glossary

3-D Seismic: a tool used to “see” beneath the earth’s surface. It involves sending acoustic vibrations into the ground and measuring the length of time it takes to rebound off the subsurface rocks back to the surface. High-tech supercomputers are used to process billions of data samples and generate a detailed, 3-D image of underground structures. Geophysicists interpret the data to make estimates as to the depth of the reservoir, its porosity, fluid content and other information valuable in determining where oil and gas deposits are most likely to be found.

Acid stimulation: injecting hydrofluoric acid into the channels of a low permeability reservoir to break up and remove rock debris to help improve the flow of oil.

Appraisal drilling: drilling in the vicinity of a discovery to evaluate the extent of the reservoir and the amount of reserves it likely contains.

Associated gas: gas that is produced along with oil from oil reservoirs. Production originating from gas reservoirs is referred to as non-associated gas.

Barrels of Oil Equivalent (BOE): a term used to quantify oil and natural gas volumes based on “energy equivalents. To convert a thousand cubic feet (Mcf) of gas to equal one barrel of oil, divide by 6. For example, 600 Mcf = 100 BOE.

CO2 Flooding: an enhanced oil recovery technique where carbon dioxide (CO2) is injected into the oil formation. CO2 acts as a solvent that releases the oil from porous rock and causes it to flow more freely to the well head, increasing recovery rates.

Compression: utilized to enhance production from low pressure gas reservoirs. Compression equipment allows the operator to lower back-pressure on the well and enable more gas to flow to the surface. It can then be compressed and delivered into a higher pressure gathering system for processing and ultimate sale. Compression is also used extensively in gas processing operations to aid in the recovery of natural gas liquids.

Development: drilling and related activities necessary to bring a field into production following a discovery.

Dome: a type of geological structure where a rock layer has pushed up into the rock layer above in a typically spherical shape. 

Enhanced Oil Recovery (EOR): advanced technologies, such as water flooding, steam injection, CO2 injection applied to increase production, usually from mature, underdeveloped fields.

Fracture stimulation: injecting specially engineered fluids under high pressure into the channels of a low permeability reservoir to “crack” the reservoir and improve the flow of oil.

HES: Health, Environment and Safety programs.

Horizontal Drilling: drilling a well at a 90-degree angle instead of vertically. The well is drilled straight to a specific depth and then is gradually curved. Horizontal wells are advantageous for numerous reasons: to maximize production rates through increased reservoir exposure; to avoid sensitive environmental areas; to avoid a surface obstruction; or to drill several wells from a single location (i.e. offshore platform). Directional drilling refers to non vertical wells drilled at less than a 90-degree angle.

Interval: a vertical section of rock distinct from that above or below.

In-fill drilling: wells drilled between existing producing wells to enhance field development.

Mcf: a thousand cubic feet, a measurement of natural gas.

Multilaterals: pertaining to a well that has more than one branch radiating from the main wellbore.

Natural Gas Liquids (NGLs): Natural gas processed from and marketed separately, natural gas liquids include ethane, propane, butane and natural gasoline.

Outside operated assets: assets in which Occidental has a working interest, but does not serve as overall operations manager.

Permeable: measure of a rock’s ability to flow liquids or gases. Highly permeable rocks tend to have many large and well-connected pores. The more permeable the rock, the easier it is to produce oil and gas from the reservoir.

Play: an area where oil or natural gas accumulations of a certain type are found.

Porosity: percentage of void space within a rock. Only high porosity reservoir rocks, like sandstone, bear oil and gas. 

Production: oil and gas yielded from drilling and pumping activities. Gross production: the total oil and gas produced from a field. Net production: the company’s share of production based on its ownership interest, or the terms of a production sharing contract.

Recompletion: the process of producing from another interval within the same wellbore. For example, after depleting a zone at 9,000 feet, the operator may “recomplete” the well at 8,000 feet.

Reserves: oil or natural gas contained in underground rock formations called reservoirs.

• Proved reserves: the estimated quantities of oil or natural gas that can be recovered with reasonable certainty.

Reservoir: a porous, permeable rock formation containing oil and natural gas.

Reservoir modeling: a representation of a reservoir that incorporates all data pertinent to its ability to store and produce oil and gas. Geoscientists and engineers use reservoir modeling to simulate the movement of the oil and gas under various circumstances to ultimately determine optimal production techniques for the reservoir.

Spar: a revolutionary type of deep water offshore production facility.

Waterflooding: an enhanced oil recovery technique where injected water is used to sweep residual oil to the wellhead, improving recovery rates.

Wellbore: the hole drilled for the purpose of producing oil and gas, or to inject water or other fluids. In some wells, multilaterals branch off from the main wellbore.

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