External Casing Packer
The External Casing Packer (ECP®) has an Inflatable Packing Element that is run as an integral part of the casing string to provide a mechanism to seal between casing OD and the well bore wall. ECP features a fully continuous mandrel as part of the casing or liner, and an Inflatable Packer Element as the main component. ECPs can be used to support primary cement, isolate lower zones during multi-stage cementing, and isolate lost-circulation zones during cementing. Most packers are bladders that are inflated by fluid pressure and have different pressure ratings.
Microannulus
Microannulus is a very small gap that can form between the casing or liner and the surrounding cement in primary cementing operations. Microannulus can jeopardize the hydraulic efficiency of a primary cementing operation and act as a channel for reservoir fluid migration, compromising the well's integrity. Microannulus could be created due to temperature & pressure variations during or after the cement job. These variations can cause cement shrinkage, cracking, or reverse ballooning of casing to create these micro gaps. Improper removal of mud or film of oil on the pipe before displacing with cement can also result in microannulus.
Solid Expandable Tubular
Solid Expandable Tubulars are casing or liners, which are expanded downhole after running the pipe in the well. Metallurgically, the tubular expansion process is equivalent to cold-working steel tubular to increase the diameters to the required size downhole. The process is complicated and requires overcoming operational hurdles for the expansion of pipe in a downhole environment. However, the technology provides the distinct advantage of extending the well depth where well conditions limit the number of regular-size casings that can be used to reach planned well depth.
An expansion cone is used to permanently mechanically deform the pipe. The cone is moved through the tubular by hydraulic pressure across the cone itself and/or by a direct mechanical pull or push force.
Selective Firing System
Selective Firing System is a perforating switch technology that utilizes unique switch identification logic to selectively perforate multiple intervals in a single trip. Digital communication is used to operationally check and arm the switches. The system uses series of micro-processors with unique addresses and can be checked from surface. In case of a misfire, that device can be skipped to go to the next device.
Extreme Overbalance Perforation
Extreme Overbalance Perforation is a method of perforating a well by applying a very high pressure surge to the formation. Pressure surges are designed to overcome fracture initiation pressure and break down each perforation tunnel with a very short fractures. Extreme Overbalance Perforation approach has been found to be a more effective technique than overbalance or underbalance perforations for water injection wells.
Once the perforation guns are at depth, the string is filled with small amount of liquid (brine, acid, solvent or frac fluid) at top of the gun. Rest of the string is filled with compressed gas (Nitrogen) before initiating the perforation sequence. On detonation, liquid is driven into the perforation at very high rate due to rapid expansion of gas and initiates fractures to extend effective wellbore radius.
Overbalance Perforation
Overbalance perforation is the process of perforating the well with hydrostatic pressure inside the casing or liner more than the reservoir pressure. Overbalance perforation ensures maintaining complete control on the well. However it risks causing formation damage as the wellbore fluid tends to flow into the reservoir through the perforation tunnel.
Underbalance Perforation
Underbalance perforation is the process of perforating the well with hydrostatic pressure inside the casing or liner less than the reservoir pressure. This has a distinct advantage that soon after the perforation, reservoir fluid tends to flow into the wellbore. In the opposite scenario of pressure inside casing or line being more than reservoir pressure, the wellbore fluid tends to flow into the perforation tunnel and could damage the reservoir.
Perforating underbalance without appropriate pressure control equipment has a risk of developing into a well control situation. When using Tubing Conveyed Perforation (TCP), it is possible to reduce the hydrostatic pressure inside tubing by displacing part of the tubing to lighter fluid or Nitrogen before perforation. Pressure can be safely contained and observed on surface soon after perforation.
Poor Boy Degasser
Poor boy degasser is an equipment to separate harmful gas in drilling mud and discharge harmful gas away from rig floor to a flaring area complete with an ignition source as per environmental regulations. It's a vertical vessel that is rigged up downstream of choke manifold during well control situation.
Height and diameter of an atmospheric separator are critical dimensions which affect the volume of gas and fluid the separator can efficiently handle. Baffles are installed inside the vessel which assist the fluid and gas separation process. Gas and fluid inlet should be located approximately at the midpoint of the vertical height of the vessel. This provides the top half for a gas chamber and the bottom half for gas separation and fluid retention.
