CHAPTER 1

INTRODUCTION

1.0 Background of Study

Oil and Gas is considered to be one of the major sources of energy in the world due to its high energy density, easy transportability, and relative abundance. It is a vital factor in every country’s economy. Almost all items that we buy, use, and consume are products of oil. The EIA (Energy Information Administration) stated that the world consumption of crude oil daily is 85.64 million barrels, which is equivalent to 2 liters of oil per day per person.

Generally, oil can be produced from the reservoir by the stored energy of the oil in the reservoir. This energy is obtained by the difference between the reservoir and wellbore pressures. If this difference is high, the well will be capable of producing naturally. Most oil wells worldwide produce naturally in their early lives until there is a decrease in the reservoir pressure which leads us to enhanced oil recovery.

When a well has been producing for a period of time, there will be decrease in reservoir pressure and as a result the difference between reservoir and wellbore pressure will decline. So, the energy in the well will not be able to lift oil up to surface, or it might lift oil to the surface but in less than economic volume. At this stage, artificial lift is introduced and it can be utilized to overcome this issue by reducing the wellbore pressure. This reduction will bring back the essential difference between the reservoir and wellbore pressure so oil can be extracted and lifted up to the surface.

One of the most important roles of artificial lift is to maximize the production rate from flowing wells. Artificial lift can be divided into two types, based on lifting mechanism: gas lifting and pumps.  The gas lifting method makes use of a compressed gas that is injected from the surface to certain points in the tubing. This gas will lower the density of the fluid column in the tubing causing a reduction in the wellbore pressure and therefore increasing production. The pumping method, on the other hand, involves setting the pump at a certain depth inside the tubing that will cause it to be submerged below the liquid level. This pump will lower the wellbore pressure and hence increase the drawdown, thereby boosting production. The most common artificial lift methods used are as follows:

• Electrical Submersible Pump (ESP)
• Sucker Rod Pumps (SRP)
• GasLift (GL)
• Plunger Lift Pumps (PLNG)
• Progressive Cavity Pumps (PCP)
• Hydraulic Pumps (HP)

Bearden (2007), stated that ESP is the most competent and consistent method of artificial lift when moderate to high volume of oil needs to be lifted from the well. He also estimated the lifting capacity of ESPs to be as low as 150 barrels per day and as high as 150,000 barrels per day. Fig 1.1 below shows the various types of artificial lifts and their utilization worldwide.

Fig 1.1 Artificial lift types and their utilization.

1. Statement of Problem

A major challenge faced in lifting oil and gas from the reservoir through the production tubing to the surface facilities is an unnecessary production decline which is as a result of low reservoir pressure and it is a serious problem in the petroleum industry today. This decline may be as a result of mismanagement of wells, excessive pressure drops along the production system, oversized or undersized tubing, and improper perforation method etc. A change in any component of the production system may lead to a change in the pressure drop behavior of the other components since the various components are interactive.

This study shows the design of an ESP artificial lift system and production optimization of Well J-50 is a new horizontal well in a Niger Delta field. In other to optimize production and produce about 10,000bopd as the desired rate of production, ESP was recommended to be designed for the well to achieve optimum production by.

1. Methodology

The method to be used for this work is the analytical method of ESP design and using the software PROSPER. In the analytical method the following steps will be taken to design the ESP design;

• Collection of basic data
• Calculation of production capacity
• Gas calculations
• Determination of Total Dynamic Head (TDH)
• Pump-type selection and calculation of pump stages
• Optimum size of components
• Electric cable selection

In using PROSPER (Production System Performance Analysis Software) to design the ESP system the following steps will be followed;

• Using existing PVT and VLP data has a basis of new analysis.
• Calculating pump intake and outlet pressures.
• Designing an ESP system
• Evaluating pump operating point sensitivities.
• Calculate a flowing gradient for an ESP equipped well.

1.3 Aim and Objectives

The major aim of carrying out this research is to optimize production for well J-50 by    designing an artificial lift system while its objectives are as follows;

• To design an artificial lift system (ESP) for a well that the production rate has declined.
• To boost production for a producing well and increase revenue.
• To describe and design an operation of ESP for a given well.

1.4 Significance of study.

The significance of this study in the petroleum industry is to show the importance of designing ESP for a new well and also the use of artificial lift in maximizing oil production.

1.5 Scope and limitations of Research

The scope of this research is limited to the use of manual method and PROSPER in designing an ESP for artificial lift so as to optimize production. There are other softwares that can also be used in designing an ESP System but for this project PROSPER is used due to availability. The study is conducted in a Niger Delta reservoir and a suitable ESP design will be done to increase the well production potential.