Methodology
How we classify wells and build production numbers. Last updated: 22 July 2026.
Four geographies, kept honest
Every well carries up to four geographic labels, each with a precise meaning:
- Supply Region — the coarse, trader-recognizable producing region (Permian, Appalachia, Eagle Ford, …). County-based and total: every well belongs to exactly one. This is the macro rollup for supply views.
- Basin — the strict geologic province (Permian Basin, Appalachian Basin). Narrower than the market’s loose usage of “basin”, deliberately.
- Sub-basin — the geologic subdivision (Midland, Delaware, …).
- Play — the producing interval × commercial extent (Barnett Shale, Eagle Ford Shale). Assigned only on rock evidence — see below — so it is honestly sparse: wells without formation evidence show “Unassigned — no formation evidence”, never a guess.
Play assignment: rock-evidenced only — and why we don’t infer
A well gets a play label only when regulator-reported formation evidence places it in the play’s producing interval within the play’s extent. We do not fill the gaps with location-based inference, and we tested that choice rather than assuming it.
In July 2026 we calibrated a polygon-scoped inference gate — footprint scope × well profile (horizontal, vintage, fluid) × a kriged formation-depth window — against a masked holdout of rock-evidenced wells. The best achievable precision was 92.8% (Barnett), 94.1% (Haynesville — Texas side of the fairway only: Louisiana lacks the depth surfaces the test depends on, so we did not test it there), and 91.7% (Eagle Ford) — below our ≥95% publication bar, and reached while correctly labelling only 11–22% of the candidate wells (20–77 per play). The failure is structural, not a tuning miss: after the profile gates, the remaining candidates sit in rock that is vertically contiguous with the play (Marble Falls directly on the Barnett; Austin Chalk within ~13 ft of the Eagle Ford top; basal Cotton Valley on the Bossier). Contact offsets of 0–300 ft cannot be adjudicated by depth surfaces whose honest uncertainty is 174–529 ft — the discriminand is smaller than the ruler. (The calibration scope is separate from page coverage: our Haynesville play pages cover the full Texas–Louisiana–Arkansas footprint; only this inference test was Texas-scoped.)
The recoverable pool is also small: 86–99% of formation-null wells in these footprints are pre-play conventional verticals that fail the profile gates honestly; a bar-clearing gate would add only dozens of wells (+0.1–0.3% of the page cohorts). So instead of inferred labels, our play pages publish two numbers side by side: the rock-evidenced well count and the total footprint count. You always see both.
Footprint definitions
- DPR county lists. Supply-region footprints for the major plays follow the EIA Drilling Productivity Report RegionCounties list (dpr-data.xlsx, fetched 12 July 2026; 315 counties across 7 regions). The DPR itself is discontinued — final release 13 May 2024 — but the EIA still serves the file and it still parses to exactly that county set, so our map is reproducible, just frozen at that vintage. The current STEO breaks out only five regions plus “Rest of Lower 48”, folding Niobrara and Anadarko into the residual — our 7-region set is a deliberate superset of current EIA practice, not a mirror of it (we have located no published county crosswalk for the 5-region set).
- Barnett is our own definition — it is not a DPR region. We define a 27-county footprint: the 9 core Barnett Shale counties (Tarrant, Johnson, Wise, Denton, Parker, Hood, Somervell, Ellis, Hill) plus 18 surrounding Fort Worth Basin / Bend Arch producing counties. It deliberately excludes the Central and South Texas counties that over-broad “North Central Texas” province labels sweep in.
- Anadarko vs Mid-Continent. The DPR county list decides: a well in a DPR Anadarko county is Anadarko; a well whose geology says Anadarko Basin but whose county is outside the DPR list is Mid-Continent. Our “Mid-Continent” is the non-DPR conventional remainder of the Kansas/Oklahoma shelf — it does not contain Anadarko.
Production numbers: best estimate, revised honestly
- Production series are our best estimate: regulator-reported volumes plus reliably inferred rows — lease-to-well allocation (Texas), gap-fill, and reconciliation — each tagged with its origin. Where a source is unrecoverably corrupt and no reliable estimate exists, we omit rather than fabricate.
- Figures labeled best estimate include those inferred rows; figures labeled reported are regulator-reported only.
- Recent periods revise upward as late filings arrive — a structural feature of regulatory reporting, not an error. Annual figures for the latest year settle over several months.
- EIA reconciliation. We reconcile our production series against EIA figures across most U.S. producing states and track the difference over time. Some U.S. series — including Alabama and the federal offshore — are not yet tied out, and the EIA publishes no comparable figure for our Canadian and international regions. The per-region reconciliation detail is being prepared for publication.
- Footprint production aggregates cover all wells in the county footprint, not only rock-evidenced play wells — the same two-number honesty as the well counts.
See it applied
The play pages put this methodology to work: Barnett Shale, Eagle Ford Shale, Haynesville Shale.
Questions about a specific number? [email protected] — every figure we publish is traceable to its sources.