Spider Elevator
Spider elevator and slips are used for casing running operation. They are used instead of regular slips when the rotary table bushing size is not compatible with the tubular being run. Spider elevators are also used for running flush joint casing pipes because flush joint casings don’t have the collar. The spider elevator grips the body of pipe while running in or pulling out of a hole.
Spider slips & elevators are powered by a heavy duty high-strength coil spring or by air. Driller or another crew member can operate the power slips remotely through a remote panel.
Texas Deck
On some large land rigs with 38 foot substructures, most offshore jack-ups and even semi-submersibles used in shallow water have a deck below the rotary table and rig floor where workers can access the BOP stack. This deck is called 'Texas Deck' or 'Texas Floor'. This deck is suspended from the cantilever by adjustable cables and is accessed from the main deck by semipermanent stairwell. Texas deck is used primarily for installing the wellhead and nippling the BOP stack up and down. Height of Texas Deck can be adjusted in most designs as they are often hung from overlying substructure with cables.
Lift Nubbin
Lift nubbins or lift caps are used for lifting drill pipe or drill collars with catline, winch or crane as the case may be. Lift nubbin has threads matching to the box end of the pipe and a lift handle or bails to be able to fasten a clamp. Once the threaded part of the nubbin is screwed into the box end of the pipe, a clamp is connected to the lift handle of the lift nubbin or cap for lifting the pipe. The clamp could be connected to a sling from catline, winch or a crane to provide required pull.
Lift nubbins or caps are manufactured from a single piece of high quality steel to ensure integrity of the lifting accessory and eliminate risk of failure. Lift caps or nubbins are made as light as possible for handling while still offering the required factor of safety for lifting the load.
Stabbing Board
A stabbing board is a temporary platform rigged up in the derrick or mast to facilitate casing running operation. It is installed some 20 to 40 ft above the rig floor where derrickman or another crew member guides the casing joint while running casing in a well. The board may be wooden or fabricated of steel girders floored with anti-skid material.
Sophisticated stabbing board designs are powered electrically to be raised or lowered to the desired level and can be folded back to avoid possibility of damage to the board when not in use. Stabbing board serves the same purpose for casing running as a monkey board to running drill pipe stands but is temporary instead of permanent.
Mooring System
Mooring system is a mechanism used for station keeping of a floating vessel or a platform in sea. The system consists of Mooring lines, anchors and connectors. Different type of mooring systems that are commonly used are catenary, taut leg, semi-taut, spread, single point and dynamic positioning. Type and configuration of mooring system to be deployed depends on water depth and environmental factors like wind, wave and current. Dynamic positioning (DP) uses computer controlled thrusters and propellers to maintain vessel's position. DP vessels can combine with other mooring systems for redundancy.
Hydrocyclone
Hydrocyclones are used on drilling rigs as solid control equipment for separation of solid particles from drilling fluid. They are commonly known as desander and desilter. Both use the same principle for separating solid particles from drilling fluid, but have size and ability to remove different size of particles.
Hydrocyclones do not have any moving part. They depend on the feed pressure, or velocity, into the cyclone to generate a centripetal force. This centripetal force allows the cyclone to separate coarse or dense particles from fine particles and liquid phase.
The equipment is formed by a cone in the lower part and in the upper part by a cylinder. Liquid slurry enters at the top of the conical wall of the hydrocyclone through a vortex finder which creates tangential flow creating a strong vortex in the hydrocyclone.
They depend on the feed pressure, or velocity to generate a centripetal force. This centripetal force allows the cyclone to separate coarse or dense particles from fine particles and liquid phase. Coarse particles move closer to the wall due to higher centrifugal force and exit from the lower end whereas fines suspended in the liquid move up through the middle part of the vortex to exit from the top.
Desilter
Desilter is a solid removal equipment that uses Hydrocyclone principle for removing smaller solids from drilling fluid. It is placed after desander in sequence of fluid flow system on the rig. Drilling fluid is injected into desilter as a tangential flow. The centrifugal forces generated due to the movement of fluid through the hydrocyclone moves the solid particles outwards. The dispersed particles move downward in a spiral path into as underflow while the cleaner and lighter density liquid mud travels up through a vortex in the center of the hydrocyclone, exiting through piping at the top of the hydrocyclone. Desilter cones are 4-6 inche diameter to remove fine sands and silt particles down to 20 micron. Hydrocyclones are made of polyurethane because of its wear resistance and less weight than steel.
