Imagine the insight to be gained from showing every aspect of an already-drilled prospect, whether good or bad, to an audience of your peers for scrutiny.
We’re talking peers from a company other than your own.
There’s an industry forum that exists for this purpose.
It’s the DHI Interpretation and Risk Analysis Consortium.
The Consortium was formed in 2001 by Rose & Associates in Houston. The leadership team was comprised of R&A consultants (and AAPG members) Mike Forrest and Rocky Roden, with software support by Roger Holeywell.
“The three of us have been doing this now for almost 13 years,” Forrest said. “When (AAPG Honorary member) Pete Rose called me and asked me to manage this new group, none of us envisioned that it would last this long.”
Forrest provided a quick-look overview of the heart of the effort:
“The Consortium has built a seismic amplitude anomaly interpretation and risk analysis application referred to as SAAM (Seismic Amplitude Analysis Module),” he said. “The SAAM software is used to risk seismic amplitude anomalies from all AVO classes; it helps organizations better characterize the four AVO Class Gas Sand amplitude anomalies, often called DHIs.
“Over 230 prospects are currently in the software database for analysis,” he added, “and to help calibrate the weighting factors of the data quality and anomaly characteristics.”
He elaborated further on DHIs, emphasizing that seismic amplitude anomalies play a vital role in the prospect evaluation process.
“When these anomalies occur at a potential reservoir level, they are frequently called DHIs, or direct hydrocarbon indicators,” Forrest said. “They are changes in reflection response that may be related to oil and/or gas accumulations.”
He noted that DHIs include bright spots, flat spots, dim spots, character/phase change at a projected oil or gas/water contact, and an amplitude variation with offset.
A caveat: Seismic amplitude anomalies can be caused by factors other than commercial hydrocarbons, leading to incorrect interpretations. For example, a low porosity gas sand might be interpreted as a high porosity oil sand.
Some Good, Some Bad
Roden is an award-winning geologist, having won the 2011 Ziad Beydoun Memorial Award as co-author (with Stan Abele) of the best poster presented at the AAPG International Conference and Exhibition in Milan, Italy.
He delved into some of the consortium specifics.
“About a year or two into the consortium, we started a procedure where the different oil companies would show prospects, including everything they would if showing them to management or a potential partner,” he said. “This included well logs, seismic, technical analysis, everything.
“The prospects had been drilled,” Roden emphasized, “but they would get perspective from people who didn’t know the outcome, whether the well was good or bad.”
He noted the 230 wells now in the Consortium database are about evenly split between good and bad.
“There are all kinds of interesting trends and statistical things coming out of this,” he said. “All of the Consortium members have access to the database, which contains only the answers to questions we ask in our software.”
In other words, there’s no hard data, such as seismic lines, log interpretations and such.
A European section kicked off a few years ago after a number of international companies asked to join the group. There are regular meetings in Houston and Europe, and all members of one group also are members of the other.
Certain off-the-beaten-path venues can take on some added allure.
A recent meeting convened in Cape Town, South Africa, where Tullow Oil has a sizeable office. Tullow organized a field trip to the Karoo Basin in South Africa, which has world-class turbidite exposures.
“We had a full house,” Roden remarked.
Through the years, these get-togethers have yielded a raft of knowledge, triggering new ways to look at a wide variety of prospect ingredients in many instances.
“We recently found out that in prospects where the AVO interpretation is a large percent of the risk, you’re more apt to have a dry hole than if it’s not,” Roden said.
“What it relates to is, if all I have is an AVO interpretation and not anything else, and the AVO shows something hydrocarbon related, then I have a higher chance of a dry hole than a good one,” he noted. “This makes good sense in that if all you have is AVO response and nothing to calibrate to it, it quite usually is a wet sand.
“Next to a wet sand, low saturation gas is the second highest reason for failure,” Roden noted. “The third is no reservoir at all, and the fourth is a tight reservoir with low permeability and porosity.
“Half of the dry holes (in the database) that were wet sands are very thick wet sands,” Roden said. “They gave a seismic response misinterpreted to be a hydrocarbon response.”
The Consortium’s prospect presentation format is highly valued by the member companies.
“There’s not another forum in the industry where they can show prospects and get feedback from a bunch of peer companies who have different experiences, knowledge, approaches,” Roden emphasized.
“Internal feedback is good, but it’s not the only way to do something,” he noted. “People really like this.
“In fact, some companies send some of their new recruits,” he said. “This is a great way to learn.”