Natural Gas Liquids Supply And Demand Balances In Alberta
Authors: Naini A. 
Published: March 2010

Natural gas consists primarily of mixtures of hydrocarbon gases, predominantly methane, along with smaller amounts of natural gas liquids and non-hydrocarbons. This paper provides descriptively and quantitatively a framework for evaluating and balancing the potential sources of natural gas liquids supply and demand in the province of Alberta for the period 1988 to 2000.

Introduction

Natural gas consists primarily of mixtures of hydrocarbon gases, predominantly methane, along with smaller amounts of ethane, propane, butanes and pentanes plus which are called natural gas liquids (NGLs), and non-hydrocarbons such as nitrogen, oxygen, water, carbon dioxide, hydrogen sulphide, and mercaptans.

Ethane is a part of natural gas which can be separated out (through application of high pressure and temperatures) at gas plants. Ethane is an important petrochemical feedstock for the production of ethylene. It is also used as a miscible agent for enhanced oil recovery. Propane and butanes are by-products of natural gas and crude oil feed to distilling, which are obtained from gas plants and refineries. Propane is used primarily as a fuel and as miscible flood for enhanced oil recovery. However, in contrast to propane, butanes are used primarily as feedstock in refineries and petrochemical plants. They are seldom used in miscible floods except when entrained in NGL mixes. Pentanes plus is a by-product of natural gas which is obtained from gas plants as well as condensate from crude oil. Pentanes plus is used as a refinery feedstock and as a diluents in reducing viscosity of bitumen and conventional heavy crude oil to allow conventional pipelining.

The purpose of this paper is to describe and project supply and demand for NGLs in the province of Alberta for the period 1988 to 2000. The Gas Energy Management Model (GEMM) and Energy Requirements Model of Alberta (ERMA) are used for the projections of supply and demand for NGLs, respectively. The major assumptions used for both models are adopted from the high case of "Energy Requirements in Alberta, ERCB Report 89-A ".

The high case is an optimistic pricing scenario from an upper bound forecast that assumed the plant gate price of natural gas (in 1988 constant dollars) would increase to $4.36 per GJ by the year 2000 from the 1988 level of $1.57 per GJ.

Because the projections of NGLs are shown in petajoules, the approximate volume equivalent of one petajoule for each liquid is as follows:

List of NGLs are shown in petajoules (Available In Full Paper)

In the first section of this paper, three sources of NGL supply are described. In the second section, uses of NGLs within Alberta are identified. In the third section, the projection of supply and demand for NGLs along with the major input assumptions are described. In the last section, NGL supply and demand balances are presented.

Alberta Sources of Natural Gas Liquids

In Alberta, the supply sources of gas co-products (NGL and sulphur) are gas processing and reprocessing plants* and crude oil refineries.

The main products of gas processing plants are propane, butanes and pentanes plus.