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How to Read a Daily Drilling Report

A Beginner's Guide to Understanding Data on a Daily Drilling Report

The How To Read a DDR resource is a non-technical beginner’s guide to reading and interpreting a Daily Drilling Report produced by a typical onshore E&P operator. It contains common industry acronyms, abbreviations, and terms.

“WellEz sends thousands of reports each day to investors, working interest owners, and non-engineering staff on behalf of our customers. This guide is an invaluable resource to those not versed in common oilfield terms.”
— James Morley, Director of Customer Success

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Daily drilling reports come in many different variations that will change depending on drilling type, operation area, formation type, and company culture. The DDR that we have selected for this resource combines the most common aspects found with US-based onshore drilling operations and may not be inclusive of every data point an operator may track.


Header Section of the Daily Drilling Report

A daily drilling report includes a header section, which typically contains information about the location and status of the well. The header section also includes contact information for on-site personnel. Its purpose is to give the viewer the most pertinent information without looking through the details provided further down in the report.

Fields Found in the Daily Drilling Report

Report Date

Drilling Operations are typically tracked from 6am to 6am with two crews working 12-hour shifts each. The report date corresponds to the calendar date when reports are sent out at 6am.

Report Number

The number of reports that have been sent for the drilling project

Well Name

This can either be the legal well name that was filed on the drilling permit with the state regulatory agency or a common well name that is used within the organization. Operators can name their wells anything from the family name of the lease owners to their favorite superheroes. A typical format is “lease name_site number_well number_well type.” Example: Deborah 28 #1H

Job Name

WellEz On Demand references each phase of operating a well as a "job." An unconventional well can have a Drilling Job, Completion Job, and then possibly a Workover Job(s) as the well ages. Each job can be named after the phase, such as "Original Drilling," or can contain a brief description of the work being done such as "Utica: 27 Stage Slickwater Frac".


Operating companies typically do not own drilling rigs or employ full-time drilling crews. They “rent” or “lease” the specific type of drilling rig and crew needed for a job from a drilling contractor such as Halliburton or H&P.

Authorization for Expenditure # (AFE #)

An AFE is an approved budget for a job. Each AFE is assigned an internal identifier for tracking field costs in the company’s accounting systems. Most AFE numbers are a combination of letters and numbers containing the cost type (job type) and calendar year the project is occurring. Ex: HRZD201509


Area that has known hydrocarbons or other mineral resources


Area of surface land where a contract between the mineral owner and oil and gas company grants the company rights to explore, drill, and produce oil, gas, and other minerals for a specified term


Unique, permanent, numeric identifier assigned to each well drilled for oil and gas in the United States; the API number is one of many industry standards established by the American Petroleum Institute


Ground elevation above sea level at the well site; allows well log depths to be corrected to sea level

Rotary Kelly Bushing (RKB)

Height of the kelly bushing from ground level; depth measurements are commonly referenced to the kelly bushing instead of ground level

Spud Date

Generally, spud date refers to the date when the ground was first penetrated for the purposes of drilling an oil and gas well. However, some states vary in defining the terms at which a spud date can be identified.

Days from Spud (DFS)

Calendar days from the spud date of the well

Days on Location (DOL)

Calendar days from when the operating company first arrived on location; can include the time spent preparing the drill site and moving in the equipment needed to begin drilling operations

Measured Depth (MD)

Length of the wellbore as if determined by a measuring stick; calculated by measuring the lengths of all individual joints, collars, and other drill-string components and adding them together

True Vertical Depth (TVD)

Vertical distance from a point in the well to a point at the surface, usually the elevation of the RKB

24 Hr Footage

Difference in measured depth from the previous day at 6 a.m. to present day 6 a.m.

Hrs Drilling

Operators can define what constitutes drilling in different ways, but typically, it is the amount of time spent with the drill bit at the bottom of the wellbore

Present Operations

Short summary of what is happening at the time of reporting

Activity Planned

Short summary of what is planned for the coming day

Drilling Report Cost Summary

Drilling Report Cost Section of the Daily Drilling Report

Any time a cost is incurred during a drilling operation, it is coded to a specific accounting category or code that has been defined during the AFE process. These codes are then split into two groups: intangible and tangible codes. Intangible codes represent costs for equipment and services that have a subjective value and can vary depending on the circumstances. Tangible codes represent costs that are fixed and related to equipment or assets that will be permanently associated with the project. It is important to know that daily drilling reports typically contain only field estimates of costs happening at the well site.

