CHAPTER ONE

INTRODUCTION

Many reservoirs are comprised of relatively young sediments, which are so poorly consolidated that sand will be produced along with the reservoir fluids unless the production rate is reduced significantly. Sand production leads to many numerous production problems including erosion of down hole tubular, valves, fitting and surface flow lines, collapsed casing because of lack of formation support. Thus a means to eliminate sand production without greatly limiting production rates is desirable.

Sand production can be controlled using different methods but the method of utmost importance to this project is the mechanical method which basically involves the use of gravel pack (GRAVEL PACKING).

This method is considered the oldest and most effective sand   control mechanism. It is simply a down hole filter designed to prevent the production of unwanted sands which involves the placement of gravel across a perforated interval in the sand screen annulus and also in the perforation tunnel to prevent the influx of sand.

Inaccurate determination of gravel pack size, could lead to sand influx which could be detrimental to both the technical and economic aspect of production which is the overall objective of this project aimed at identifying means to selectively select appropriate gravel pack sizes from formation sands produced through sieve analysis to meet optimum sand control for maximum production without any detrimental effect to production hard wares.

In a gravel pack completion, sand that is larger than the average formation sand grain is placed between the formation and a screen or slotted liner with the aim of retaining most of the formation sand, but letting  very fine particles through it and be produced.

The two most common types of gravel pack completion are the inside casing gravel packing or internal gravel packing (IGP) and underreamed gravel pack or external gravel pack (EGP). The underreamed casing gravel pack provides better conductivity through the gravel but is limited to single zone completion.

1.1 AIMS AND OBJECTIVES

This project is aimed at

1. To study   the various types of gravel packing methods  used in  the petroleum industry.
2. To analyze sieve analysis data of formation sands gotten from OBEN13L in other to determine the appropriate gravel pack size used.
3. To make conclusions on the state of OBEN WELL 13L on the basis of sieve data analysis and give possible recommendations.

1.2 SCOPE AND LIMITATION

The scope of this project is limited to the mechanical method  of sand control with more emphasis on the sieve analysis of formation sands gotten from OBEN13L.

1.3 METHODOLOGY

The method to be adopted for this project is the use of sieve analysis and sucier correlation to determine the gravel pack size to be used  for OBEN WELL 13 with formation sands gotten  from  the case study as mentioned above and useful information gotten from the internet, textbooks, petroleum journals. This method simply involves collecting core samples  and running them through different sieves with different opening sizes, usually sieves with larger openings at the top and sieves of smaller opening at the bottom and plotting each weight retained on each sieve against the sieve opening size to determine the average formation sand size which is used to find accurate gravel size using  sucier correlation.