D
D&A Dry and Abandonned (well)
DAC Distance Across Course
Distance Amplitude Correction
DAF Dynamic Amplification Factor
DAMA Demand Assigned Multiple Access
DANIDA  Danish International Development Assistance
DAPC  Dynamic Annular Pressure Control 
DATR  French regulation related to workers exposed to ionizing radiations
Stands for : Directement Affecté aux Travaux sous Rayonnements 
DART Design, Application and Research Team
DAS Data Acquisition System/Subsystem
db  dry bulb temperature 
dB  sound pressure level in decibels and measurement of attenuation in signal/communications lines 
DBB  Double Block and Bleed (valve system)
DBS Duty / Back-up / Stand-by
DC Direct Current
dc delayed-action coker 
DCBC  Diver Certification Board of Canada 
DCC Distance Cross Course
DCDB  IHO Data Center for Digital Bathymetry website
DCI Decompression illness
DCQ Daily Contract Quantity 
DCR  Design and Construction Regulations (SI 1996/913) 
DCS Distributed Control System
Digital Control System
  Drill Collars
  Decompression Sickness
DCU Dry Completion Unit 
DCV Directional Control Valve
DCWR  Drilling Completions and Work-over Rig 
DD  Detailed Design 
DDC Deck Decompression Chamber
DDCU Deep Draft Caisson Unit
DDR  Deliverable Documents Register 
DDV  Downhole Deployment Valve 
DDCV Deep Draft Caisson Vessel
DID Direct Inward Dialling
DECT Digital Enhanced Cordless Telecommunication
DEG  DuoEthylene Glycol 
DEM  Demulsifier 
DEMA  Diesel Engine Manufacturers Association (USA/ ASME) 
D En   Department of Energy (UK) - also DEn / D.En  
DENL  Density Log 
DEP Design and Engineering Practice 
depl Depletion
DERA  Defence Evaluation and Research Agency (UK)
DESIGN  Diving Equipment System Inspection Guidance Notes (IMCA) 
DETR  Department of the Environment, Transport and the Regions (UK) 
DFI Design Fabrication Installation
  Deep Foundations Institute (USA)
DFID  Department for International Development (UK)
DFX Dimensional Fx
DGEMP  Direction Générale de l'Énergie et des Matières Premières
DGN MicroStation Design File (file format/extension)
  Degrees Grid North
DGPS Differential Global Positioning System
DHFC Down Hole Flow Controler
DHI Deutsche Hydrographische Institut 
DHPG  Down Hole Pressure Gauge 
DHPT Down Hole Pressure and Temperature transmitter
DHSS Down Hole Safety System
  Department of Health & Human Services (multiple states)  
  Department of Health & Social Security (UK, from 1968 until 1988)  
DHSV Down Hole Safety Valve
DHSV (U) Upper Down Hole Safety Valve
DHSV (L) Lower Down Hole Safety Valve
DI Digital Input
D&ID Ducting & Instrument Diagram
DIRECT Diverless Inspection and Repair Using an Electro-Chemical Technique UK/Norway research project
DISA  Data Interchange Standards Association (USA)
DIMAH   Direction des Matières premières et des Hydrocarbures
DIN Deutsche Institute für Norming
DIS Draft International Standard (ISO)
DISH  Deep Installation of Subsea Hardware 
DIU Down hole Interface Unit
DL Document List
  Density Log 
  Develoment Licence 
DLat  Difference in Latitude 
DLong  Difference in Longitude 
DLN Dry Low NOx (NOx reduction technology)
DMA Dead Man Anchor
DMAC Diving Medical Advisory Committee
DMDO Distilate Marine Diesel Oil 
DMFC Direct Methanol Fuel Cell
DME Distance Measurement Equipment
  Direction-biaised Motion Estimation
DMO Directorate of Maritime Operations ( UK Coast Guards Agency - MCA)
DMS Document / Data Management System
DMT  Diver Medic Technician  
DMTA Dynamic Mechanical Thermal Analysis
DNC Digital Nautical Chart 
DNV Det Norske Veritas
DO Diesel Oil
  Digital Output
DOALOS Division for Ocean Affairs and the Law of the Sea 
DOC Document Of Compliance (as per ISM Code) 
DOE Department Of Energy (US)
DOI  Department Of  Interior (US) 
DOL  Direct On Line (method of connecting and starting electric motors)
DOT Department Of Transport (US)
DOWR Diving Operations at Work Regulations (UK 1997)
DP Dynamic Positioning
  Differential Pressure
  Design Pressure
DPAH Draught Pressure Alarm High
DPI Dye Penetrant Inspection
  Dots per Inch
  Desired Point of Impact
  Detected Pulse Interference
  Differential Pressure Indicator
DPM  Dynamic Pressure Module 
DPR Daily Progress Report
  Department of Petroleum Resources  (DPR a division of NNPC
DPSK Differential encoded PSK (Phase Shift Keying)
DPSWG  CHRIS Data Quality Working Group on ENC data protection
DPVOA Dynamic Positioning Vessel Owners Association (merged with AODC into IMCA)
DQWG    CHRIS Data Quality Working Group on Data quality
DR  Dead Reckoning
DRAMMS  Deepwater Reliability Availability and Maintenance Management System 
drk Derric 
drl  Drill
DRTI Discontinuously Reinforced Titanium
DS Data Sheet
  Drill Stem 
  Directional Survey 
DSAW  Double Submerged Arc Welding / Welded 
DSC Differential Scanning Calorimeter
  Digital Selective Calling 
  Dangerous goods, Solid cargoes and Containers,IMO 
DSCM Dummy Subsea Control Module 
DSCS  Duplex Self-Cleaning Strainer 
DSEAR  Dangerous Substance and Explosive Atmosphere Regulations  
DSL  Direct Shuttle Loading 
DSM Demand-Side Management
  Diving Safety Memorandum 
DSP Digital Signal Processor 
DSDP Deep Sea Drilling Project
DSS  Decision Support System
DST Drill Stem Test
DSTL Defence Science and Technology Laboratory, an agency of the UK Ministry of Defence 
dstl  Distillate
DSV Diving Support Vessel
DSWP  Deterministic Sea Wave Prediction 
DT Design Temperature
D&T Drilling and (well) Test cost
DTCU Digital Turbine Control Unit
DTD Driller's Total Depth 
DTHT Drill Through Horizontal Tree
DTI  Department of Trade and Industry(UK)
DTM Digital Terrain Model
DTMF Dual Tone Multi-Frequency
DTp  Department of Transport 
DTS Distributed Temperature Sensitivity
DTU Data Terminal/Transfer/Transmission Unit
  Dry Tree Unit
Digital Tracking Unit
  Digital Transmission Unit
  Documents Techniques Unifiés (french)
DUQ Drilling, Utilities and Quarters (platform)
DV Directional / Diverter Valve
DVECS  Distributed Vehicle Control System 
DVR Data Video Recorder
DWO  Drilling With Oil 
DWP  Design Working Pressure 
DWT  Dead Weight Tonnage 
DWTT Drop Weight Tear Test
dwks Drawworks 
DWV Drain, Waste and Vent
DX.90  Format for digital cartographic data