Evaluation of viability of a crude oil reservoir using petrophysical parameters (a case study of agbara oil well reservoir in the niger-delta basin)

Thesis Overview

<p> </p><p><strong>&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;1.0 INTRODUCTION</strong></p><p>Generally, the major oil companies maintain their own research and development (R&amp;D) records and also, nurture in-house technological and engineering skills acquisition schemes. For this reason, some companies see the core activities needed before oil exploration as unrealistic if carried out, externally.</p><p>They now preserve only what is essential to evaluating the cost of exploration from a particular reservoir.</p><p>These core activities include the formation evaluation technique, which is applied to determine hydrocarbon saturation in a given reservoir, the determination of oil- in- place (OIP) or stock Tank Oil initially in Place (STOIIP) and the application of ultimate Recovery Factor (URF), based on analysis of some petrophysical parameters using current technology.</p><p>This research work gives attention to determining the most economical means of estimating the percentage of hydrocarbon saturation in a particular reservoir, and its recovery factor. A model called, Area – Depth concept model was developed to analytically estimate the quantity of crude oil deposits in a reservoir, using Agbara oil well reservoir as a case study. The basic economic measures that are related to oil production were evaluated. In this research, Archies’ Law was applied in the determination of water saturations at different zones in a particular reservoirs based on the log data of the petrophysical parameters from the Agbara oil well reservoir, in the Niger-Delta basin. &nbsp;This helps to determine the productive oil zones by estimating the percentage of hydrocarbon saturations in the reservoir. This study would help reduce considerably the overall cost involved in executing recovery process from a particular reservoir in order to achieve optimum yield.</p><p>There is no doubt in the fact that the world has consumed approximately 40 percent of the estimated recoverable reserves, i.e. more than one- third of the easily recoverable reserves have been found and consumed (Stela Shamon,1998).</p><p>When 50 percent of recoverable reserve is reached, production will inevitably go down because of the difficulty of extracting the rest. The only hope of extending the world’s oil reserve is to make a quantum leap in production from 35% to 60%.</p><p><strong>1.1 OBJECTIVES OF THE STUDY</strong></p><ol><li>To estimate the quantity of recoverable hydrocarbon in a reservoir and evaluate the recovery factor, by using the related petrophysical parameters.</li><li>To improve the efficacy of volumetric method in reservoir evaluation by using the area-depth concept model.</li><li>To determine the productive oil zones in a particular reservoir , by the use of Archie’s equations.</li></ol><p>4 &nbsp; &nbsp; To develop initialization algorithm for determination of</p><p>pressure gradient in a reservoir.</p><p>5 To evaluate the basic economic measures in relation to oil production.</p><p><strong>1.2 SIGNIFICANCE OF THE STUDY</strong></p><p>The significance of this research work will include:</p><ul><li>Provision of a background for easy interpretation of resulting drilling data before and during exploration.</li><li>Reduction in the overall drilling costs from a reservoir.</li><li>Improvement on the quality and quantity of crude oil recovered from a particular reservoir</li><li>Reduction in the cost of energy to consumers</li></ul><p><strong>1.3 LIMITATIONS OF THE STUDY</strong></p><ol><li>First, it would be impossible within the short time frame of this study to conduct extensive oral or written interviews outside Port Harcourt</li><li>Secondly, time factor would also not permit to deal exhaustively with the issues of management views arising from the first constraint.</li><li>Thirdly, the values of the petrophysical parameters from log readings used for these evaluations are only dependent upon the precision and accuracy of the instrument used.</li></ol><p><strong>&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; </strong></p><p><strong>1.4 &nbsp; &nbsp; &nbsp; METHODOLOGY</strong></p><p>The information for this study will be obtained from the following sources;</p><ul><li>Publications such as: Learned journals ,Internet and Seminars.</li></ul><p>Research findings from Schlumberger oil services Ltd and Chevron Nigeria Ltd, in Port Harcourt.</p><p>Data collected from actual drill samples during fieldwork was used for the analysis of formation evaluation. They were collated and analyzed. These data include the petro-physical parameters like porosity, permeability, resistivity, shaliness, lithology and formation temperature. These data would be used to evaluate the viability of a reservoir, by the use of formation factor and Archie’s Equation. Also, information on economic and management considerations would be obtained from interviews and observations during a visit to some selected companies in the Niger- Delta area.</p><p>The processes, economics and management of enhanced drilling techniques are pre-requisite for the actualization of these objectives.</p><p>Formation evaluation (Otherwise referred to as log Interpretation) is the process whereby physically measurable properties are translated into petrophysical parameters of interest. Some of the major petro-physical parameters that would be used in this research work, to determine and evaluate the viability of a crude oil reservoirs are as follows:</p><ul><li>Resistivity (R) :- The reluctance of a unit volume of formation (matrix + fluid) to the flow of electrical current</li><li>Porosity (ø):- This is the percentage of void space in a unit volume of rock.</li><li>Hydrocarbon saturation (S): This is the percentage of pore space filled with hydrocarbons (gas or oil).</li><li>Permeability (K):- This is the measure of the specific flow capacity or ease with which fluid flows.</li><li>Lithology (L):- This is the study of rocks to determine their character and composition</li><li>Shaliness (Vsh):- The fraction of a very fine grained detrital sedimentary rock composed of silt and clay. It is the volume of shale in a particular rock formation.</li><li>Water saturation (Sw)-: The percentage of the porous fraction of formation that contains water.</li></ul> <br><p></p>