select and deliver the power from the various generators wherever it is required. But some AC generators power big motors. In fact, most of today’s diesel electric rigs use AC generators and a system called an SCR power system. Here, a large AC generator, an alternator, is connected to the diesel engine prime mover. As the engine mechanically drive the AC generator, the generator produces alternating current, or AC electricity. AC is like the electricity used in most cities and homes.

[TOOL BOX]: Remember, an electric generator or alternator takes mechanical energy and creates electrical energy. An electric motor does just the opposite. It takes electrical energy and creates mechanical energy.

SCR Switch & Control Gear
Equipment in this electrical cabinet converts or rectifies (as the electric term) most of the AC current produced by the AC generators into direct current. As mentioned before, rig owners usually prefer DC current for driving the very large equipment that requires precise variable speed control and high torque. The control equipment includes solid state electrical components called silicon controlled rectifiers or SCRs. Heavy duty electrical cables come out of the cabinet and carry DC electricity to the powerful motors, driving the circulating, hoisting and rotating equipment.

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DC Motors
Usually large DC motors supply power to the mud pumps, the drawworks, and the rotary table or top drive. Sometimes the drawworks mechanically drive the rotary table, but on some rigs the rotary table has its own motor. The driller can control the speed of a DC motor very accurately, which is why rig owners use DC instead of AC motors. With accurate speed-control, the driller can accurately set the speed the drawworks slips, the mud pump operates, and the rotary table turns on rigs without a top drive.

AC Motors
Various small components on a rig need power, too. For instance, these two centrifugal pumps move mud from a tank to supercharge the intake of the mud pumps. In this case, it is more efficient to use small motors to power the centrifugal pumps rather than using the prime movers, hydraulic fluid or air. Here is another AC motor; it powers the paddles on the mud agitator in a mixing tank. AC motors generally power equipment that does not require a lot of horsepower. So they vary in power from less than 1 hp (or .75 KW) to more than 150 hp (100 KW).

[TOOL BOX]: Here is a chart covering the uses of advantages of AC & DC motors. Drag each test box to its proper place on the chart, then click on “accept”.

DC to DC POWER SYSTEMS
Overview
For electric power distribution, some rigs use DC to DC power. DC to DC was the first electric power system. In a DC to DC system, each engine drives a DC generator. The DC generator converts the rotating mechanical energy of the diesel engine into DC electricity. Heavy duty electrical cables carry DC electricity via the control panel to large 1000 hp (or 700 KW) DC motors. The motors convert the electricity back into mechanical energy. This mechanical energy powers the hoisting, rotating & circulating equipment.

DC Motors
For large equipment, most rig owners prefer DC motors over AC motors. DC motors put out high torque (twisting force) at low speed. Further, the driller can easily control the torque from his console on the rig floor. Keep in mind, though, that recent technological advances are allowing computerized controls and variable speed AC motor drives to be used where only DC motors were used in the past.

AC Generator (Alternator)
This is a generator (or alternator) on a DC to DC rig. It generates the AC electricity that DC to DC rigs need. The alternator powers smaller equipment on a DC to DC rig, like the small AC motors on centrifugal pumps, air conditioners, lights, fans, water-maker units and other small equipment.

[TOOL BIX]: Which of these two motors do you think is an AC motor? Select one and then click the “accept” button.

MECHANICAL DRIVE POWER
Overview
Mechanical drive rigs normally compound (or connect) two or more engines to drive the main pumping, rotating and hoisting equipment. Generally small to medium size land rigs use mechanical drives. They use clutches, converters, chains, shafts, belts or compounding transmissions to connect the prime movers to the driven equipment. Here is a common way to get power to the components on a mechanical drive rig. This shows three engines that the rig owner compounded. That is the power from each engine goes through a series of sprockets and chains & housing, called a compound. The compound transfers engine power to the drawworks, the rotary table, and the mud pumps.

[TOOL BOX]:
You’ve probably notice that the engines and motors are commonly rated according to the amount of power they produce in horsepower or kilowatts. Power is the amount of work performed over a period of time. In the English system of measurements, power is often measured in foot-pounds per second. One foot-pound per second is the amount of power that would lift a one-pound weight one foot off the ground in one second. Click on the weight with your mouse to lift it. One horsepower is equal to 550 foot-pounds per second. So one horsepower is the amount of power that would lift 550 foot-pounds one foot off the ground in one second. Click on the weight. In the metric system of measurements, power is often measured in joules per second. A joule is equivalent to one Newton-meter. One joule per second is the amount of power that would lift a .102 kg object one meter off the ground in one second. Click on the weight with your mouse to lift it. One horsepower is equal to 746 joules per second. So one horsepower is the amount of power that would lift a 76.1 kg object one meter off the ground in one second. Click on the weight.

