New Methods for Controlled Injection of Steam Into Multiple Sands

ABSTRACT Chevron has been employing two new completion methods to control steam injection into multiple oil-bearing horizons using a single injection well. The two methods, parallel tubing injection and limited entry injection, are used to improve steam utilization and to reduce the need to drill new injection wells. One of the methods used previously was concentric injection in which steam is injected down two concentric pipes placed inside the wellbore and thereby distributed to two separate sands. The outer pipe can be the well casing itself. This method, however, proved unsatisfactory because one of the strings became plugged due to scale buildup. As a result, injection into both sands was no longer possible. For this reason, the concentric injection method is no longer used. Instead, parallel tubing injection and limited entry injection methods are currently used. This paper reviews the concentric injection method and presents conceptual details of the two new methods. Theoretical calculations supporting application of these methods are also presented.