Optimal Development of a Natural Gas Transmission System
Authors: Heideman John C. 
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.

A mathematical procedure for optimizing the long-term operating policy of a natural gas transmission system has been developed. The procedure determines average and peak production procedure determines average and peak production rates for supply reservoirs, peaking and injection rates for storage reservoirs, schedules for adding compression at prescribed pipeline compressor sites, and schedules for drilling wells and adding compression at supply reservoirs such that present-value profit is maximized while forecast long-term customer demands are met. Application of the procedure to a sample system shows that present-value profit can be increased substantially through a combination of investment reduction and accelerated liquids production.

The procedure requires a steady state model of the transmission system. Because only a few critical segments limit the capacity of the system, it is sufficient merely to compute the capacity of these segments. This is accomplished by dividing the system into a number of coupled subsystems, each containing a critical segment, and then performing a steady state analysis of each subsystem. For each subsystem, the procedure requires that supply equal demand, while procedure requires that supply equal demand, while flow through the critical segment must not exceed the capacity.

The procedure also requires a steady state model of each supply reservoir producing to the transmission system. Each supply reservoir is assumed to have a uniform pressure which is a function only of the remaining reserves. The effect of depletion rate on ultimate recovery in waterdrive reservoirs is approximated by a linear relationship. All of the wells producing from a supply reservoir are described by a single set of well deliverability curves. Gas shrinkage due to liquids extraction and fuel consumption is taken into account. For each supply reservoir, the procedure requires that production rates not exceed reservoir deliverability and that cumulative production not exceed recoverable reserves.

Optimization of the operating policy is accomplished via a nonlinear programming algorithm which partitions the variables into flow variables and investment variables. The algorithm uses linear programming procedures to allocate production and a steepest ascent technique to production and a steepest ascent technique to determine investment policy.

Introduction

The problem considered in this paper is that of determining the optimal long-term policy for meeting the customer demands of a natural gas transmission system.