Compound Drive
In a compound drive, engine power usually goes through torque converters to the sprockets & chains. Steel guards cover the sprockets & chains, removed here so you can see them. Torque converters smoothly transfer engine power to the compound. Here you can see the steel guards covering the machinery in the compound. Not only do the guards protect personnel, they also keep a lubricating oil spray confined to the chains & sprockets. Also, note that large V-belts called power bands drive the mud pumps. Steel shrouds also guard them.

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HYDRAULIC & PNEUMATIC POWER SYSTEM
Overview
Many tools use hydraulics to transmit power. Examples include the Kelly spinner, the Iron Roughneck, and casing tongs.

Hydraulic Force
Hydraulics means transmitting power by pushing on a confined liquid. Here is a piston moving inside a cylinder. Hydraulic fluid fills the cylinder to the left of the piston. The piston’s surface area is 10 in2. If a pump puts 1000 pounds per square inch (or psi) of hydraulic fluid pressure on one side of the piston, this 1000 psi acts on the 10 in2 piston to produce 10000 lbs of force. That’s a lot of force available for powering certain tools and equipment.

Hydraulic Power Pack
Here is a typical hydraulic power pack used on many rigs. It has an electrical motor or internal combustion engine to power the high pressure pump. The pump takes hydraulic fluid from the reservoir and sends it out a high strength steel-reinforced hose to the devices needing hydraulic power. The fluid returns to the reservoir after it passes through the Kelly spinner or other tool. The hydraulic power pack is a closed system; the fluid is used over and over.

Pneumatically Powered Equipment
Certain controls, valves and tools on the rig are air of pneumatically operated. For instance, the driller uses pneumatic controls on the driller’s console to engage & disengage clutches on equipment like the drawworks. The rig crew may use air-powered hand tools, like a grinder. They also use an air hoist, an air powered winch, to hoist and move relatively light equipment onto and around the rig floor. Many diesel engines on rigs have an air starter, which is air-operated motor that turns the engine crankshaft over to start it. Finally, a floating rig’s motion compensator operates large amounts of compressed air to compensate for vessel heave or keeping the drill string in position.

[TOOL BOX]: Which of the rig types uses a motion compensator? Select the correct answer or answers and then press “accept”.

Rig Air Compressor
An air compression system provides air pressure to operate the pneumatic controls, valves & tools on the rig. Rigs use rotary screw compressors or reciprocating compressors to compress air. A typical reciprocating air compressor has two, three or four pistons moving inside cylinders. The compressor takes in air from the atmosphere, and raises its pressure, that is, compresses it. The volume tanks stores a given amount or volume of compressed air that is ready for use when needed.

[TOOL BOX]: Air, compressed 100 pounds per square inch, or 670 KPa, can be dangerous. Care must be taken when working on or around air systems. Always wear proper safety equipment, such as a hard hat, eye & ear protection, work clothes and work boots. Never attempt to open a component of an air system or a section of pipe without making sure that all of the air has been bled off first. Periodically check pressure and temperature gauges to be sure they’re at the proper level. Also, inspect pipes and vessels for corrosion. And be aware, if there’s a fire on the rig, any break in the air system instantly adds oxygen from the air to fan the flames.

RIG INSTRUMENTS
Overview
A drilling rig has many instruments and gauges. They help the driller and other crew members keep track of the drilling operation. Rig instruments vary from the most basic to sophisticated computers with video displays. Here we’ll cover the basics.

Driller’s Console
The driller’s console is the driller’s work station on the rig floor. It has several instruments and gauges. All of them help drillers track the drilling process and keep them informed of the situation. Indicators and gauges on the driller’s console include the weight indicator, the pump rate indicator, mud pump pressure gauge, rotary tachometer, rotary torque gauge, tong torque gauge, mud return mud flow rate indicator, mud tank level indicator and trip tank volume indicator.

Weight Indicator
The weight indicator is the largest gauge on the driller’s panel. It indicates the hook load, and weight on the bit. The hook load is the total amount of the weight hanging from the hook. Weight on the bit (or WOB) is the amount of weight put on the bit by the drill string. It is less than the hook load. The weight indicator is extremely sensitive to hook load changes. Drillers can use the hook load changes to monitor the amount of drag or friction the well bore puts on the drill string when they move the pipe up or down. Or because it is so precise, the driller can use it to monitor the operation of down hole tools requiring small variations in weight.

Pump Rate Gauge
The pump rate gauge shows the number of times one mud pump piston moves per minute. This console has two pump rate gauges because this rig has two mud pumps. The driller can determine the total volume of mud being pumped by multiplying the pump rate by the number of pistons in the pump times the amount of mud each piston pumps.