Desander
Desander is a solid removal equipment that uses Hydrocyclone principle for removing larger solids from drilling fluid. It is placed after degasser in sequence of fluid flow system on the rig. Degassed mud is injected into desander as a tangential flow. The centrifugal forces generated due to the movement of fluid through the hydrocyclone moves the solid particles outwards. The dispersed particles move downward in a spiral path as underflow while the cleaner and lighter density liquid mud travels up through a vortex in the center of the hydrocyclone, exiting through piping at the top of the hydrocyclone. Desander cones are usually available 8 – 12 inch diameter to remove drilling solid particles in 50 - 80 micron range. Hydrocyclones are made of polyurethane because of its wear resistance and less weight than steel.
Centrifuge
Centrifuge is a solid control equipment used on drilling rigs for removing fine and ultrafine particles from drilling fluid. Many solid removal equipment are used on the rigs, but centrifuge removes the finer particles that the other equipment like shale shaker or hydro-cyclones are not able to remove. Removing fine solids from mud system is important to be able to maintain mud properties within required specifications for drilling a well.
Not able to remove fine solids increases percentage of low-gravity solids (LGS) in the mud system, which adversely affects rate of penetration (ROP) and bit performance resulting in more trips for drilling the same footage. The mud becomes thicker and harder to pump, causing higher equivalent circulating density (ECD). Higher percentage of LGS also requires dilution, needing additional chemicals to maintain required mud properties.
Centrifuges use conical drums which rotate at high Revolutions Per Minute (RPM) to produce high G-force. Drilling fluid enters from one end and solids are separated from liquid phase due to high G-force to exit the bowl from the other end. Advanced centrifuges use variable frequency drive to be able to operate at varying speed to match required RPM of the bowl.
Choke Valve
Choke valve is a mechanical device that is used for creating restriction in a flow line to vary the pressure or flow rate. Two types of chokes used on the rigs are fixed choke or variable choke.
A fixed choke has a fixed orifice size to allow the flow through the valve. The term ‘bean’ is used to refer to the piece of hardware installed inside the valve that has an orifice or opening drilled into it. If there is a need to change the bean for changing size of the opening or for replacement due to erosion, the valve needs to be disassembled.
An adjustable or variable choke provides the mechanism to be able to vary orifice sizes either manually or hydraulically through a remote panel. Adjustable choke makes it possible to accommodate a range of pressure and flow rate changes without the need to disassemble the valve.
Choke Manifold
Choke manifold is an arrangement of special valves called choke valves. The manifold is used for diverting the flow from the well when BOPs are closed in well control, well killing or well testing operations. The manifold consists of high pressure pipes, valves and pressure gauges to be able to safely handle pressure from the well. It has adjustable choke valves, which can be manually or hydraulically controlled from a remote panel.
In well testing and production operations, choke manifold facilitates managing speed and pressure of flow of formation fluid that enter the processing equipment through an arrangement of fixed and adjustable choke valves. This helps in controlling production and reduces the risk of equipment damage downstream of the choke manifold.
Underbalanced Drilling
Underbalanced drilling, or UBD, is the process of drilling a well by maintaining a hydrostatic head in the wellbore intentionally lower than the fluid pressure in the formation. The difference between the fluid pressure in the formation and the hydrostatic pressure in the well is called 'Underbalance'. The hydrostatic head can either be naturally under balance or by injecting natural gas, nitrogen, or air. If there is enough porosity and permeability in the rock, the formation fluid flows into the wellbore and up to the surface while drilling.
Underbalanced conditions do not allow filter cake build-up and also avoid formation damage due to the invasion of drilling mud and solids into the formation. Drilling rates in Underbalanced Drilling are typically high. In UBD, the influx of formation fluids must be controlled to avoid well-control problems. With the well flowing, the Blow Out Preventor (BOP) system is kept closed while drilling by using a rotating head to ensure maintain control of the well.