Geological analogs usage rates high in global survey

Six majors, nine international independents, two national oil companies, four US independents, and two independent exploration geologists were interviewed in six countries to gauge current practices and attitudes. Titles and job responsibilities spanned executives, managers, and professional staff. The survey respondents had varying experience in the industry (Fig. 1).

Analog data and information come from a variety of sources including data purchased from third parties, literature searches, databases, and consortia studies. Half the companies interviewed have purchased an analog database system, and five companies are building custom in-house digital analog systems (Fig. 2).

Nearly all E&P companies use analogs extensively. Analogs are widely used in both exploration and field development, but some companies indicate usage mostly in exploration or mostly in development (Fig. 3).

Other findings

Respondents also indicate:

1. Analogs are used in peer review meetings but are seldom part of look-back or post-mortem appraisals.
2. No one within the companies surveyed has codified analog best practices.
3. Analog use is about the same today as it was 20 years ago except more detailed data are available today, more probabilistic analysis is being done, and seismic is more often a deciding factor and the real driver in approving projects.
4. Analogs are often used in new ventures and international projects, but more people are starting to use them in mature basins for enhanced oil recovery techniques.
5. Analogs were mostly used by geologists in the past, but the recent trend indicates that reservoir engineers and petrophysicists are starting to use analogs to fill in the data gap, i.e., as "soft data."

Importance listed

E&P management and professional staff described the importance of geological analogs to exploration and field development in the following ways.

1. "Risk reduction from greater certainty on decisions—gives confidence to the geologist and reservoir engineer that their ideas are grounded in reality—shows them what is known versus unknown."
2. "Greatly enhances field development decisionmaking."
3. "Gives insight to the explorationist on the critical elements of a specific play that may be prospective."
4. "Uncovers subtle opportunities that may not be apparent from any other technique or technology."
5. "Improves predictive capabilities on the upside development potential."
6. "Convinces management, investors and partners of the commercial viability of a prospect or merits of a field development program."

Contrary views

There were significant contrary views that can best be understood from the following two verbatim comments from the interviews:

1. "Today, seismic technology sometimes becomes a ruling technology and that's too bad because sometimes analogs are put aside or not used the way they should be."
2. "Still today, some geologists only look at close-in data and completely miss the point of using analogs. Geologists should do more than look at what is close by."

Digital world

Many interviewees were also concerned about the "abuse" of the large amount of data in the digital world, citing the inability to validity-check or corroborate data, in particular when dealing with geological and reservoir information.

They also rated the quality of analogs more highly than the quantity of analogs, i.e., a reliable and thoroughly studied analog beats a large number of "case studies" that have lots of empty data points and provide incomplete analysis.

Improvement areas

Interview subjects made these recommendations to improve the art and science of applying geological analogs:

1. Best practices need to be documented and published.
2. A consortium should be established to fund the creation of a methodology for integrating seismic analog information with outcrop and subsurface geological data and engineering data.
3. More education is needed to convince more production geologists and reservoir engineers that decisions based on close-ology may not be optimum.

Searchable data

Analog databases with search engines are valuable resources that can help geologists lower exploration risk and help reservoir engineers make optimum development decisions.

In general, interviewees favor the use of a digital analog system for the following reasons:

1. Quick and efficient information finding supports decisionmaking.
2. Digital data are much easier to manipulate and analyze.
3. It is very easy to make global comparisons, i.e., higher quality analogs can be found by casting a global net across many fields and reservoirs.

The study also revealed that companies that have implemented digital analog database systems feel they benefit from online access to a catalog of basins and play types. Managers and users value these systems for the comprehensive data covered, including exploration history, structure, trap mechanism, depositional facies, reservoir architecture, rock and fluid properties, reserves estimates, development strategies, and production performance.

Acknowledgment

This independent research was conducted between Nov. 20, 2001, and Jan. 20, 2002, by Qittitut Consulting LLC on behalf of C&C Reservoirs. The aim of this study was twofold: first, to assess the real-world use and methodology of geological analogs in general and digital analog systems in particular; and second, determine the merits and effectiveness of the analog approach in exploration and field development.

C&C Reservoirs maintains a digital system that began as a worldwide carbonate fields database project at Chevron Overseas Petroleum Corp. in the 1990s and now contains data on nearly 1,000 clastic, fractured, and deepwater fields worldwide.

The authors

Dr. S. Qing Sun is director of geosciences with C&C Reservoirs. He was involved in Chevron Overseas Petroleum's giant carbonate field database project in 1994 and later that year co-founded C&C Reservoirs to expand the project into a multiclient program. He has a BS in petroleum geology from Daqing Petroleum Institute and PhD in geology from the University of Reading.

Dr. J.C. Wan ([email protected]) is director of technology development at C&C Reservoirs. He joined Shell Oil Co. in 1991 as a research physicist. For the next 6 years, he worked on the acoustic properties of unconsolidated sediments, AVO and amplitude interpretation, and seismic processing and migrations before joining Amerada Hess Corp. as manager of geophysical development. He joined C&C Reservoirs in 2001. He received a BS in physics from Nanjing University and a PhD in physics from the University of Minnesota.