Pump Pressure Gauge
The mud pump pressure gauge shows drillers the amount of pressure the pump is putting out. They monitor pump pressure from the standpipe to ensure that it is the correct amount needed to keep the hole clean and return cuttings back to the surface.

Rotary Tachometer
The rotary tachometer shows the revolutions per minute (or rpm) of the rotary table or a top drive unit. Drillers monitor rotary rpm because they need to know the rate the bit is turning. Different bits rotate at different rpms. Rpm ranges for a bit are specified by the manufacturer.

Rotary Torque Gauge
Drillers use the rotary torque gauge to see how much twisting force or torque the rotary is applying to the drill string. Knowing rotary torque helps keep drillers from parting the drill string because of too much rotary torque. Parting the drill string in this manner is called “twisting-off”.

Tong Torque Gauge
A tong torque gauge helps the driller and the rotary helpers make up the drill pipe and drill collars with the right amount of torque. Too little torque or tightness in the connection may leak or unscrew while drilling; too much torque can damage or gall threads, which cause them to leak and eventually to come apart.

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Mud Return Flow Rate Indicator
Drillers use the mud return flow rate gauge as a relative indicator of how much drilling fluid is returning at the flow line. The sensor is mounted in the mud return line, the flow line. A paddle inside the return line moves as mud flows past it. As the paddle moves, it sends a signal to a readout panel, mounted on the driller’s control console panel. The driller sets the readout so that as long as return flow is normal with constant pump speed and output, no alarm sound or lights up. However, when the return flow rate changes, increases or decreases, the paddle’s motion also changes. This change in paddle motion sends a signal to the driller’s readout and sounds or aluminates an alarm. A change in the return flow rate of the mud may indicate one of the two things: if the flow rate decreases, mud may be being lost to a down hole formation; if the flow rate increases, formation fluids may have entered the hole and are forcing drilling mud out. So a mud return flow rate indicator can help drillers detect kicks and loss of circulation.

Mud Tank Level Indicator
This mud tank has a special float in it. It goes up or down as the mud level in the tank rises or falls. Usually several mud tanks have floats in them. The floats send a signal to a digital totalizing panel mounted on the driller’s console. This panel takes the tank level signals from all the floats in the tanks, totals them and sends the information to the chart recorder next to the panel on the rig floor close to the driller’s console. If the level of mud in the tanks falls and no one has removed mud from the tanks, then that it is likely that mud is being lost to a down hole formation. If the level of mud in the tanks rises and no one’s added mud to the system, then it is likely that formation fluids are flowing into the well. Thus a mud tank level indicator is another tool to help the driller detect kicks and loss of circulation.

Trip Tank Volume Indicator
A trip tank volume indicator helps the driller monitor the amount of mud being displaced by the tubulars or wire rope being run in and pulled out of the hole. Crew members calculate tubular displacement before each trip using tables from a handbook. Then during a trip, they compare the calculated volumes to the actual displacement. Close monitoring of the trip tank during trips is crucial to proper well control.

[TOOL BOX]: Here is a quick little review for you. Click on the weight indicator on this control panel then click on the “accept” button.

Drilling Recorder
A drilling recorder makes a record of drilling variables such as the hook load, weight on bit, rate of penetration, torque, pump strokes and pump pressure during drilling. It’s usually located in the doghouse on the rig floor. The driller puts a chart onto the revolving drum. Several pens with ink in them trace records onto the chart. Drilling recorders may have from one to several pens depending on how they’re hooked up. The recorder gets signals from sensors mounted near the gauges that measure the drilling variables. For instance, a load cell on the dead line anchor sends its hook load and weight on bit. Here is a photo of a drill recorder. Note that it has a hinged plexiglass cover; the drillers can raise it to change the chart when necessary.

H2S Instrumentation
Hydrogen Sulfide, H2S or Sour Gas, is the most poisonous gas encountered in drilling operations. It occurs worldwide in various concentrations associated with gas, oil and water produced from wells. It is extremely toxic, explosive and heavier than air. It is also colorless so you can not see it. In low concentrations, it smells like rotten eggs, but you can not depend on your sense of smell to escape harm. H2S quickly deadens your ability to smell. Where H2S may be present, rigs are equipped with sensors, automatic monitors and alarms. This is an audible and visual H2S alarm. The horn sounds a siren or the light flashes brightly if they’re activated by H2S sensors placed on the rig. This H2S sensors place near the mud tanks; others may be at the bell nipple on the rig floor, shale shakers, flow line, rig accommodation’s air intake and other places on the rig. When a sensor picks up H2S gas above a predetermined level, the monitor triggers both the visual and audible alarms. Upon hearing or seeing the alarm, crew members can take action to avoid injury or death. You’ll receive detailed H2S training if your rig is working in an area where H2S may be encountered.