The operating company does not know the true cost of the well until 60-90 days afterward, once all invoices have been submitted by various vendors and processed by the accounting department. Rig consultants/company men must code costs as accurately as possible so that the operations team can know if the project is going to exceed the budget (AFE) or not. In cases where the budget is exceeded, operations teams can write supplemental AFEs to increase the budget and properly allocate funds before final invoices are received and processed for the project.

Fields Found in the Daily Drilling Report

Drill AFE

Proposed total budget for the drilling project

Daily Intangible Drilling Cost (DIDC)

Daily total of field costs incurred under intangible accounting codes

Daily Tangible Drilling Cost (DTDC)

Daily total of field costs incurred under tangible accounting codes

Cumulative Daily Cost (CDC)

Sum of all field costs incurred on the well today

Cumulative Well Cost (CWC)

Sum of all field costs incurred on the well to date

Daily Mud Cost (DMC)

Daily total of field costs for drilling fluids, chemicals, and additives

Cumulative Mud Cost (CMC)

Cumulative total of field costs for drilling fluids, chemicals, and additives

Blowout Preventer (BOP)

Blowout Preventer Section of the Daily Drilling Report

The blowout preventer or BOP is a safety device installed on an oil and gas well to monitor and control pressure spikes during a kick or in the drilling process. Kicks in the pressure of the well can cause dangerous or even catastrophic failures known as a blowout. Blowout preventers activate various types of hydraulic rams that will close off the wellbore or shear the equipment downhole during a kick in pressure.

Fields Found in the Daily Drilling Report

Last BOP Test

Date the last time BOP pressure tests were conducted; BOP test intervals should be a maximum of every 21 days

Last BOP Drill

Date the last time a drill to simulate a kick in pressure was conducted by the drilling supervisor

Next BOP Test

Date of the next scheduled pressure test of the blowout preventer

Other Resources

Schlumberger Oilfield Glossary

Video of Large Deepwater Blowout Preventer (BOP)

Well Casing

Well Casing Section of the Daily Drilling Report

Casing is steel pipe lowered and cemented into place to stabilize a wellbore against collapses and increasing downhole pressures. Casing is placed to protect freshwater tables or isolate certain zones in the wellbore. Multiple strings of casing in smaller diameter are usually cemented into place during the drilling and completion process, adding multiple layers of protection.

Fields Found in the Daily Drilling Report

Casing Type

Used to differentiate the purpose of the casing; common names are:

Conductor Casing

Initial casing string to add stability; typically short and can be added before the drilling rig moves onsite; also referred to as conductor pipe or drive pipe

Surface Casing

Larger diameter pipe set to protect freshwater formations from contamination; blowout preventer or BOP is typically attached to the surface casing

Intermediate Casing

Protects wellbore stability against pressure abnormalities in the formation and potential wellbore collapses

Production Casing

Typically, this is the final casing string set to the TMD (total measured depth) of the wellbore across the reservoir. Production casing may be perforated during the completion process or have other completions components installed on it.


This is the outside diameter measurement of the casing. Sizes are standardized in the industry and displayed in inches, even in counties where the metric system is used in drill and complete operations.


Weight per foot of a casing string


This is the classification of the strength of the casing. Letter of the Grade refers to the tensile strength; the second part (number) refers to the minimum yield strength. Long strings of casing may require higher-grade materials on the upper portion to withstand the weight of the entire string.


