Optimal Development of a Natural Gas Transmission System
Authors: Heideman John C. 
Published: December 2007

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Abstract
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.