Drilling operations glossary — English and Arabic

Term	Category	Definition
Invisible lost time (ILT) الوقت الضائع غير المرئي	Performance	The gap between how long a routine drilling operation took and how long it should have taken against a benchmark. It sits inside productive time, so it never appears on the morning report or in the NPT ledger. Published studies place it at a fifth or more of total well time, typically several times larger than recorded non-productive time.
Non-productive time (NPT) الوقت غير المنتج	Performance	Time during which planned operations stop — equipment failure, stuck pipe, waiting on weather, well control. It is recorded, coded and charged to an account. Usually under 5% of a well.
Weight to weight (W2W) من وزن إلى وزن	Performance	The connection time measurement used across the industry: from the moment the driller sets the string in the slips to the moment weight is back on bottom. The most reliable single indicator of rig floor performance because it is repeated hundreds of times per well.
Slips to slips من الأسافين إلى الأسافين	Performance	An alternative connection measurement bounded by the slips being set and released. Narrower than weight to weight and less useful for benchmarking because it excludes the drilling-ahead transition.
Flat time الوقت الثابت	Performance	Time when the bit is not making hole but the operation is proceeding as planned: casing runs, cement waiting on setting, BOP nipple-up and testing, rig moves, logging. Often the largest single block of a well and largely under the drilling contractor's control.
Rate of penetration (ROP) معدل الاختراق	Performance	The speed at which the bit makes hole, in metres or feet per hour. On-bottom ROP excludes connections and other interruptions; average ROP includes them.
Tripping الرحلة	Operations	Running the drill string into or out of the hole. Measured per stand, and separately for cased and open hole, because the two behave differently.
Stand الوحدة الأنبوبية	Operations	Two or three joints of drill pipe left connected and racked in the derrick. The unit in which tripping speed is measured.
Tour النوبة	Operations	A work shift on a drilling rig, usually twelve hours. The tour sheet is the driller's record of what happened during it, and the primary source document for every downstream report.
Tour sheet ورقة النوبة	Documents	The driller's handwritten or digital record of the shift: depths, activities against IADC codes, mud properties, connections, personnel and remarks. Everything in the daily drilling report is built from it.
Daily drilling report (DDR) التقرير اليومي للحفر	Documents	The 24-hour summary of operations issued to the operator. The IADC format is the contractor's version; most operators also require their own format, which is why the same day is frequently typed out twice.
IADC time and operation codes رموز العمليات والوقت	Standards	The International Association of Drilling Contractors' standard coding scheme for classifying rig activity and lost time. Using it consistently is what makes performance comparable between rigs, wells and contractors.
Kill sheet ورقة القتل	Well control	The pre-calculated well control worksheet holding kill mud weight, initial and final circulating pressures and the pressure step-down schedule. Required to be current for the section being drilled.
Slow circulating rate (SCR) معدل الدوران البطيء	Well control	Pump pressure measured at a reduced rate, recorded for use in well control calculations. Taken each tour, each section and after any significant mud change.
Shut-in drillpipe pressure (SIDPP) ضغط الأنبوب المغلق	Well control	The stabilised drill pipe pressure after a well is shut in on a kick. Used to calculate the kill mud weight.
Maximum anticipated surface pressure (MASP) أقصى ضغط سطحي متوقع	Well control	The highest pressure expected at the wellhead in a credible worst case. Sets the required pressure rating of the BOP stack and wellhead.
Blowout preventer (BOP) مانع الانفجار	Equipment	The stack of hydraulically operated valves that closes the well in. Rated by bore and working pressure, and tested on a fixed cycle under API STD 53.
Annular preventer المانع الحلقي	Equipment	The BOP element that seals around any shape in the hole, or on open hole. Usually the first element closed and the lowest pressure rated in the stack.
Blind shear ram الكباش القاطعة	Equipment	The BOP rams that cut the drill pipe and seal the bore. The last line of defence in a well control event.
Drawworks الرافعة	Equipment	The rig's hoisting machine. Its power rating in horsepower, together with hookload and mast rating, defines the depth a rig can drill.
Hookload حمل الخطاف	Equipment	The total weight suspended from the hook. Its rating limits the heaviest casing string a rig can run, and it is the primary sensor channel for detecting a connection.
Mast rating (API 4F) تصنيف البرج	Standards	The certified capacity of the derrick or mast under API Spec 4F, with and without pipe racked. A rig can be power-adequate and still fail on mast rating.
Casing التغليف	Well construction	Steel pipe cemented into the wellbore to isolate formations and support the well. Specified by outside diameter, weight per foot, grade and connection under API Spec 5CT.
Design factor معامل التصميم	Well construction	The ratio of a casing string's rated capacity to the load it must carry, calculated separately for burst, collapse and axial tension. Minimums are set by the operator's own standard.