Measured depth to which the casing is set, as measured along the wellbore


True vertical depth of the bottom of the casing, as measured from the kelly bushing

Other Resources

Schlumberger Oilfield Glossary

Video of Production Casing Installation

Drilling Mud Report

Driling Mud Section of the Daily Drilling Report

Drilling operations rely on the drilling fluids (mud) to do critical tasks like maintain hydrostatic pressure, transport the drill cuttings to the surface, cool the drill bit, and seal/preserve the wellbore. A daily drilling report often looks at the five basic properties of mud monitored or altered during the drilling process:

Fields Found in the Daily Drilling Report


Determines mud’s ability to suspend cuttings or clear obstructions to the surface

Mud Weight In (MWI)

Density of the drilling fluid as measured before entering the wellbore

Mud Weight Out (MWO)

An important comparison to mud weight in, mud weight out is the density of the drilling fluid as measured after exiting the wellbore.


Determines the flow properties of the mud

Funnel Viscosity (FV)

Basic measure of the viscosity profile of the mud observed in seconds per quart when poured through a Marsh funnel

Plastic Viscosity (PV)

Viscosity profile of the mud observed when measured by a rotating viscometer or rheometer

Yield Point (YP)

Minimum amount of shear stress required for the fluid to begin to flow

Gels (10S)

Gel strength measure reading from the dial on a rotating viscometer after 10 seconds of being undisturbed

Gels (10M)

Gel strength measure reading from the dial on a rotating viscometer after 10 minutes of being undisturbed

Gels (30M)

Gel strength measure reading from the dial on a rotating viscometer after 30 minutes of being undisturbed

Fluid Loss

Determines the loss of fluid to the formation and the maintenance of hydrostatic pressure

Filtrate Volume

Volume of mud filtrate measured after 30 minutes in API static filtration tests

Cake Thickness

Measurement of the thickness of the filter cake, usually recorded in 32nds of an inch

High-Pressure, High-Temperature Filtration Test (HTHP)

Measure of the static filtration behavior of mud at an elevated temperature and pressure

Water Loss (WL)

Volume of liquid measured in the filtration tests performed according to API specifications, in units of cm3/30 minutes

Chemical Properties

Monitoring mud’s chemical properties helps ensure that the mud’s physical properties are not changed or eroding the wellbore.


Indicates the mud system’s hydrogen ion concentration, determining acidity or alkalinity

Chlorides (Cl)

Indicates the total chlorides in the mud system

Potassium (K)

Indicates level in the mud system, promotes protective layer on wellbore wall

Calcium (Ca)

Indicates calcium level in mud system, promotes protective layer on wellbore wall

Phenolphthalein Alkalinity of Mud Filtrate (PF)

High point (8.3) of the alkalinity test, showing the concentration of OH, HCO, and CO3

Methyl Orange Alkalinity of Mud Filtrate (MF)

Low point (4.3) of the alkalinity test, showing the concentration of OH, HCO, and CO3

Methylene Blue Test (MBT)

Clay content in the system

Solids Control/Analysis

Low-Gravity Solids (LGS)

Measure of the part per billion of low-gravity solids like drill cuttings and bentonite

High-Gravity Solids (HGS)

Measure of the part per billion of high-gravity solids like barite and other mud additives

% Water

Measure of the volumetric proportion of water in the mud

% Oil

Measure of the volumetric proportion of oil in the mud

% Total Solids

Measure of the volumetric proportion of solids in the mud

Other Mud-Related Portions of the DDR

Mud Logging

The log of readings captured at the gas trap near the shakers in a mud system

Background Gas (BGG)

Average or baseline measure of gas entrained in circulating mud

Connection Gas (CG)

Influx of gas introduced into the drilling fluid when a pipe connection is made

Trip Gas (TG)

Gas entrained in the drilling fluid during a pipe trip, which typically results in a significant increase in gas that is circulated to the surface

Maximum Gas (MAX G)

Gas produced from the volume of cutting drilled

Formation Multi-Test (FMT)

Tool used to obtain pore pressure gradient to estimate production capabilities from parts of the log


The macroscopic nature of the mineral content, grain size, texture, and color of rocks

Mud Additives

Based on the indications of the five mud properties mentioned above, the mud engineer will perform calculations and determine the best mud additives to employ to optimize drilling and wellbore conditions.

