Surging

Surging

Definition(s)

Surging

A rapid increase in pressure downhole that occurs when drill stem is lowered too fast or when the mud pump is brought up to speed after starting. Source: API RP 59, Recommended Practice for Well Control Operations, Second Edition, May 2006. Global Standards
Structural Casing

Structural Casing

Definition(s)

Structural Casing

The outer string of large-diameter, heavy-wall pipe installed in wells drilled from floating installations to resist the bending moments imposed by the marine riser and to help support the wellhead installed on the conductor casing. Source: API RP 59, Recommended Practice for Well Control Operations, Second Edition, May 2006. Global Standards  

Structural Casing

The outer string of large diameter, heavy-wall pipe installed in wells drilled from floating installations to isolate very shallow sediments from subsequent drilling and to resist the bending moments imposed by the marine riser and to help support the wellhead installed on the conductor casing. Source: API RP 64, Recommended Practice for Diverter Systems Equipment and Operations, Second Edition, November 2001 (March 1, 2007). Global Standards  

Structural Casing

"Structural casing" means a short string of large diameter pipe that is set by driving, jetting, or drilling to support unconsolidated shallow sediments, provide hole stability for initial drilling operations, and provide anchorage for a diverter system. Source: Alaska Oil and Gas Conservation Commission, Definitions, Alaska Admin. Code tit. 20, § 25.990, December 7, 2012. Regulations  
Stripping

Stripping

Definition(s)

Stripping

A procedure for running or pulling pipe from the well bore with pressure in the annulus. Source: API RP 59, Recommended Practice for Well Control Operations, Second Edition, May 2006. Global Standards  

Stripping

Adding or removing pipe from a pressured wellbore while controlling flow from the wellbore. Source: API SPEC 16RCD, Specification for Drill Through Equipment—Rotating Control Devices, Upstream Segment, First Edition, February 2005. Global Standards  

Stripping

Adding or removing drill pipe into a live or pressurized well after exceeding pipe light depth. Source: IADC UBO / MPD Glossary, December 2011. Global Standards  

Stripping

“Stripping” means pulling or running pipe under pressure through a resilient sealing element and may also include the removing of rods and tubing from the well at the same time. [Mich. Admin. Code R 408 (2013)]. Source: Oil and Gas Drilling and Servicing Operations, Michigan Administrative Code R 408, February 8, 2013. Regulations
Squeezing

Squeezing

Definition(s)

Squeezing

Pumping fluid into one side of the drill pipe/annulus flow system with the other side closed to allow no outflow. Source: API RP 59, Recommended Practice for Well Control Operations, Second Edition, May 2006. Global Standards  

Squeezing

Lateral movement of weak soil between the spudcan base and an underlying stronger layer, or of weak soil between two stronger layers. Source: ISO 19905-1:202, Petroleum and natural gas industries – Site-specific assessment of mobile offshore units – Part 1: Jack-ups. Global Standards  
Space-Out Joint

Space-Out Joint

Definition(s)

Space-Out Joint

The joint of drill pipe used in hang off operations so that no tool joint is opposite a set of preventer rams. Source: API RP 59, Recommended Practice for Well Control Operations, Second Edition, May 2006. Global Standards
Space-Out

Space-Out

Definition(s)

Space-Out

Procedure conducted to position a predetermined length of drill pipe above the rotary table so that a tool joint is located above the subsea preventer rams on which drill pipe is to be suspended (hung-off) and so that no tool joint is opposite a set of preventer rams after drill pipe is hung-off. Source: API RP 59, Recommended Practice for Well Control Operations, Second Edition, May 2006. Global Standards
Sour Gas

Sour Gas

Definition(s)

Sour Gas

Natural gas containing hydrogen sulfide. Source: API RP 59, Recommended Practice for Well Control Operations, Second Edition, May 2006. Global Standards  

Sour Gas

Natural gas containing hydrogen sulfide. Source: API RP 64, Recommended Practice for Diverter Systems Equipment and Operations, Second Edition, November 2001 (March 1, 2007). Global Standards  

Sour Gas

Any natural gas containing more than 1 1/2 grains of hydrogen sulphide per 100 cubic feet or more than 30 grains of total sulphur per 100 cubic feet, or gas which in its natural state is found by the commission to be unfit for use in generating light or fuel for domestic purposes. Source: Oil and Gas Division, Texas Administrative Code, Title 16, Chapter 3, February 2013. Regulations
Soft Close-In

Soft Close-In

Definition(s)

Soft Close-In

To Close-in a well by closing a BOP with the choke and choke line valve open, then closing the choke while monitoring the casing pressure gauge for maximum allowable casing pressure. Source: API RP 59, Recommended Practice for Well Control Operations, Second Edition, May 2006. Global Standards
Shear Rams

Shear Rams

Definition(s)

