ASSESSMENT OF SAFE AND COST EFFECTIVE METHODS TO MAXIMIZE PRODUCTION (PROFITABILITY) FROM A GAS-LIFTED FIELD
CHAPTER ONE
1.0 INTRODUCTION
1.1 Background of Study
After the completion of a given well or group of wells, they are then put under production. During this phase of operation, every operator looks for means to minimize operating cost and maximize cumulative oil production in the most cost-effective manner for the entire field. This stage of operation is what is generally termed production optimization. A true optimization requires an operator to take a logical look at the field’s production systems from the sub-surface to surface facilities.
Production optimization implies striking a balance between production deliverability of the wells and demand which basically aim at increasing the rate at which a well flows fluid from the reservoir without restriction to the surface storage tank(s). One of the most common means of conducting production optimization is through nodal analysis. This is normally done to optimize production from single wells or other smaller production systems. Large complex systems demand a much more sophisticated approach to predict the response of a large complicated production system accurately and to examine alternative operational scenarios efficiently. Beggs (1991) stated that optimization is directly dependent on some functions. The functions may be a single variable or more than one variable (multivariate optimization). A well is said to be optimized when it is producing at optimum conditions with minimum problems (Bath, 1998).
Most wells upon completion in oil producing sand formations will flow naturally for some period of time. Production at this stage will be initiated by the existing reservoir pressure. This reservoir pressure will provide all the initial energy needed to bring fluid from the well to the surface. As the well produces, this energy is consumed and at some point, there will no longer be enough energy to bring fluid to the surface. The well at this state, will cease to flow. When this happens, there is need for the well to be put under some form of artificial lift method in order to provide the energy needed to bring the fluid to the surface. It should be pointed out that artificial lift systems can also be used in de-watering of gas wells to sustain production.Basically, there are two methods of artificial lift systems. These are: pumping system (electrical submersible pump, sucker rod etc.) and Gas lift system.
