depth severance source comparison: Start with the clause as recorded
A depth comparison can go wrong before any numbers reach a spreadsheet. The error often begins when a researcher shortens a clause to a formation name or a depth value and drops the language that explains what the reference means. The working table should therefore begin with a verbatim excerpt, its instrument number, the document's role in the chain, and an exact page or image locator.
Read beyond the sentence containing the depth reference. Definitions may establish whether a named horizon means the top, base, or another marker. A granting clause and a reservation can use similar words for opposite purposes. An exhibit may be incorporated into the instrument, merely attached for convenience, or referenced without appearing in the recorded images. The comparison needs enough context for a reviewer to see which of those conditions applies.
Record execution and recording dates in separate columns. Neither date tells the researcher, without more text, when a severance became effective or whether a later instrument changed it. Amendments, releases, assignments, and ratifications belong in the source sequence even if only one of them contains the wording under review. The table is a map of the evidence, not a substitute for reading the chain.
A formation description may depend on a named geologic unit and a stated position within it. A numeric description may depend on a reference well, an elevation datum, and a measurement convention. Copying both into a column labeled "depth" makes them look directly comparable when the instruments may be answering different questions.
Keep the publisher's language. If an instrument says "below the base" of a formation, do not reduce it to the formation name alone. If it gives 8,000 feet, preserve any accompanying phrase that identifies the well, surface location, elevation, measured depth, true vertical depth, subsea datum, or other reference. A blank measurement label must remain blank. The absence of a label is an exception, not permission to choose the convention that makes the numbers line up.
Spelling and naming variations deserve the same restraint. One source may use an older formation name, an operator's informal label, or a combined interval. Another may use a regulator or service-company label. Normalized search terms can help locate records, but the comparison should retain each source string and show who approved any correlation between them.
The reference well has to be identified, not guessed
A clause tied to a well needs the complete identifier available in the instrument. Record the well name and number exactly as shown, along with any API number, lease name, survey description, or exhibit marker that helps distinguish it. Similar well names in the same field do not establish that a log or directional survey belongs to the referenced well.
Once the well is identified, inventory the materials actually available for it. The recorded instrument may include a log image, a marked formation pick, or a small diagram. A regulator query may lead to completion or directional records. Internal technical material may also exist. Each source has a role, date, and version. A database value observed later should not be presented as if it appeared in the conveyance.
Retrieval notes should be precise when a record is missing. Save the jurisdiction searched, query route, identifiers used, date of access, and result. "No log found" is too broad if the search covered only one online index. The useful statement is that a named query returned no matching item, followed by the next custodian or identifier to check.
Measurement basis changes the comparison
Measured depth follows the wellbore. True vertical depth expresses vertical distance from a stated reference. Those values can separate materially in a directional hole. Reference elevations and subsea conventions can add another difference. When an instrument supplies a number without naming the basis, an analyst cannot repair the omission by consulting a modern well display and assuming its convention applies backward.
Create distinct fields for the quoted value, unit, measurement label, reference elevation or datum, reference well, and source page. If a reviewer later provides a conversion, store the result in a separate reviewed-observation section. Include the source logs or surveys used, their versions, the method described by the reviewer, the date, and the assets for which the result was approved.
Never replace the recorded value with the converted one. Future work may use a different log revision or formation pick, and the team must be able to reproduce both the original clause and the reviewed analysis. Keeping the two apart also prevents a technical conclusion prepared for one well from migrating to another asset because the wells share a field or operator name.
A side-by-side example exposes the unresolved question
Assume a lease reserves rights below the base of a named formation. A later assignment describes rights below 8,000 feet in a reference well, but the text does not say whether 8,000 means measured depth or true vertical depth. The two clauses belong on separate rows. Quote each one, identify its document role, and list every stated reference.
The exception is not "depth mismatch." That phrase hides the work. The exception should say that one boundary uses a formation marker while the other uses an unlabeled numeric depth, and that the available record does not establish the measurement convention or correlation. The requested decision can then be narrow: which technical or legal reviewer will determine whether a comparison is supportable, and what additional evidence does that reviewer require?
Do not draw a common horizontal line on a map merely because the clauses appear in the same ownership chain. A neat graphic can overstate certainty more effectively than a bad sentence. Any illustration should distinguish quoted terms, source-derived locations, and reviewed interpretation. It should also show unresolved references instead of smoothing them away.
Review the chain before sending the question
Before handoff, reopen every operative paragraph and its definitions. Confirm that cited exhibits are present and that the instrument actually incorporates them. Check the grant or reservation role, instrument number, parties, dates, land description, page, and any reference-well identifier. Then trace amendments and releases far enough to show whether the quoted language was later addressed.
A second researcher should repeat the critical retrievals from the saved locators. That review catches clipped clauses, transposed numbers, mismatched wells, and assumptions introduced during normalization. It should also confirm that formation and numeric references remain in their original categories throughout the table.
The final packet includes the instrument sequence, verbatim clauses, page images where permitted, reference-well index, measurement fields, source diagrams, search history, and open questions. If a specialist supplied a correlation, include the inputs and approval trail without rewriting the source-text columns. Close an exception only when the required evidence and the named review decision are both present.
This source comparison organizes recorded language and technical references for review. It does not decide title, correlate formations, locate a boundary, or interpret the instruments. Those limitations belong beside the table so that a convenient comparison does not become an unsupported conclusion.
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Authoritative starting points
Use the official custodian relevant to the asset and jurisdiction. These sources help confirm terminology, record coverage, identifiers, and access routes:
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