Current Economic Appraisal Of Steam And Combustion Drives
Authors: Doscher Todd M. , Ershaghi Iraj 
Published: December 2007

Using an analytical derivation to account for the performance of a steam drive operation, and combining it with current economic operating and capital costs has led to the development of a compact program to estimate the discounted cost of steam driven oil.

An equally satisfactory analytical model for in-situ combustion not being available, the cost of producing oil by this process cannot be comparably generated. The assumption was therefore made that the heat that has to be developed in an in-situ combustion process is between 50% and 100% of the heat process is between 50% and 100% of the heat introduced into the reservoir as steam in order to duplicate the production performance of a steam drive. The discounted cost for producing oil by in-situ combustion was then producing oil by in-situ combustion was then found to be higher than for the comparable steam drive.

Although a greater net recovery of crude oil is theoretically possible for in-situ combustion, this factor may also be offset by using coal instead of lease crude for generating steam.

Introduction

Thermal recovery of crude oil is an established art in the petroleum industry. How is an art to be taught in a petroleum engineering department, particularly, in regard to transmitting an understanding of the reservoir processes that are involved and in imparting some insight into the predictability and profitability of such operations? predictability and profitability of such operations? Engineering after all is the applicability of science to earning a profit. And although profitability may at various times and in profitability may at various times and in various societies be measured by different yardsticks, in our society its measure is whether economic wealth has been increased.

An easy way is to approach the subject matter exclusively from a scientific viewpoint and make sure the student learns the appropriate differential forms of the heat transfer laws, and worry him with questions such as the precise measurement of the heat capacity of the reservoir rocks; but this is an abdication of responsibility. Such exercises properly belong and are included in basic courses in physics and thermodynamics.

Exposure to physical models of the processes — how they are defined, the processes — how they are defined, the results obtained from them, and then translation to prototype conditions is certainly one way of putting it all together. But, unfortunately, this is more than can be encompassed in a semester.

The use of a numerical simulator is another avenue of instruction, but a course centered on the use of a simulator becomes a course in operating the proverbial black box into which little insight can be gained by the novice. The simulator is a tool for the professional after significant mastering of fundamentals.

What is needed is a readily available analytical derivation of why the introduction of heat into the reservoir — as injected steam or burning oil — results in the production of oil. Then, the calculated effects production of oil. Then, the calculated effects of varying the governing parameters can be directly sensed by repeated exercises. Dollar values and discount rates can then be applied to the cost items and the production, and profitability estimated. This is what we attempted to do in developing a course in thermal recovery of crude oil.

AN ANALYTICAL DESCRIPTION OF THE STEAM DRIVE