Abstract

Data from the Hambert-Aristocrat Field were used to demonstrate the integration of people and data from the disciplines of geology, geophysics, and petroleum engineering. This paper demonstrates how 3D seismic data can be coupled with log derived data, core analysis, and early production performance to identify areas of the field that may not be profitable (NPV <0 at 10%), and well locations that may be profitable (NPV>0 at 10%).

Bayesian techniques are used to calculate the maximum amount that can be paid for the integrated analysis of seismic data. The analysis takes into account the reliability of the information. In other words, given the evidence from the analysis indicates a location is profitable, what is the probability that the evidence is correct? Given the evidence from the analysis indicates a location is profitable, what is the probability that the evidence is incorrect? The reliability of the imperfect information is based on actual performance data from the Hambert-Aristocrat Field.

Sensitivity analysis is applied to establish an upper limit on information value, and establish the minimum reliability which makes the purchase of information cost effective.

Introduction

Operators have the opportunity to acquire many types of information; usually with the purpose improving profits by clarifying uncertainty. Several questions need to be addressed to answer this question. However a balance needs to be achieved between the cost of the information and the benefits derived from improved decision making. How much can we afford to pay to reduce uncertainty? When do the costs exceed the expected benefits? A method referred to as Bayesian analysis can be used to help answer these questions. The method was applied to the analysis of purchasing 3D seismic to resolve the uncertainty in reservoir quality and thus well selection (drill or don't drill). It is important to note that the seismic for the study area was not run with this objective. Current 3D seismic technology may have provided different conclusions than the analysis included in the following section. The following case study provides an example of the methodology to analyze the purchase of information to resolve uncertainty.

Case Study

The Hambert-Aristocrat Field in the Denver Julesburg Basin in Colorado was selected for the case study analysis. This case study was part of a larger Department of Energy Interdisciplinary Study of Reservoir Compartments and Heterogeneity conducted by the Colorado School of Mines. Figure 1 displays the study area and highlights the area contained within the seismic survey.

The Hambert-Aristocrat Field was discovered in 1972 and produces oil and gas from the Cretaceous Terry Sandstone along the east side of the Denver Basin. The Terry Sandstone in the study area produces from a depth of approximately 4500 feet. The reservoir has been interpreted as elongated, discrete, linear bodies deposited in a shoreface environment (Slatt, et al., DOE). Wrench faults in the Denver Basin have resulted in northeast trending faults with a secondary trend of northwest faults.

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