Casing shoe حذاء التغليف	Well construction	The bottom of a cemented casing string. Its depth sets where the next hole section begins and where formation integrity is tested.
Leak-off test (LOT) اختبار التسرب	Well construction	A test below the casing shoe that pressures the formation until it begins to take fluid, establishing the fracture gradient and therefore the mud weight window for the next section.
Formation integrity test (FIT) اختبار سلامة التكوين	Well construction	A test to a predetermined pressure below leak-off, confirming the formation will hold the planned mud weight without establishing the actual fracture gradient.
Mud weight window نافذة وزن الطين	Well construction	The range between pore pressure and fracture gradient at a given depth. Drilling outside it means either an influx or losses. Narrow windows are the usual reason for an extra casing string.
Pore pressure ضغط المسام	Subsurface	The pressure of fluid held in the formation. Mud weight must exceed it to keep the well stable, and must stay below fracture gradient.
Fracture gradient تدرج التكسير	Subsurface	The pressure at which the formation breaks down and takes fluid. The upper limit of the mud weight window.
Dogleg severity (DLS) شدة الانحناء	Directional	The rate at which a wellbore changes direction, in degrees per 30 metres or 100 feet. Excessive DLS causes casing wear, torque and drag, and running problems.
Kick-off point (KOP) نقطة بدء الانحراف	Directional	The depth at which a well begins to deviate from vertical.
Minimum curvature method طريقة أقل انحناء	Directional	The standard survey calculation method, assuming a circular arc between survey stations. The basis of every modern trajectory and anti-collision calculation.
Measured depth (MD) and true vertical depth (TVD) العمق المقاس والعمق الرأسي	Directional	MD is distance along the wellbore; TVD is vertical distance below datum. Formation pressures are always evaluated on TVD; casing depths are always recorded as MD. Confusing the two is a common and consequential error.
Anti-collision تجنب التصادم	Directional	The analysis proving a planned wellbore maintains adequate separation from every offset well, using survey uncertainty models under the ISCWSA standard.
WITS (Wellsite Information Transfer Specification) مواصفة نقل معلومات الموقع	Data	The IADC-originated specification for transmitting rig sensor data. WITS Level 0 is a simple serial record format still in wide use and sufficient for connection and tripping analysis.
WITSML لغة ترميز معلومات الموقع	Data	The XML-based Energistics standard for exchanging wellsite data, richer than WITS and used for logs, trajectories, mud and cuttings as well as time-based channels.
Electronic drilling recorder (EDR) المسجل الإلكتروني للحفر	Data	The rig-site system that acquires, displays and records sensor data. The source of the WITS feed a performance system reads.
Managed pressure drilling (MPD) الحفر بالضغط المُدار	Techniques	Drilling with precise control of annular pressure through a rotating control device, allowing narrow mud weight windows to be drilled that conventional mud alone cannot.
Rotary steerable system (RSS) نظام التوجيه الدوار	Techniques	A directional tool that steers while the string rotates continuously, producing better hole quality and higher ROP than a bent-housing motor.
Workover إعادة تأهيل البئر	Intervention	Any major intervention on an existing well: tubing replacement, pump change, zone isolation, recompletion or abandonment.
Snubbing unit وحدة الإنزال تحت الضغط	Intervention	The heaviest live-well intervention method, using hydraulic jacks to force pipe into a well against pressure that would otherwise eject it. Used when wireline and coiled tubing lack the strength.
Hydraulic workover unit (HWO) وحدة إعادة التأهيل الهيدروليكية	Intervention	A jack-based unit that runs and pulls tubulars against wellbore pressure without killing the well, protecting pressure-sensitive reservoirs from damage.
Coiled tubing الأنبوب الملفوف	Intervention	Continuous pipe run from a reel without making connections. Used for cleanouts, stimulation, milling and fishing, particularly in deviated and horizontal wells.
UIC Class II well بئر الحقن من الفئة الثانية	Well types	Under the US Underground Injection Control framework, a well injecting fluids associated with oil and gas production — produced water disposal and water or gas injection for recovery. The most numerous injection well class in the world.
UIC Class VI well بئر تخزين ثاني أكسيد الكربون	Well types	An injection well for geologic sequestration of carbon dioxide, with materials, monitoring and post-closure obligations well beyond a conventional injector.
Authority for expenditure (AFE) تفويض الإنفاق	Commercial	The approved budget for a well. Days recovered against AFE are the commercial measure a drilling contractor is judged on.
In-Country Value (ICV) القيمة المحلية المضافة	Commercial	The UAE and Oman procurement scoring framework rewarding local spend, employment and capability. Affects how software is contracted and where it is hosted.