Mud Product

Any product added to mud to perform a specific function, such as a weighting agent, viscosifer, or a lubricant


Measure of the additive product

Amt. Received

Cumulative amount of product received to date

Amt. Used

Cumulative amount of product used to date

Other Resources

Schlumberger Oilfield Glossary

Drill Bits

Drill Bit Section of the Daily Drilling Report

The drill bits section generally displays information about the current drill bit downhole as well as the last few that have been used. The information displayed includes identifying info, key performance indicators, and grading statistics for any bit pulled out of the hole.

Fields Found in the Daily Drilling Report

Number / Bit Number (No.)

The bit number signifies the order in which a specific drill bit is used during operations. Example: The third bit used on this job is bit number three. Bits can also be used multiple times through a job (see Re-Run) in which case the first bit number is still used, often noted with “RR.” Example: The first bit is run after the third bit but is shown on the report as bit “1RR”.

Bit Size / Bit OD / Bit Outside Diameter (Size)

The size of a drill bit is the diameter of the bit measured from the widest point of outside edge of the drill bit. Size is measured in inches unless otherwise indicated.

Manufacturer (MFG / MFR)

Company that manufactured the drill bit

Drill Bit Type (Type)

Drill bits are specifically designed for particular functions and drilling conditions and include many generic styles (PDC, Tricones, Drag Bits, Mill Bits, etc.). Further technical classifications are established by IADC Classifications and often included in a Type Description.

Serial Number (Ser No.)

Unique identifying number for a drill bit established by the manufacturer


Small-diameter tungsten carbide nozzles located on the face of the drill bit that produce a stream of high-velocity drilling fluid


A re-run occurs when a bit is used downhole, brought up to surface, and then placed back in the hole for another period of time.


Refers to the measured depth of the wellbore at the time the drill bit is put in the hole


Refers to the measured depth of the wellbore at the time the drill bit is taken out of the hole


Length drilled by a particular bit; also known as Progress

Hours on Bottom (HOB)

Hours spent with the drill bit on the bottom of the wellbore

Weight on Bit (WOB)

Amount of downward force exerted on the drill bit; normally measured in thousands of pounds

Revolutions Per Minute (RPM)

Number of full rotations the bit makes in a minute

Rate of Penetration (ROP)

Calculation of the Progress of the bit divided by the hours on bit; measured in feet per hour

Other Resources

Rig Zone Guide

Schlumberger Oilfield Glossary

Types of Drill Bits

IADC Dull Bit Grading

IADC Dull Bit Grading Section of the Daily Drilling Report

IADC bit dull grading was established in conjunction with SPE and used as a systematic method to communicate bit experiences and failures. The intent of the system is to accelerate product and operational development based on a uniform method for reporting.

Fields Found in the Daily Drilling Report

Dull Characteristics (Dull)

Observed characteristic most likely to limit further use of the bit

Location (Loc)

Location of the primary dull characteristic


Estimated wear on sealed bearings; linear scale from zero to eight


Reports and under-gauge condition for cutting elements intended to touch the wall of the wellbore


Remarks on other dull characteristics not listed above

Reason Pulled (RP)

Why the bit was pulled out of the hole; Ex: TD (total depth)

Other Resources

IADC Grading


Pumps Section of the Daily Drilling Report

Pumps are a common piece of equipment used during drilling operations in order to circulate fluids. They are essential for cooling the drill bit and flushing cuttings from the hole. The drilling or mud pump is designed to circulate the drilling fluid under high pressure down the drill string. There are several different types of pumps that can be used and different makes and models of each type of pump. The durability and longevity of pumps are crucial to a drilling job’s success. This makes the presence of pump data an important piece of the daily drilling report.

Fields Found in the Daily Drilling Report


Manufacturer of the pump


Type of pump (manufacturers often sell several different models)


Size of the liner, an interior piece of the pump

Stroke (STK)

Length of vertical movements (upward and downward)

Strokes Per Minute (SPM)

Number of strokes per minute

Pounds Per Square Inch (PSI)

Measures the pressure being exerted on the pump

Gallons Per Minute (GPM)

Gallons of fluid that are circulated by the pump per minute

Gallons Per Second (GPS)

Gallons of fluid that are circulated by the pump per second

Efficiency %

Relationship between the actual pump displacement and the ideal pump displacement; typically displayed as a percentage, such as 95% pump efficiency