Shear Rams

BOP rams with a built-in cutting edge that will shear tubulars that may be in the hole. Source: API RP 59, Recommended Practice for Well Control Operations, Second Edition, May 2006. Global Standards
Saltwater Flow

Saltwater Flow

Definition(s)

Saltwater Flow

An influx of formation saltwater into the well bore. Source: API RP 59, Recommended Practice for Well Control Operations, Second Edition, May 2006. Global Standards
Safety Factor

Safety Factor

Definition(s)

Safety Factor

In the context of this publication, an incremental increase in drilling fluid density beyond the drilling fluid density indicated by calculations to be needed to contain a kicking formation. Source: API RP 59, Recommended Practice for Well Control Operations, Second Edition, May 2006. Global Standards  

Safety Factor

"Safety Factor" means the ratio of the ultimate breaking strength of a member or piece of material or equipment to the actual working stress. Source: State of Wyoming Occupational Safety and Health Rules and Regulations for Oil and Gas Well Drilling, Revised January 8, 2013. Regulations  
Rotating Head

Rotating Head

Definition(s)

Rotating Head (or Rotating Drilling Head)

A rotating, low pressure sealing device used in drilling operations utilizing air, gas, or foam (or any other drilling fluid whose hydrostatic pressure is less than the formation pressure) to seal around the drill stem above the top of the BOP stack. Source: API RP 59, Recommended Practice for Well Control Operations, Second Edition, May 2006. Global Standards  

Rotating Head

Low-pressure diverter designed to rotate with drill pipe and used mainly in air drilling. Source: IADC UBO / MPD Glossary, December 2011. Global Standards  

Rotating Head

"Rotating head" means a rotating, pressure sealing device used in drilling operations utilizing air, gas, foam, or any other drilling fluid whose hydrostatic pressure is less than the formation pressure. Source: Corporation Commission, Oil and Gas Conservation, Oklahoma Administrative Code 165:10, February 2013. Regulations
Replacement

Replacement

Definition(s)

Replacement

The process whereby a volume of fluid equal to the volume of steel in tubulars and tools withdrawn from the well bore is returned to the well bore. Source: API RP 59, Recommended Practice for Well Control Operations, Second Edition, May 2006. Global Standards
Productivity Index

Productivity Index

Definition(s)

Productivity Index (PI)

The PI represents one point on an inflow performance curve (IPR) and is defined as the well flow in barrels per day per psi pressure drop. Source: API RP 59, Recommended Practice for Well Control Operations, Second Edition, May 2006. Global Standards  

Productivity Index

The continuous production capacity of a PI is a measure of rate (MSCFD) divided by the pressure drop to generate the flow rate (PSI). Index is MSCFD/PSI or Barrels per day per PSI. Source: IADC UBO / MPD Glossary, December 2011. Global Standards  

Productivity Index (PI)

"Productivity index" means the daily production of oil in barrels per unit pressure differential between the static reservoir pressure and the stabilized flowing pressure during flow at a stated rate. Source: Corporation Commission, Oil and Gas Conservation, Oklahoma Administrative Code 165:10, February 2013. Regulations  
Pressure Gradient

Pressure Gradient

Definition(s)

Pressure Gradient, Normal

The normal pressure divided by true vertical depth. Source: API RP 59, Recommended Practice for Well Control Operations, Second Edition, May 2006. Global Standards  

Pressure Control

Change of pressure with depth, usually expressed as pounds per square inch per foot. A scale of pressure differences in which there is a uniform difference in pressure from point to point. Source: IADC UBO / MPD Glossary, December 2011. Global Standards
Pack-Off

Pack-Off

Definition(s)

Pack-Off (or Stripper)

A device with an elastomer packing element that depends on pressure below the packing to effect a seal in the annulus. Used primarily to run or pull pipe under low or moderate pressures. This device is not dependable for service under high differential pressures. Source: API RP 59, Recommended Practice for Well Control Operations, Second Edition, May 2006. Global Standards  
Overbalance

Overbalance

Definition(s)

Overbalance

The amount by which pressure exerted by the hydrostatic head of fluid in the well bore exceeds formation pressure. Source: API RP 59, Recommended Practice for Well Control Operations, Second Edition, May 2006. Global Standards  
Normal Pressure

Normal Pressure

Definition(s)

Normal Pressure

Formation pressure equal to the pressure exerted by a vertical column of water with salinity normal for the geographic area. Source: API RP 59, Recommended Practice for Well Control Operations, Second Edition, May 2006. Global Standards  

Normal Pressure

"Normal pressure" means a formation pore pressure, proportional to depth, which is roughly equal to the hydrostatic pressure gradient of a column of salt water (.465 psi/ft). Source: Corporation Commission, Oil and Gas Conservation, Oklahoma Administrative Code 165:10, February 2013. Regulations  
Mud-Gas Separator

Mud-Gas Separator

Definition(s)

