Abyssal plain (Geology)

(Also Abyss) Abyssal plain is a relatively smooth, large and flat area typically found at the end of the continental rise and right before the mid-ocean ridge. Abyssal plains are Continue reading

Back off (Drilling)

Back-off is a term used anytime any section of the drillstring (drillpipe, drillcollar, or even the drillbit) is unscrewed downhole. This could happen intentionally or by chance. During drilling, some Continue reading

Backreaming (Drilling)

Backreaming is a tripping-out technique in which the drillstring is rotated and circulation is maintained while pulling out of the hole (POOH). Standard tripping out procedure requires the pumps to Continue reading

Bactericides (Drilling Fluids)

(Also biocide) Bactericide is a fluid additive that can and will kill bacteria, algae and other microbial contaminations. Examples of these microorganisms include Penicillium spp., Fusarium spp., Cladosporium sp., Rhizopus Continue reading

Caliper log (Drilling)

Caliper log is a tool lowered into a borehole to measure the diameter and shape of the hole as a function of depth. Data, about borehole diameter and shape, obtained Continue reading

Cap rock (Geology)

Cap rock is a rock that forms a laterally continuous impermeable seal above and around a hydrocarbon reservoir such that hydrocarbon fluids become trapped below the rock. Cap rock detection Continue reading

Dead Oil (Geology)

(Also dead crude) An oil sample is pronounced “dead” when it has lost all its dissolved gases and volatile components. The gaseous components of crude oil are mainly methane, ethane, Continue reading

Decommissioning (Facilities)

Decommissioning represents all the activities involved when removing offshore rigs from service and ensuring that the drilled wells are safely plugged and abandoned. Every oil and gas well has a Continue reading

Drill-in fluid (Drilling)

Drill-in fluid is a special kind of drilling fluid designed to be used only when drilling through the payzone. A drill-in fluid is expected to be non-damaging to the producing Continue reading

Gas cut mud (Drilling)

Gas cut mud is any drilling mud which is found to contain gases after drilling through porous underground formations containing gas. The presence of “foreign” gas within the mud reduces Continue reading

Hook load (Drilling)

Hook load is the sum total of all the downward forces pulling on the hook. This hook is normally attached to the bottom of the travelling block and has a Continue reading

Kelly (Drilling)

Kelly is a steel pipe usually about 40ft long resembling a normal drillpipe except that where a drillpipe has a round (cylindrical) outer body; a kelly can come in a Continue reading

Kelly Bushing (Drilling)

(Also Rotary bushing, Drive Bushing) Kelly bushing is that elevated device positioned right on top of the rotary table and used to transmit torque from the rotary table to the Continue reading

Keyseat (Drilling)

A keyseat is a smaller hole (groove), almost the same diameter as the drillpipe, created in the borehole as the drillpipe rotates against one side of the borehole wall for Continue reading

Kick (Drilling, Well Control)

A kick is a well control problem resulting when formation fluids unexpectedly rush into the wellbore during a drilling, well completions or well intervention operation. The formation fluid “kicking” into Continue reading

Lag gas (Drilling)

Lag gas, with respect to lag time determination, is any non-interacting gas deliberately injected into the drilling fluid, pumped down the drillpipe along with the drilling fluid and allowed to Continue reading