Equivalent Circulating Density (ECD)

Effective density of the circulating fluid in the wellbore that results from the hydrostatic pressure imposed by the static fluid column and friction pressure (lb/gal)

Annular Velocity Drill Pipe (AV DP)

Measures the speed of the circulating fluid’s movement in the drill pipe

Annular Velocity Drill Collar (AV DC)

Measures the speed of the circulating fluid’s movement in the drill collar


Hydraulic horsepower of the bit which is a measurement of the energy per unit of time that is being expended across the bit nozzles


Hydraulic horsepower regarding the pump, which is a measurement of the energy per unit of time

Other Resources

Schlumberger Oilfield Glossary

IADC Glossary

Bottomhole Assembly (BHA)

Bottomhole Assembly Section of the Daily Drilling Report

BHA is the lower portion of the drill string, from the drill bit to the drill pipe. The BHA must provide force for the bit to break the rock (weight on bit), survive a hostile mechanical environment, and provide the driller with directional control of the well.

Fields Found in the Daily Drilling Report


Number of the individual BHA component; each item (component) that makes up the BHA is identified and numbered (#) in order from the bottom of the assembly to the top: #1 - bit, #2 - bit sub, #3 - mud motor, and so on.


Components is the list of identifying items that make up the BHA. The assembly can be simple or complex. Common components include a drill bit, bit sub, a mud motor (in certain cases), stabilizers, drill collar, heavy-weight drill pipe, jars, and crossovers for various thread forms. The selection of the right BHA components helps to ensure a high rate of penetration (ROP), quick and efficient drilling, and lower drilling cost.


The OD field is the Outer Diameter of each component in the BHA. It is important to know the OD of all components that go in the hole to calculate the annular volume between the BHA and wellbore for circulation and displacement volumes, to minimize tight spots in the wellbore, and in the event of a fishing job to recover lost or broken components from the hole.


The ID field is the Inner Diameter of each component in the BHA. Drilling fluid (mud) is pumped downhole through the BHA. The ID of all components that go into the hole is needed to calculate the circulation and displacement volumes. The component IDs will affect circulation-pumping pressures.


This field is the length of each individual component in the BHA. The BHA components are threaded together as they are run in the hole. Each component length is measured individually to know the total length of the BHA.


A BHA can be an assembly to perform specific operations. The BHA is given a description that indicates the purpose of the BHA such as Surface Drill, Drill Out, Curve Drill, and Lateral Assembly.


This is the total length of the BHA, the sum of all the individual component lengths. The length of the BHA will provide the desired weight on bit (WOB).

BHA Wt. Air

Weight of the BHA in the air without the effect of buoyancy provided by wellbore fluids or drag (friction) from contact with the wellbore

BHA Wt. Mud

This is the weight of the BHA adjusted for buoyancy when immersed in drilling fluid (Mud). As the BHA is immersed in mud, it becomes lighter. Changes in the density of the drilling fluid will affect the buoyancy of the BHA and the weight of the BHA in mud. Used for torque and drag models to assess hole problems

ROT. Wt.

This is the Rotating Weight or Free-Rotating Weight. The recorded weight of the drill string rotating off bottom, the pipe is not moving up or down, at the constant speed for a period of time; e.g., 80 RPM for 30 seconds. Rotating weight can be checked with pumps circulating drilling fluid or not, with pumps on or off. Used for torque and drag models to assess hole problems. The important point is to achieve a good clean baseline before the casing shoe is drilled, then friction factors can be adjusted for a clean well. This makes it easier to diagnose drilling problems.

P.U. Wt.

Pick-Up Weight is the surface weight measurement when pulling a pipe string out of the hole, moving up. Pick-up weight includes both string weight and frictional drag. It is used for torque and drag models to assess hole problems.

S.O. Wt.

Slack-Off Weight is the weight reading when the pipe is entering the well, moving down. It is compared to the pick-up weight to estimate the friction. The measurement is used for torque and drag models to assess hole problems.

