Basic Theory Gas Pipelines - Bener.docx

Basic Theory Gathering pipeline system is a series of pipelines that flow from the well production facilities in a producing field to a gathering “trunk” pipeline. Gathering systems typically fall into one of four categories: 1. Single-trunk systems with “lateral” lines from each well production facility. 2. Loop systems, in which the main line is in the shape of a loop around the field. 3. The multiple-trunk system, in which there are several main lines extending from a central point. 4. Combinations of categories 1 through 3. Gathering systems typically require small-diameter pipe that runs over relatively short distances. The branch lateral lines commonly are 2 to 8 in. Gathering systems should be designed to minimize pressure drop without having to use large diameter pipe or require mechanical pressure-elevation equipment to move the fluid volume. For natural-gas gathering lines, the Weymouth equation can be used to size the pipe. In this project, the equation that used to calculate the optimum diameter size of pipeline is Weymouth equation. The Weymouth equation was developed from the fundamental energy equation for compressible flow. The equation was developed for turbulent flow in long pipelines. So, for low flows, low pressures, or short pipes, it may not be applicable.

Figure 1 Weymouth Equation for Calcualte Optimum Pipe Diameter Size Where, Qg

=

gas-flow rate, MMscf/D,

Dopt =

optimum pipe inside diameter, in.,

T

=

average temperature of gas at inlet, °R,

SG

=

specific gravity of gas,

Z

=

average compressibility factor for gas, dimensionless.

P1

=

average Pressure, psia,

Reference : Pipelines – Petrowiki. Accesed from https://petrowiki.org/Pipelines on April 1st 2019.