Thesis Abstract

With ever increase in crude oil demand and the presently low cost per barrel, it is highly uneconomical for new exploration, thus there is now need to maximise recovery from the existing reservoir. Surfactant Polymer flooding is an improved oil recovery that can mobilise more oil to the surface from an oil reservoir.

In this paper, we investigated the potential application of SP flooding in a shallow oil reservoir X, located in the Central-Onshore of the Niger Delta. Four different rocks were used namely; ROBU synthetic cores (2 different porosity and permeability classes), a widely accepted model rock (Bentheimer sandstone) and a low permeability-high porosity reservoir rocks (obtained from the Central Onshore of the Niger Delta) were used..Hengfloc 63020 polymer in combination with Shell Enordet O242 surfactant (supplied by Shell research centre) constituted the slug used in this work. The reservoir condition was simulated using the reservoir oil and low salinity brine of 2300ppm.

Initial water-flooding experiments were carried out on the crude oil sample at surface conditions, which was followed by surfactant-polymer flooding at same conditions. Furthermore, analysis of the effluent collected during the experiment was carried out to determine oil recovery.

The results show that firstly, SP flooding can mobilize substantial amount of by-passed oil in the reservoir after the water-flooding. Secondly, a remarkable increase in oil recovery when compared with the literature data shows its applicability in the reservoir of interest. Recovery of above 37% of the OIIP and displacement efficiency of over 50% was recorded.

Accordingly, surfactant-polymer recovery technique is applicable in the Niger Delta, and similar depositional environments. Thus, the practice of abandoning depleted reservoirs in this region can be replaced by using surfactant-polymer flooding to recover residual oil entrapped in the reservoirs.

KEYWORDS Oil recovery, surfactant-polymer flooding, chemical slug, polymer, surfactant, chemical enhanced oil recovery, displacement efficiency, Niger delta crude.

Thesis Overview

INTRODUCTION

1.0 OVERVIEW OF THE STUDY

For most of the oilfields in the world, at least half of the reserved oil is left behind after the primary (natural flow) method is exhausted.Numerous techniques have been established inthe past decades aiming to enhance the energy of the viscous fingered/channelled reservoirs after extensive water injection to improve oil recovery. This process is called improved oil recovery (IOR). Among all the IOR techniques, surfactant- polymer flooding is one of the most promising techniques because of its effectiveness in improving displacement efficiency.