Reserves and Well Economics Software: Custom Build vs Off the Shelf

What ARIES, PHDWin and Val Nav actually do well

Start with the part nobody disputes. The decline curve arithmetic in Halliburton ARIES and in PHDWin is correct, it has been correct for decades, and your reserve auditor recognises the output on sight. When Netherland Sewell, Ryder Scott or Cawley Gillespie open a case from either engine, nobody is checking whether the exponential is exponential. Acceptance by a third party is a feature you cannot build, and it is the strongest single argument for staying on a licensed tool.

PHDWin is quick to work in, and one evaluator can carry a few hundred wells in it without ceremony. ARIES carries the conventions that lenders and auditors expect to see. Quorum Aucerna Val Nav genuinely does handle corporate roll up, case management and an approval chain, and for a large operator willing to run an enterprise implementation it is the honest buy answer to most of what follows here. Enverus PRISM is excellent at type curve benchmarking and offset performance, and it belongs alongside whatever you run internally rather than being replaced by it.

So say the plain thing early. Most operators reading a build vs buy comparison for reserves and well economics software should buy. If you run a few hundred wells with one evaluator, one lender and no public filing, PHDWin plus a naming convention your team actually follows is adequate, and a custom build competes with drilling capital for no return. We say that on first calls and it costs us work.

Where off the shelf reserves software stops

The gap is not in the mathematics. It is in the system of record wrapped around the model.

Here is the workflow that generic products model badly. In September you run a bank case at the lender's price deck for a borrowing base redetermination. In December you run the year end case at the prescribed basis, which is an unweighted twelve month average of first day of month prices rather than anybody's forecast. In February the report supports a public disclosure and possibly an impairment test. In April somebody asks why the operating cost assumption on one package moved from $4.80 to $6.20 between those two cases.

In file based practice, the September case is a database copy on a shared drive named with the evaluator's initials. The year end case is a different copy. Between them sat a spreadsheet of revised field costs from accounting, an email about a workover programme, and one evening where somebody went through and tidied up. The delta exists. The reason does not, and no product on the market reconstructs it, because these products version files rather than assumptions.

Two consequences follow, and both cost money. The year over year reconciliation into revisions of previous estimates, extensions and discoveries, improved recovery, purchases and sales of reserves in place, and production gets assembled by hand each January by somebody comparing two databases and exercising judgement about which bucket a change belongs in. And the proved undeveloped inventory, which under SEC rules generally has to be scheduled for development within five years of first booking, sits against a nominal date that slips every year rather than against the capital budget your board actually approved.

The arithmetic: per seat licensing versus the cost to build

Do this with your own renewal invoice rather than with anybody's list price. Take the annual figure across evaluation seats, maintenance and any enterprise module, then divide by the number of people who open the software in a normal month. Operators are usually surprised twice: by how high the per seat figure gets once maintenance is included, and by how few people it divides across.

Then build the second column, which never appears on an invoice. Count the hours your evaluator, your reserves accountant and your financial reporting lead spend in January reconstructing the reconciliation, answering the auditor's open item list, and rebuilding cases that already exist somewhere on a shared drive. Cost those hours at fully loaded rates. In the operators we have worked with, that second column is the larger one.

Now the crossover. As a working rule, licensed evaluation tools stay cheaper than a build until you pass roughly twelve to fifteen active evaluation seats, or until a single corporate roll up crosses about four thousand wells across four concurrent cases. Below either line, buy and stop reading. Above both, the licence is no longer the expensive part of the year. The expensive part is those two weeks in January and the audit cycle behind them, and that cost scales with well count while the licence scales with headcount. The divergence between those two curves is the entire decision.

Add one more figure before you compare. If a redetermination slips because your cases will not reconcile, price the delay. Your treasurer can already tell you what a month of a smaller borrowing base costs.

What a custom build actually costs

From Digital Heroes delivery experience on audit sensitive financial modelling systems, a first release covering case management, versioned and effective dated assumptions, an approval workflow, a classified change log and a corporate roll up that reconciles at every level runs $80,000 to $160,000 across 14 to 20 weeks. A full evaluation platform adding development scheduling, multi case comparison, hedge overlays, acquisition and divestiture handling and a validated economics engine runs $200,000 to $450,000 phased over 6 to 12 months.

Two lines are missing from nearly every quote you will be handed. Data migration adds 10 to 25 percent of the build on top of the build, and reserves sits at the upper end of that band, because loading prior years in a form that genuinely reproduces approved cases is a different exercise from copying a well list across. Then year two. Budget 15 to 20 percent of build cost annually for support, price deck season changes, and the enhancement work that arrives once evaluators start using the change log instead of working around it.

The largest scope decision is whether you rebuild the economics engine or wrap the one you already run. Wrap it. Not because the arithmetic is difficult, it is deterministic, but because a home grown engine has to be validated well by well against the incumbent before an auditor or a lender will accept its output, and that validation project buys your evaluators nothing they asked for.

The four situations where building wins

Custom versus off the shelf turns on four conditions. One alone rarely justifies the spend. Two together almost always do.

• Regulatory fit. You file publicly, so the reconciliation categories, the pricing basis and the five year rule on proved undeveloped locations are disclosure obligations with an auditor attached rather than internal preferences. When the product cannot record a classification at the moment of the edit, you rebuild the disclosure every January from evidence that has already gone cold.
• Scale economics. Past roughly four thousand wells with concurrent lender, disclosure, strip and asset team cases, the roll up is a computation problem rather than a spreadsheet, and per seat pricing stops being the number that decides anything.
• A workflow that is your competitive advantage. If your business is acquiring packages and repricing them faster than a seller can respond, ownership handling with effective dates and same day case rebuilds is the capability you are actually selling. That does not belong on another vendor's release schedule.
• Integration sprawl across three or more systems. Actual volumes from production accounting, actual operating cost from the ledger, the drilling schedule from planning, ownership from the land system, hedges from treasury. Once four of those have to agree with the reserve database every month, the integration layer is the project and the evaluation tool is one component inside it.

How to decide in a week

Run this test instead of booking three more demonstrations.

Monday, pull your September bank case and your December year end case. Tuesday, ask your evaluator for a list of every assumption that differs between them with the reason and date of each change, and give them the whole day for it. Wednesday, take that list to your reserves accountant and ask which entries they could defend to an auditor without making a phone call. Thursday, put both cases in front of whoever owns the lender relationship and ask whether they could answer a redetermination question from what you now hold. Friday, total the hours the exercise consumed and multiply by four, because that is your January.

If the list came back complete on Tuesday afternoon, renew your licences and spend the money on wells. If it took three people and still had gaps, you have measured your build case in your own numbers rather than in a vendor's.

The next step is a paid discovery phase, not a proposal deck. At Digital Heroes that means a signed product requirements document covering the assumption model, the approval chain, the reconciliation categories and the acceptance criteria, written before any code exists, with the named engineers who would do the work in the room while it is written. You keep the specification whether or not you build with us, and it is what allows a fixed quote to hold. Contracting runs through our India LLP, US LLC or UK LTD entity so the intellectual property assigns under your own law.

We are the wrong firm if you want a reserve auditor's opinion, a petroleum engineering staffing body, or a developer willing to reimplement decline curve arithmetic because integrating looked harder. More than fifty specialists and over 2,000 delivered projects, verifiable on Clutch, Trustpilot, Fiverr Vetted Pro and our D-U-N-S record, still does not make us the right answer if your real problem is that PHDWin is unfamiliar to a new hire.

Book a 30-minute call with Digital Heroes and get a written plan and a fixed quote within 48 hours.