Attacking Those Troublesome Dual Gas Lift Installations
Authors: Davis Jerry B. , Brown Kermit E. 
Published: December 2007

This paper was prepared for presentation at the 47th Annual Fall Meeting of the Society of Petroleum Engineers held in San Antonio, Tex., Oct. 8–11, 1972. Permission to copy is restricted to an abstract of not more than 300 words. Illustrations may not be copied. The abstract should contain conspicuous acknowledgment of where and by who the paper is presented. Publication elsewhere after publication in the JOURNAL paper is presented. Publication elsewhere after publication in the JOURNAL OF PETROLEUM TECHNOLOGY or the SOCIETY OF PETROLEUM ENGINEERS JOURNAL is usually granted upon request to the Editor of the appropriate journal provided agreement to give proper credit is made. provided agreement to give proper credit is made. Discussion of this paper is invited. Three copies of any discussion should be sent to the Society of Petroleum Engineers office. Such discussion may be presented at the above meeting and, with the paper, may be considered for publication in one of the two SPE magazines.

Introduction
The purpose of this paper is to discuss the various aspects of dual gas lift installations. This discussion includes types of installations, types of valves, installation design, control and operation.
The design of single gas lift installations, for both continuous and intermittent lift, has been resolved to the extent that it is no longer considered to be a difficult problem. If proper well information is available, an installation can be designed to properly produce and carry the well to depletion. With the advent of multiple completions, the design of two or more strings of gas lift valves to operate in a common annulus has now become a reality.
Dual installations are by far the most common of the multiple completions. The installation of gas lift valves to lift two zones from a common annulus for gas is common practice. However, the operation of these systems has been inefficient in many cases. For some installations this has resulted from faulty equipment and in others, faulty design. The faulty design may have been due in part to incorrect well information and to the procedure in selecting valve settings. The availability of accurate reservoir and well information for both zones is extremely important in the design of a good dual gas lift installation.
TYPES OF INSTALLATIONS

Introduction
There are many types of installations that may be installed to lift fluid from dually completed wells. Some of these are dictated by prevailing conditions such as casing size, distance between zones, preinstalled gas lift mandrels; well conditions such as sand, scale and paraffin; and, finally, the opeator's preference. The paraffin; and, finally, the opeator's preference. The more common types of installations are as follows:
Parallel Tubing String Installations Parallel Tubing String Installations The most common type of dual installation and the one most highly recommended is that of parallel tubing strings as noted in Figure 1. For casing sizes of 7" and larger, ample space is available for running two strings of 2 3/8" tubing or larger. This is true for most types of gas lift valves and mandrels.