The use of geological analogs has been a common practice among geoscientists. The analogs are used by geoscientists and engineers in solving challenging exploration, development and production problems. Effectively using analogs as an integral part of the exploration and production (E&P) workflow will help reduce exploration and development risks.
At C&C Reservoirs we have realized the needs of the E&P industry and have developed a global analogs system, namely Digital Analogs Knowledge System (DAKS). The system captures and analyzes data and information on more than a thousand of the world's most important reservoirs (Figure 1). It presents a re-interpretation, verification and synthesis of available data using modern concepts and techniques achieved through rigorous analysis and standardization processes. The system has been widely adopted by the E&P industry since its inception.

A K-I-D-based global analog system
In the information age, we are overwhelmed with "data" or "databases." However, in reality our decisions cannot be made on the basis of data alone. It is the knowledge or understanding of the data that determines what decisions one should make in E&P endeavors (Figure 2). In the process of building global field and reservoir analogs, we have applied the concept of the Knowledge-Information-Data (K-I-D) system. A K-I-D-based analogs system must follow the principles of data entropy, document and database integration, and context integration. The following steps outline the life cycle of design, implementation and update of DAKS:
• Define business processes/decision points in the E&P workflow;
• Identify and classify knowledge, information and data needed at each decision point;
• Establish a K-I-D model for the analogs;
• Populate and maintain the K-I-D model;
• Store, retrieve and interact with the K-I-D of analogs through an intuitive graphical user interface (GUI);
• Deliver the K-I-D of analogs through the Internet/intranet; and
• Apply the K-I-D of analogs in decision-making processes and update K-I-D with additional analogs and new information.
A K-I-D item in DAKS contains the following elements:
• Data. Observations and measurements reconciled from various data sources. For example, the relational database at the reservoir level consists of more than 170 parameters covering general, trap, reservoir, source, seal, reserves, production, hydrocarbon composition, engineering and recovery.
• Information. Data plus relevance and purpose described in a comprehensive report. For example, each of the reservoir evaluation reports cover exploration history, basin evolution and petroleum systems, structural features, trapping mechanisms, stratigraphy, depositional facies, reservoir architecture, rock and fluid properties, development strategies, recovery mechanism, reservoir management, and improved recovery techniques.
• Knowledge. Information plus application and use (associated with action) in the form of well classified and analyzed analog data with lessons learned and applications in E&P workflow. For example, each E&P Synthesis and Treatise report categorizes and analyzes the world's giant fields according to play type, reservoir and fluid characteristics, recovery mechanisms, and various engineering attributes with a view to gain a better understanding of the key geologic and engineering factors that contribute to exploration success and control reservoir performance and recovery efficiency.
• K-I-D Platform. Internet/intranet application with an intuitive GUI and powerful multi-criteria and global information systems (GIS) search engines to allow the access of the right analogs by users whenever and wherever needed in the world. The analog K-I-D items can be analyzed online or downloaded to the user's computer for analysis at the click of a mouse. Users in every segment of the E&P workflow can easily evaluate the exploration and development challenges and opportunities with a global perspective.

Application of a global analog system
Nearly all E&P decision-makers use field and reservoir analogs extensively. However, many E&P teams follow an informal and inefficient process that spans only the knowledge gained from the team's own geological and geophysical experience. With DAKS geoscientists and reservoir engineers have a way to improve operational efficiency and reduce their E&P risks. The system provides a worldwide set of objective information available for each of the decision-making processes in the E&P workflow. By escaping the limits of their direct experience, the E&P teams can generate new exploration ideas and test them against a worldwide set of more than a thousand reservoirs. DAKS can aid in evaluating appraisal plans and optimizing development options for newly discovered reservoirs and in assessing the effectiveness of alternative recovery techniques in production enhancement. In addition, the system can also help benchmark reservoir performance potential against analogous mature and declining fields.
By clarifying the known against the unknown based on a large body of knowledge, geoscientists and engineers can have greater confidence in their assessment of field and reservoir potential. E&P teams have access to the knowledge that they need to help convince management, investors and partners of key decisions such as the commercial viability or significant risk of a prospect or field development program. Key applications include:
Exploration. Subsurface geological analogs provide a simple yet powerful and cost-effective technique for generating new exploration ideas and reducing uncertainties in frontier basins where data is scarce or unavailable. By establishing the critical elements of the known plays both within and outside the basin of interest, the explorationists can develop the critical elements of a similar play in an unknown area, which in turn leads to discovery. This approach generally begins with a search for analogs based on general geological factors such as basin type or trap style but may be adjusted to specific queries in the exploration strategy. Then the key elements of the analog subset are reviewed and compared, and individual analogs are studied in detail. The results may be used to establish risk factors in the absence of other information.
In areas where ideas have been exhausted, DAKS can be used to search for prospects and play ideas that have not been tested. The application of successful play analogs can guide explorationists in revitalizing old areas by applying new thinking. Mature basins may contain horizons previously ignored because of high exploration risks or prohibitive costs. Through the use of this system, a quick comparison with analogs in similar geologic settings can help convert these bypassed zones into exploration opportunities.
Field Development. Field analogs are an essential component for a successful field development plan after appraisal and for monitoring and benchmarking at any stage in the production history of the reservoir. In the absence of complete information of reservoir and fluid properties, it is often necessary to compare with successfully developed reservoirs in similar subsurface settings. Further analysis of analog information provides knowledge and insight into the key geologic and engineering factors that control reservoir performance and recovery efficiency. More importantly, subsurface analogs are the only reliable source of lessons learned and therefore provide a "reality check" before embarking on major development programs.
During the process of field development planning, there are many uncertainties regarding the potential performance of a field, particularly in the early stages where few wells have been drilled due to high drilling costs (for example, in the deepwater environment). Various scenarios produced by reservoir simulation provide concepts on which these uncertainties can be reduced. An alternative and supporting approach is to compare analog fields having similar reservoir and fluid types, pressure, water depth, drive mechanism and other technological challenges. Critical field/reservoir analogs provide not only ideas but also quantitative analysis to help in development planning and production optimization. This can help E&P companies reduce the risks of over- or underestimating production rates and recoverable reserves. Many potential production problems can also be recognized early in the development phase through the use of analogs, thus allowing for appropriate data gathering and mitigation scenarios to be planned for and initiated.
Production Enhancement. Improving hydrocarbon recovery is a global challenge for today's E&P companies. A key element in this endeavor is the improvement of recovery factors through the correct choice of enhanced oil recovery techniques. DAKS can help managers and engineers refine their choice of secondary or tertiary recovery methods by quickly finding the most appropriate reservoir management or production enhancement strategy for their field of interest. A typical application in production enhancement consists of finding all fields that share a similar set of geological and engineering parameters and that have gone through secondary and tertiary recovery production stages. The performance of production enhancement cases can be readily retrieved and reviewed. With lessons learned from these analog fields, engineers can quickly discover the most effective production enhancement methods and estimated performance for their candidate fields.

For more information, please visit www.ccreservoirs.com.