Nostra Terra is an oil and gas exploration and production company listed on the AIM, a market operated by the London Stock Exchange (LSE: NTOG)

Focused on achieving profitable, rapid and sustainable growth, which generate returns for our shareholders, we have a diverse and growing portfolio of producing and exploration assets with capital in place to continue development.

In this section, you will find links to information for all existing and potential shareholders.




O&G Glossary

Crude oil

A mixture of liquid hydrocarbons of different molecular weight, containing different levels of impurities such as sulphur, water.

Decline Curve Analysis (DCA)

A graphical procedure used for analysing declining production rates and forecasting future performance of oil and gas wells. Oil and gas production rates decline as a function of time; loss of reservoir pressure, or changing relative volumes of the produced fluids, are usually the cause.

Depositional Environment

The conditions under which a series of rock strata were laid down. Depositional environments can be divided into six subgroups: marine, lagoonal, deltaic (laid down by a river at its delta), alluvial/fluvial (laid down by a river), lacustrine (laid down under a lake) and aeolian (laid down by wind).

Depreciation, depletion and amortisation (DD&A)

The release of capitalised hydrocarbon assets to the income statement over their economic useful lives.


The tower-like structure that houses most of the drilling controls.

Derrick man

The labourer that works at the top of the derrick and helps guide drill pipe to its correct position during drill pipe makeup. Is sometimes replaced by electro-mechanical systems on more modern rigs.


Process used to remove/separate contaminants such as inorganic salts found in crude oil. Also referred to as dehydration.

Developed acreage

The number of acres that are allocated or assignable to productive wells or wells capable of production.

Developed reserves

Reserves that can be expected to be recovered through existing wells with existing equipment and operating methods or in which the cost of the required equipment is relatively minor compared to the cost of a new well and, if extraction is by means other than a well, through installed equipment and infrastructure operational at the time of the reserves estimate.

Development costs

Costs of constructing and installing the facilities to produce and transport the oil and gas the pressure at which liquid comes out of solution in a gas condensate.

Development well

A well drilled within the proved area of an oil or gas reservoir to the depth of a stratigraphic horizon known to be productive

Directional drilling

The art of guiding the drill bit to a target that is not vertically below the drill floor. Downhole mud motors, special stabilisers, MWD and LWD sensors and telemetry (communications system) can all be used to increase accuracy.


The process via which the various components of crude are separated into groups of hydrocarbon compounds on the basis of the difference in relative boiling points. Distillation can be atmospheric or vacuum. Also known as topping or skimming.


A metal shack used for storing equipment and working in.

Donkey dick

The rubber guide placed beneath wireline logging tools that help them get past well bore obstructions when being lowered to total depth.


Includes oil refineries, petrochemical plants, petroleum product distribution, retail outlets and natural gas distribution companies.

Draw works

The winch that pulls on the steel cable that in turn raises and lowers the travelling block in the derrick.


The large rotating drum that spools the drilling line in and out to raise the load on a drilling rig.

Drill collar

Heavyweight drillpipe that goes on the bottom of the drill string to provide weight-on-bit and stability.

Drill pipe

Pipe that connects drillfloor torque to the drill collars and ultimately the drill bit. Drill pipe is hollow to allow mud to circulate through it.

Drill string (drill pipe)

Comprises lengths of drill pipe and drill collars that connect the drill bit with the drilling rig. The drill string is used to rotate the drill bit and to act as a conduit to circulate drilling mud to the cutting face.


The person responsible for drilling a decent hole by constantly monitoring and adjusting drill pipe torque and weight-on-bit.

Drilling fluid

See 'mud'.

Drilling rig

Any kind of drilling unit (i.e. land, submersible, semi-submersible, jack-up or drill ship). Also incorporates the derrick and its associated machinery.

Dry hole

See ‘duster’.


A well that fails to find any commercial oil or gas.

Economically producible

A resource that generates revenue that exceeds, or is reasonably expected to exceed, the costs of the operation.

Enhanced Oil Recovery

Increases hydrocarbon recovery by maximising displacement efficiency in a cost-efficient manner. Methods include thermal EOR, flooding the reservoir with various substances or Microbial EOR.

Estimated Ultimate Recovery (EUR)

A production term commonly used in the oil and gas industry. EUR is an approximation of the quanity of oil or gas that is potentially recoverable or has already been recovered from a reserve or well.

Exploratory well

A well drilled to find a new field or to find a new reservoir in a field previously found to be productive of oil or gas in another reservoir.


A term sed to describe when an oil company buys a portion of the acreage in a block from another company, usually in return for cash and for taking on a portion of the selling company's work commitments.


A fracture along which the rocks on one side are displaced relative to those on the other.

Fault trap

These are created when a reservoir layer such as sandstone is faulted and juxtaposed against an impervious rock which thus prevents the migration of hydrocarbons leading to oil or gas accumulations against the fault.


A geographical area under which an oil or gas reservoir lies

Field Development Plan (FDP)

FDPs provide the necessary support for field optimisation, and include all activities and processes required to optimally develop a field. In general, development activities and processes involve environmental impact, geophysics, geology, reservoir and production engineering, infrastructure, well design and construction, completion design, surface facilities, economics and risk assessment.

Finding costs

The costs of exploration and appraisal programmes i.e. how much did its cost the company to find each barrel of oil actually added to reserves in the year.


A procedure whereby drillpipe is used to retrieve items lost in the hole - e.g. a dropped spanner, clamp, wireline instruments or even other drillpipe. It can consume great amounts of time, can be dangerous and is universally hated (except by fishing consultants).

Flow rate

The rate at which hydrocarbons flow up through the oil well. The rate is expressed in terms of bbls/day for oil and SCF/day for gas.


A rock layer which has distinct characteristics (e.g. rock type, geologic age).


That part of petroleum separated off from other parts at a particular boiling range.