D

Dateometer: A small calendar disc attached to motors and equipment to indicate the year in which the last maintenance service was performed. Datum: A relative comparison point, such as the kelly bushing, sea level, or mud line. Daughter: An atom that results from the radioactive decay of a parent atom. Daylight Tour: Day working shift. DB: Dump bailer. DB&B: Double block and bleed. DBP: See Disinfection by-product. DC: Depth correction. DC: See Direct current. DC (Drilling): Drill collar. DCF (Accounting): Discounted cash ¤ow. DCQ: See Daily contracted quantity. DCS: Distributed control system. DCS (Pipe): Depth control sub. DCU: See Dry completion unit. DD: Draw down. DD&A: Depletion depreciation and amortization. DDB: Drive down bailer. DDCV: Deep draft caisson vessel. DDDC: See Dedicated design day capacity. DDR: Daily drilling report. DE: Drilling engineer. Dead Carbon (Shale): Carbon with a type of kerogen content that has low potential to generate hydrocarbons (generally woody carbon). Dead Freight: Space booked by shipper or charterer on a vessel but not used. Dead Freight Factor: Percentage of a ship’s carrying capacity that is not utilized. Dead Leg (Pipeline): A section of pipeline that is not in use. Dead Line (Lift Systems): That part of a wire line or cable that is attached to  a  xed anchor point and does not move through a pulley or other mechanical device. Deadman: Buried anchor. Dead Oil: Crude oil without gas. May have been degassed mechanically or by gas breakout during storage. Dead Time: In radioactive logging, the length of time that the system requires to recover after counting an event. Deadweight: Is the weight in tons that an oil tanker can carry. Deadweight Tonnage: (1) A common measure of ship carrying capacity. (2) The number of tons (2,240 lb) of cargo, stores, and bunkers that a vessel can transport. (3) The difference in weight between a vessel when it is fully loaded and a vessel when it is empty (in general transportation terms, the net) measured by the water it displaces. This is the most

common, and useful, measurement for shipping as it measures cargo capacity. (4) The difference between the number of tons of water a vessel displaces “light” and the number of tons it displaces when submerged to the “deep load line.” A vessel’s cargo capacity is less than its total deadweight tonnage (DWT). Dead Well: A well that will not ¤ow on its own through natural gas lift or by reservoir pressure. Deaerator: Devices used to separate gases from liquids. Deal: Managed by CDA, a unique index of the source of released and proprietary well, seismic and other data. Dealloying (Corrosion): Selective corrosion of one metal in an alloy. Dean Number: Fluid ¤ow effects in spooled tubing. Deasphalting: Process for removing asphalt from petroleum fractions, such as reduced crude. Debottlenecking: (1) Increasing production capacity of existing facilities through the modication of existing equipment to remove throughput restrictions. Debottlenecking generally increases capacity for a fraction of the cost of building new facilities. (2) The process of increasing the production capacity of existing facilities through the modication of existing equipment to remove throughput restrictions. (3) A program, typically in surface facilities and lines, to remove pressure drop causing ¤ow restrictions. Debutanizer: The fractionating column in a natural gasoline plant in which the butane and lighter components are removed overhead. The gas stream remaining is referred to as debutanized. Decay Rate: The rate at which a population of radioactive atoms decays into stable daughter atoms. Rate expressed in half-life of the parent isotope. Decentralizing Arm: A mechanical level that pushes a tool against the side of the well. Dechlorination: The deliberate removal of chlorine from water. The partial or complete reduction of residual chlorine by any chemical or physical process. Decision Tree (Risk): A sequence of nodes that are either a decision or an uncertainty and outcomes associated with each mode. The purpose of a decision tree is to dene the set of scenarios and the sequence of events that guide the evaluation of risk and return. Decline Curve: The slope of the production rate vs. cumulative time or volume measurement. The decline of a well predicts how fast it is being depleted. Decommission: To remove from service. Decommissioning: The process for removal of a plant or piece of equipment from an operational state. Decomposition: The breakdown of complex material into simpler substances by biological or chemical action. Also referred to as degradation.