Hrs. on Jars

Jars consisted of two interlocking links of pipe that can telescope. Drilling Jars are durable enough to withstand the harsh environment of drilling operations, but manufacturers have recommended change out intervals depending on the size of the jar and the operating conditions, bottom hole temperatures, straight or deviated hole, fishing time. There are two primary types, hydraulic (controlled hydraulic passages) and mechanical (series of springs, lock, and release). The two designs are quite different, but their operation is similar, energy is stored in the jar and can be suddenly released when fired. Jars can be designed to strike up, down, or both. Jars are used when the BHA is in a tight spot or stuck in the wellbore, and a jarring or hammering action is needed to work it free. In the case of striking up above a stuck BHA the upper link can be lifted, and when it reaches its firing point, the lower link is suddenly engaged.


Torque is the result of friction caused when rotating the drill string in the wellbore measure in foot-pounds, Kilogram-meters, joules, etc. This can be described as the force required to keep the drill string rotating. When drilling horizontal and extended reach wells, torque may become a problem. Too much torque on the BHA can damage components and can twist, buckle, or break pipe.

Other Resources

Schlumberger Oilfield Glossary – BHA

Schlumberger Oilfield Glossary – Jar

Deviation Survey

Deviation Section of the Daily Drilling Report

Also known as a directional survey, the survey provides a completed measurement of the wellbore’s departure from the vertical, typically at the total depth at the time of measurement. Survey measurements are taken at regular intervals in order to determine the present downhole location. The measurement and position of the well must be known with as much accuracy as possible to ensure the correct wellbore path. The measurements taken include inclination and azimuth, which are used to calculate other data points typically included in a survey report (which we have defined below). Measurement tools can range from simple devices attached to the drill string that measure the angle of the hole and are pulled out to inspect visually, to sophisticated tools such as MWD (measurement while drilling) that use electronic devices to take survey measurements continuously while drilling.

Fields Found in the Daily Drilling Report

Measured Depth (MD)

Total distance measured along the well path from the survey measurement to the surface reference point

True Vertical Depth (TVD)

Vertical distance from which the survey measurement is taken to a point at the surface


Deviation from vertical expressed in degrees


Angular measurement expressed in degrees, typically measured clockwise from north


Coordinates of the target north/south of the reference point


Coordinates of the target east/west of the reference point

Vertical Section

Horizontal distance or departure of a wellbore projected to a vertical plane of specific azimuth

Dog Leg Severity (DLS)

Normalized estimation of the overall curvature of the well path between two directional surveys

Other Resources

Schlumberger Oilfield Glossary

Wikipedia Article

Time Breakdown Section

Time Breakdown Section of the Daily Drilling Report

Time breakdown is a detailed account of operations during the previous 24 hours. Operations teams use this section to monitor activity at the well site, and coordinate equipment and personnel needed on site to assist in the drilling process.

Fields Found in the Daily Drilling Report


Before starting a drilling program, operators will define a set of activity codes used to identify the activity performed during a period of time. Codes allow engineers to analyze performance on a well by reviewing where the majority of time was spent during drilling operations. The IADC has a standard activity code list that most operators use with little variation. However, activity code lists are completely at the operator’s discretion.

Operations Comments

The rig supervisor or company man summarizes the well site activities and metrics during the specified time period in operations comments. This section of the report is heavily laden with industry shorthand and acronyms such as:


Move In Rotary Tool (the drilling rig and equipment)


Total Depth of well, also seen as RTD (rotary total depth) and LTD (log total depth)


Waiting on cement


Trip Out of Hole or POOH – Pulled Out of Hole (removing the drill from the wellbore)


Drill Stem Test (a procedure to test for the presence of hydrocarbons in the well)


Lost Circulation Material

Note: Shorthand and acronyms can vary from one crew to the next.


Conclusion Section of the Daily Drilling Report

Daily drilling reports are a vital part of any drilling operations team. Accurate and timely dissemination of the data contained in a DDR keeps operations on track and on budget. WellEz On Demand helps operators by ensuring quality data is collected from the field, organized, and distributed to all parties and stakeholders.

Additional Resources

Schlumberger Oilfield Glossary

IADC Drilling Lexicon & FAQ

OSHA Oil and Gas eTool