A hydrocarbon accounting system is a ten-year decision. Often longer. Your assets will outlive the contract, the project team, and possibly the vendor’s enthusiasm for the product. Yet most of these systems are bought on the strength of a demo that lasts an hour.

Demos are good at showing you features. They’re terrible at showing you year three: the regulatory change, the renegotiated agreement, the acquisition that doubles your well count overnight. That’s where the real cost of a hydrocarbon accounting system lives, and no demo will volunteer it.

So don’t evaluate the demo. Evaluate the answers. Here are the questions we’d put to every vendor in the room, along with what a good answer sounds like, and what should make you nervous.

Questions about change

“A regulation changes next quarter. Walk us through exactly what happens.”

This is the single most revealing question you can ask. You want names, steps, and timescales, not reassurance.

A good answer puts your own team at the centre. Your hydrocarbon accountant identifies the change, makes it, tests it, and can show an auditor precisely what changed and when. A warning sign is any answer involving a change request, a statement of work, or the phrase “our professional services team”. That’s not a process. That’s a queue, and your compliance deadline doesn’t care about queues.

“Show us a change one of your customers made without you.”

Vendors talk about flexibility. Evidence settles it. If customers genuinely control the system, examples will be easy to produce. If every example involves the vendor’s own consultants, you’ve learned who really holds the keys.

Questions about cost

“What did your existing customers pay for changes last year?”

The licence fee is the visible cost. The change costs are where budgets quietly die. Ask for real numbers: what a typical mid-contract modification costs, how long it takes, and how it’s priced. If changes are billed per statement of work, multiply by a decade of regulatory updates, new fields, and revised agreements before you compare prices. We’ve written more about this in before you sign: 3 questions every energy tech buyer should ask.

“What will upgrades cost us, in money and in downtime?”

Some systems require you to plan, test, and fund version migrations every few years. A true cloud platform does this continuously beneath you, with nothing for your team to schedule. The difference over ten years is enormous, and it never appears on the initial quote. Our Why PaaS page explains what to look for.

Questions about ownership

“If we build our allocation logic in your system, who owns it, and can we read it?”

There are two parts here, and both matter. Ownership on paper is common. Legibility is rarer. Your logic might be contractually yours, yet locked inside proprietary code that only the vendor can interpret. Insist on both: logic you own and logic your own people can open, read, and change. On EnergySys, that logic lives in Excel, which means the people who wrote it can always explain it.

“When an auditor asks how a number was produced, who answers?”

The right answer is: you do, on the spot, with the full chain visible from source data to final report. If the honest answer is “we raise it with the vendor”, then every audit becomes a dependency, and trust in your reporting rests on someone else’s responsiveness.

Questions about resilience

“Tell us about a customer who went through a merger or divestment on your system.”

Acquisitions and divestments are where hydrocarbon accounting systems break, because ownership structures, agreements, and asset lists all change at once. Ask for a real example with real timescales. For reference: Santos replaced a legacy system across all operated assets in under ten months, and BPX Energy absorbed a $10.5bn acquisition on the platform. Whatever system you choose, it should have stories like these, and the vendor should be keen to tell them.

“What happens to us if your product strategy changes?”

Vendors get acquired. Products get sunset. Roadmaps get “consolidated”. Ask how much of your operation would be exposed if the product’s direction changed, and listen for whether your logic and data would move with you.

Questions about leaving

“How do we exit, and what does it cost?”

Ask this early, in front of everyone, and watch the room. It’s the question that reveals the most about the relationship you’re entering. If your data exports cleanly and your logic is readable outside the system, the vendor has to keep earning your renewal. If leaving means a migration project priced by the people you’re leaving, you’re not buying software. You’re buying a very comfortable trap.

A confident vendor answers this one without flinching. That confidence tells you more than any feature list.

One question to ask yourselves

“Who in our team should control this system?”

Before any vendor conversation, settle this internally. If the answer is your own hydrocarbon accountants and production engineers, the people who understand the agreements and live with the month-end, then you’re not really shopping for features. You’re shopping for a platform they can build on, and a partner whose domain expertise fits your operation. That changes which answers above matter most, and it’s the question we’d start with. Our guide to choosing hydrocarbon accounting software covers this decision in full.

Bring us your hardest question

We’re happy to sit on the receiving end of every question in this piece. EnergySys has hosted hydrocarbon accounting workloads for over 25 years; the logic our customers build is theirs and readable, and our partner model means one contract, specialist support, and no lock-in.

Book a call, bring the list, and we’ll answer it straight. If the platform model fits, we’ll match you with the right partner. If it doesn’t, we’ll tell you that too.