Mud-Gas Separator

A vessel for removing free gas from the drilling fluid returns. Source: API RP 59, Recommended Practice for Well Control Operations, Second Edition, May 2006. Global Standards  
Marine Riser System

Marine Riser System

Definition(s)

Marine Riser System

The extension of the well bore from the subsea BOP stack to the floating drilling vessel which provides for fluid returns to the drilling vessel, supports the choke, kill, and control lines, guides tools into the well, and serves as a running string for the BOP stack. Source: API RP 59, Recommended Practice for Well Control Operations, Second Edition, May 2006. Global Standards  

Marine Riser System

The extension of the wellbore from the subsea BOP stack to the floating drilling vessel which provides for fluid returns to the drilling vessel, supports the choke, kill, and control lines, guides tools into the well, and serves as a running string for the BOP stack. Source: API RP 64, Recommended Practice for Diverter Systems Equipment and Operations, Second Edition, November 2001 (March 1, 2007). Global Standards  
Lubrication

Lubrication

Definition(s)

Lubrication

Alternately pumping a relatively small volume of fluid into a closed well bore system and waiting for the fluid to fall toward the bottom of the well. Source: API RP 59, Recommended Practice for Well Control Operations, Second Edition, May 2006. Global Standards  
Low Choke Pressure Procedure

Low Choke Pressure Procedure

Definition(s)

Low Choke Pressure Procedure

Consists of circulating and weighting up the drilling fluid, both at the maximum rates, while holding the maximum allowable casing pressure on the choke. Source: API RP 59, Recommended Practice for Well Control Operations, Second Edition, May 2006. Global Standards  
Lost Circulation

Lost Circulation

Definition(s)

Lost Circulation (Lost Returns)

The loss of whole drilling fluid to the well bore. Source: API RP 59, Recommended Practice for Well Control Operations, Second Edition, May 2006. Global Standards  
Kill-Rate Circulating Pressure

Kill-Rate Circulating Pressure

Definition(s)

Kill-Rate Circulating Pressure

Pump pressure required to circulate kill-rate volume under non-kick conditions. Source: API RP 59, Recommended Practice for Well Control Operations, Second Edition, May 2006. Global Standards  

Kill-Rate Circulating Pressure

Pump pressure required to circulate kill rate volume under well kick conditions. Source: IADC UBO / MPD Glossary, December 2011. Global Standards
Kill-Rate

Kill-Rate

Definition(s)

Kill-Rate

A predetermined fluid circulating rate, expressed in fluid volume per unit time, which is to be used to circulate under kick conditions. The kill-rate is usually some selected fraction of the circulating rate used while drilling. Source: API RP 59, Recommended Practice for Well Control Operations, Second Edition, May 2006. Global Standards  

Kill-Rate

A predetermined fluid circulation rate expressed in volume per unit of time that is used under kick conditions, often a selected fraction of the circulating rate time unit used while drilling under normal conditions. Source: IADC UBO / MPD Glossary, December 2011. Global Standards
Kill Drilling Fluid Density

Kill Drilling Fluid Density

Definition(s)

Kill Drilling Fluid Density

The unit weight, e.g., pounds per gallon (lb/gal), selected for the fluid to be used to contain a kicking formation. Source: API RP 59, Recommended Practice for Well Control Operations, Second Edition, May 2006. Global Standards Source: API RP 64, Recommended Practice for Diverter Systems Equipment and Operations, Second Edition, November 2001 (March 1, 2007). Global Standards  
Kelly Valve, Lower

Kelly Valve, Lower

Definition(s)

Kelly Valve, Lower

An essentially full-opening valve installed immediately below the kelly, with outside diameter equal to the tool joint outside diameter. Source: API RP 59, Recommended Practice for Well Control Operations, Second Edition, May 2006. Global Standards  

Kelly Valve, Lower

An essentially full opening valve below the Kelly, with an OD same as the drill pipe.. Source: IADC UBO / MPD Glossary, December 2011. Global Standards
Inflow Performance

Inflow Performance

Definition(s)

Inflow Performance (IPR)

Represents the ability of a well to produce fluids and is typically represented by the curve of a plot of flowing pressure versus flow rate. Source: API RP 59, Recommended Practice for Well Control Operations, Second Edition, May 2006. Global Standards  
Initial Circulating Pressure

Initial Circulating Pressure

Definition(s)

Initial Circulating Pressure

Drill pipe pressure required to circulate initially at the selected kill-rate while holding casing pressure at the closed-in value; numerically equal to kill-rate circulating pressure plus closed-in drill pipe pressure. Source: API RP 59, Recommended Practice for Well Control Operations, Second Edition, May 2006. Global Standards  
Influx

Influx

Definition(s)

Influx

The flow of fluids from the formation into the well bore. Source: API RP 59, Recommended Practice for Well Control Operations, Second Edition, May 2006. Global Standards