They failed the FIT, and now they are WOW. Last week they were RIH, but subsequently had to POOH to go Fishing. The sidetrack failed shortly after kick-off. Finally they decided to P&A and skid to a new location.
Is your head spinning yet? Welcome to the wonder world of Wellsite Words; an incomprehensible stream of acronyms, to a lay person.
The first time you attend a meeting offshore is always a memorable experience. Feeling like a fish out of water among seasoned rig personnel. The information exchanges in this fast-paced environment are often rapid, to keep up with the constantly evolving situation. To facilitate this, a lot of the cumbersome long-winded terminology is abbreviated to acronyms. Useful to keep things snappy, but unintelligible jargon if you are a newbie.
We have compiled a list of common operations and drilling terms that may be useful during your first trip offshore. Before you know it, you will be spouting the jargon and acronyms like a pro!
Glossary of commonly use terms in the offshore environment
This glossary is meant to provide an entry level knowledge of common terminology used at wellsite, covering words you may encounter when discussing drilling and rig operations. These are commonly used in meetings, or you may overhear the rest of the crew talking about these.
General wellsite operations glossary
Blowout – uncontrolled influx of gas or formation fluids into the annulus and to the surface. A blowout is prevented by having a BOP.
Bugman (or Bugwoman!) – an affectionate term for a biostratigrapher or palaeontologist on a rig!
Casing – Running steel pipe into a drilled section of a well. This barriers off the drilled open hole formations to allow for further drilling and future production from the reservoir. Biostratigraphy can be used to ‘pick’ a casing point.
Cementing – Application of cement to parts of the wellbore, typically in/around casing or at the end of the well during plugging/setting a shoe.
Circulating – Using the rig pumps to pump drilling mud down the drill string and up through the wellbore, without any active drilling taking place. This enables cleaning of the well by flushing cuttings to the surface.
Coring – Continuous sections of rock cut from the formation in a coring barrel, which can be brought to the surface as a single piece.
SWC – Sidewall Cores are plugs of rock cut from the wellbore wall, usually acquired by wireline-conveyed tools.
Displacing – This operations involves displacing the mud contents of the well with a new mud, which is likely of a different weight and density, using the rig pumps.
Drilling – Creating new wellbore by action of cutting rock fragments from the formation being drilled.
Fishing – Removing a detached object or stuck equipment from the wellbore, with specialised extraction tools. This may include broken drill string, drill bit fragments or any object accidentally dropped into the open hole.
FIT – Formation Integrity Test. This is the first step after drilling out the shoetrack of a cemented and cased section. It provides an evaluation of the cement job and the formation ahead. The new formation is pressurised to a known level to allow for the development of the mud programme for the next section. The new mud weight must lie between the pore pressure and the formation fracture gradients.
Flowcheck – Turning off the pumps to monitor any gains or losses in the active mud system.
Geosteering – This is the process of adjusting the borehole position (inclination and azimuth) to reach one or more geological targets.
Liner – Similar to Casing; a string of steel tubing that does not extend to the top of the wellbore, but instead is anchored from inside the bottom of the previous casing string.
Logging – Combination of rock cuttings analyses, gas analysis and drilling tools which measure the physical parameters of the formations being drilled. Can be done whilst drilling (LWD or MWD) or through running tools on a wireline post-drilling.
RIH – Running In Hole. Returning the drill bit and drill string back into the hole. Follows tripping out.
Running or pulling riser – When drilling offshore the riser provides a barrier between the drill string and the open water and allows for the drilling fluids to return to the surface. The operation of running or pulling the riser is to return the riser (in sections) to the seafloor/BOP and surface.
Sidetrack – A planned deviation from the main wellbore, to produce a newly drilled section.
Skidding – Moving/relocating a rig, from the location of a lost or completed hole. This is a preparatory stage to drilling a new hole nearby. The rig is moved is with little or no dismantling of equipment.
P&A – Plug And Abandoned after unsuccessful well testing or to allow for further development at a later date.
POOH – Pulling Out Of Hole. Also known as Tripping Out. Removing the drill string and drillbit from the hole. This may occur when the drillbit needs changing, tool failures, end of the section/TD or prior to a coring/logging run.
Pressure testing – This is a regular drill conducted to prove the BOP is functioning correctly and providing the correct barrier between the rig and the wellbore.
WOW – Waiting On Weather. Operations on hold due to weather-related challenges.
Drilling terms glossary
BOP – Blowout preventer. A mechanical device connected to the wellhead to prevent blowouts (uncontrolled releases of pressure from the well)
Bottoms up (BU) – Last sample of previously drilled section to the surface after a known lag time.
Borehole – The hole created by drilling, which has not been cased off yet.
BHA – Bottom hole assembly. This is the lowest part of the drilling string, from the bit to the start of the drill pipe, consisting of a mix of stabilisers, shocks, reamers and MWD tools.
Casing shoe – The bottom of the casing string, which is usually rounded to allow for the easy run of the casing. Also includes the cement around it after cementing.
Derrick – The tall pyramidal structure used to suspend the top drive and drill string.
Drillstring – The column of pipe that transmits drilling fluid and torque from the top drive/rotary table/kelly drive to the drill bit.
Drill bit – The tool at the end of the drill string which is used to crush or cut rock.
Drilling break – A change in ROP due to entering a new rock formation/lithology.
Geophysical log – A plot displaying the physical parameters (density, porosity, clay content, fluid & gas content etc.) of the formation drilled. What the plot displays depends on what tools have been run in the hole.
Inclination – The deviation of the wellpath from vertical, irrespective of compass direction, expressed in degrees. Inclination maybe 90 degrees for horizontally drilled and biosteered wells.
MD – Measured depth. This is the length of the wellbore along its path.
Mud – Slang term for drilling fluid.
MWD – ‘Measurement Whilst Drilling’. The evaluation of physical properties (pressure temperature, wellbore trajectory etc.) in a three-dimensional space whilst extending the wellbore. Measurements are made downhole, stored in a solid-state memory and transmitted to the surface through pressure pulses in the mud. MWD tools that measure formation parameters (resistivity, porosity, gamma ray etc.) are referred to LWD (Logging Whilst Drilling tools).
OBM – Oil-based mud.
SBM – Synthetic based mud.
ROP – Rate of Penetration of new formation by the drill bit. Measured in ft/hr or m/hr.
Spud / Spud date – Start/Date of first returns.
Stand – Connected lengths of pipe used for drilling. These are typically 90ft (27.4m) and consist of 3 x 30ft pipes or ‘singles’.
Standpipe – Pipe that provides a high pressure pathway for drilling mud to travel up the derrick to the Kelly hose (flexible high pressure hose to the top drive).
TD – Total depth. Or finished depth corresponds to the end of the well.
TVD – Total vertical depth. This is the vertical distance of the well from the surface, independent of well path.
Wellbore – The drilled hole, including the open hole or uncased portion of the well.
Wellhead – The surface termination of a well bore, including the facilities for installing casing hangers, production tubing, and surface flow-control equipment.
