tally, Oil & Gas Glossary

Tally refers to the running record of tubular goods on a drilling or workover rig, where each joint of drill pipe, tubing, or casing is individually measured, numbered, and tracked as it is run into or pulled out of the wellbore. A tally is the foundation of accurate depth control. Every joint length is recorded to the nearest 0.01 m (or 0.01 ft), and a cumulative running total tracks total measured depth (MD) of the string. A driller cannot know the true depth of the bit, the location of a packer, or the seating depth of a production tubing string without a reliable tally. In the WCSB, where long horizontal laterals in the Montney and Duvernay routinely exceed 5,000 m MD with lateral lengths over 3,000 m, a single mis-measured joint cascades into a depth error that places a frac sleeve in the wrong rock, lands a liner short of bottom, or sets a downhole tool meters away from its target. The strap log, the physical document that captures the tally, lists joint number, individual length, cumulative length, tool joint OD and ID, weight grade, premium connection type, and any inspection or torque-turn observations. Tallies are generated three times for every tubular: a yard tally before the pipe leaves the supplier, a rig-floor tally as joints are picked up onto the catwalk, and a running tally as each stand or single is made up and run. Each measurement is taken with a steel measuring tape, typically a 50 m or 100 ft survey tape, calibrated and free of stretch. Modern rigs increasingly use laser-based pipe measurement systems mounted on the V-door or the racking board, which feed directly into the electronic drilling recorder (EDR). Companies like SLB, Halliburton, and Pason supply EDR platforms that automate tally capture and reconcile rig measurements against directional surveys, BHA tool dimensions, and pipe inspection records. AER Directive 008 (measurement of well depths) requires that all reported total depths be traceable to a verified tally, and operators in Alberta must retain pipe tallies as part of the well file for the life of the well. Casing tallies determine final cement placement and centralizer spacing, tubing tallies dictate packer setting depth and nipple positioning, and drill pipe tallies underpin every directional survey calculation. A tally error of even 0.3 m on a 5,000 m string is enough to land a horizontal toe outside the target window in a 4 m thick Duvernay siltstone bench.

Key Takeaways

Joint-by-joint measurement record: A tally documents every tubular run into the well by individual joint number, with measured length to 0.01 m and cumulative running total tracked across the full string. Drill pipe tallies, casing tallies, and tubing tallies are kept as separate strap logs because each string serves a different depth-control function and must be reconciled independently against the directional survey and the cement bond log.
Three tally events per tubular: A yard tally is generated by the pipe supplier at the manufacturing or storage facility, a rig-floor tally is taken when joints are picked up off the catwalk, and a running tally is captured as each joint enters the hole. Discrepancies greater than 0.1 m per joint between the yard and rig tallies trigger remeasurement, since a steel tape stretches under load and over temperature swings common in Alberta winters.
AER Directive 008 traceability: Alberta operators must retain pipe tallies as permanent well-file records under AER Directive 008, which governs measurement of well depths. Reported TD on Form 11 well summaries, completion reports, and abandonment filings must reconcile against the physical tally. A discrepancy on audit is a non-compliance item and can require re-survey of the wellbore at operator cost, typically CAD 40,000 to CAD 120,000 for a wireline gyro run.
EDR integration and laser tally systems: Pason, SLB, and Halliburton EDR platforms automate tally capture by integrating laser pipe measurement, RFID joint tags, and barcoded thread protectors. A modern Montney horizontal rig running 7 inch intermediate casing captures over 280 joints in a single string, and electronic capture cuts tally errors from roughly 3 percent on manual tapes to under 0.2 percent, saving CAD 25,000 to CAD 80,000 per well in avoidable trip charges.
Direct economic stakes: A 0.3 m tally error on a 5,000 m Duvernay horizontal lands the toe outside the target 4 m siltstone bench, costing CAD 250,000 to CAD 600,000 in lost production over the well life. On casing strings, a tally error can result in centralizer placement that misses zones of weak rock, causing channeling and forcing a CAD 180,000 squeeze cement job during completion.

Strap Log Anatomy and Field Procedure

A strap log captures eight fields per joint: joint number, OD, weight (kg/m or lb/ft), grade (e.g., S-135, P-110, L-80), connection (premium or API), measured length, cumulative length, and remarks. On a typical Montney 7,000 m horizontal, drill pipe strap is recorded on 5 inch S-135 with NC50 connections, captured as 9 m doubles or 27 m triples depending on rig configuration. A floorhand measures each joint with a calibrated 50 m steel tape pulled taut across the catwalk, the driller cross-checks the value, and the company representative signs off. The strap log is kept in a bound book at the doghouse and uploaded daily to the EDR for the engineering team in Calgary, where it feeds the directional plot and the casing design model.

Casing and Tubing Tally Reconciliation

Casing tallies determine where the float collar, float shoe, and centralizers land in the open hole, which controls cement placement quality. A 4.5 inch 11.6 lb/ft P-110 production casing string for a Duvernay horizontal runs roughly 580 joints over 5,800 m, with centralizers placed every 12 m through the build and every 6 m across the lateral pay zone. Tubing tallies on a Montney gas well control packer setting depth, typically a Baker SAB-3 or Halliburton VRP set at 4,200 m KOP, plus or minus 0.5 m of nipple seating depth. A miss here means a wireline plug cannot land in the nipple profile and the operator pays for a redress trip at CAD 35,000 to CAD 70,000.

Fast Facts

The longest single-well drill pipe tally ever recorded in North America covered the 12,289 m Sakhalin-1 Z-44 extended-reach well in 2017, requiring over 1,360 joints of 5 inch drill pipe. The tally book filled three bound volumes. In the WCSB, the longest Montney horizontals push past 7,000 m MD with 4,500 m laterals, and rig crews now strap roughly 760 joints of drill pipe per well, a full 24 hours of cumulative measurement time per drilling phase if done with a hand tape, which is why laser-tally systems are now standard on top-tier rigs.

Tally directly informs Measured Depth, since cumulative joint length is the field measurement underpinning every reported MD value. The Drill Pipe string is the most-tallied tubular on any rig because it is constantly tripped in and out, while Casing tallies are static once cemented but become the permanent depth reference for all subsequent operations. The Kelly Bushing elevation is the zero datum against which all tally measurements are normalized, making KB-to-rotary-table dimension a critical input to every tally calculation.

Real-World WCSB Scenario: Duvernay Tally Audit at Fox Creek

A Calgary-based operator drilling a 5,650 m Duvernay horizontal near Fox Creek, Alberta in 2023 hit pay zone but completions logged the toe at 5,648.7 m, a 1.3 m short of the geological target in a 4 m thick siltstone bench. Post-mortem traced the discrepancy to a manual drill pipe tally where six joints in the build section had been recorded using an unverified 50 m tape that had stretched 0.05 percent under load. The cumulative error of 0.85 m, combined with a 0.5 m BHA dimensional error, placed the bit outside the target window. The operator paid CAD 285,000 for a wireline gyro re-survey and a sidetrack to recover the lost interval. AER Directive 008 documentation showed the tally book was not signed by the company representative on three of the six joints, a non-compliance item flagged in the next regulatory audit.

Following the incident, the operator standardized on Pason laser-pipe-measurement systems across its 14-rig fleet, mandated dual-witness signoff on every joint exceeding 9 m, and retrained 38 floorhands on calibrated tape procedures. Subsequent wells showed tally accuracy within 0.05 m over 5,000 m strings, eliminating recurring lost-target costs estimated at CAD 1.8 million per year across the program.