Computer Reservoir Continuity Study At Judy Creek
Authors: Delaney R.P. , Tsang P.B. 
Published: March 2010

A detailed reservoir study utilizing a computerized reservoir continuity analysis has been used in evaluating a depletion strategy for the Judy Creek Beaverhill Lake ‘A’ and ‘B’ pools of northern Alberta. The results of the study can be used In the analysis of the current production performance and other depletion strategies such as infill drilling and enhanced recovery.

The techniques used involved the use of the computer to measure statistically the degree of continuous reservoir in the highly stratified carbonates of the Judy Creek pools. All 200 wells In the Judy ‘A’ pool and the 70 in the Judy ‘B’ pool were used in this study. Reservoir continuity results were stored, together with geological correlative information, in a computer data base. By using the computer, these data and results can be displayed In areal and cross-sectional format and parameter interrelationships can be cross-plotted.

Results of the continuity analysis can help interpret and understand the results of various reservoir engineering analyses of past performance and future production strategies.

Introduction

Detailed reservoir description is an essential part of determining the depletion strategy for any reservoir, especially when it involves high-cost depletion schemes. These studies are most effective when the geologists and engineers work together as a team.

In such a reservoir study, the geologist usually supplies the reservoir engineer with a geological model. Ideally, such a model would be easily adjustable to match past production performance by changing the variable geological parameters or using alternative interpretations. The engineer can then simulate different depletion schemes with the chosen model. This will aid in the selection of an optimum depletion strategy.

Typically, geological data such as pay thickness, porosity, permeability, reservoir stratification and continuity are gathered from hand-drawn maps and cross sections which resulted from the geologist's interpretation of available data. This method is adequate in small pools where the number of wells is limited, and all the data can be handled manually without too much difficulty. In larger pools where there could be hundreds of wells, the task of correlating interpreted data across the entire pool becomes onerous. Given unlimited time and enough manpower, a good representative geological model can be built by manual interpretation. However, it is usually difficult to analyze and understand such a model because of the huge amount of information. Hence, conclusions are usually drawn from the use of only a few cross sections and maps that are considered to be typical of the entire pool. A better alternative is for the geologist first to transform the geological data into digital data and secondly transform his concepts and reservoir description technique into mathematical concepts and computer logic. This process allows all the available data to be included. The computerized geological data are also easily adjustable for various possible geological interpretations and may reduce the limitations inherent in oversimplified geological pictures.

This paper presents a case history of a reservoir study using a computerized geological model in the Judy Creek Beaverhill Lake ‘A’ and ‘B’ pools of northern Alberta.