Diagnostic Plots for Analysis of Water Production and Reservoir Performance

Diagnostic Plots for Analysis of Water Production and Reservoir Performance.

ABSTRACT  

The research is aimed at the understanding of the various diagnostic plots for the analysis of water production that are available as well as the application of these methods in a case study. It also aimed at the establishment of a work flow for the evaluation of water production mechanisms. A workflow was developed that combines numerical simulation and diagnostic plots to analyze the water production performance in a reservoir. This workflow was validated using a case study.

The multi-layer reservoir model with varying vertical permeability was constructed using a numerical simulator with the reservoir properties of the case study. Trends from the field data were analyzed using the trends observed from the simulated data as templates. For the production wells, oil rate and water rate versus time plots as well as the Xplot were used to evaluate water production characteristics of the case study.

The water-oil ratio (WOR), WOR derivative and X-Plot were used for the field production diagnosis while the Hall and the Hearn Plots were used for the water injection well diagnosis. The results of the diagnostic plots showed that multi-layered channelling was the controlling mechanism and the cause of the water production in the case study. For the injection wells, the plots indicated that some wells in the case study had the problem of extensive near wellbore fracturing while other wells had the problem of wellbore plugging.

TABLE OF CONTENTS

SIGNATURE PAGE………………………………………………………………………………………………… i
TITLE PAGE…………………………………………………………………………………………………………..ii
ABSTRACT …………………………………………………………………………………………………………..iii
DEDICATION……………………………………………………………………………………………………….. iv
ACKNOWLEDGEMENT…………………………………………………………………………………………. v
TABLE OF CONTENTS ………………………………………………………………………………………….vi
LIST OF FIGURES …………………………………………………………………………………………………ix
LIST OF TABLES………………………………………………………………………………………………….xii
LIST OF APPENDICES………………………………………………………………………………………… xiii

CHAPTER 1 …………………………………………………………………………………………………………. 1
1.0 INTRODUCTION………………………………………………………………………………………………. 1
1.1 Description of Problem……………………………………………………………………………………. 1
1.2 Study Objective………………………………………………………………………………………………. 2
1.3 Scope of Work………………………………………………………………………………………………… 2

CHAPTER 2 …………………………………………………………………………………………………………. 3
2.0 LITERATURE REVIEW …………………………………………………………………………………….. 3
2.1 Source of water………………………………………………………………………………………………. 3
2.1.1 Sweep water …………………………………………………………………………………………… 4
2.1.2 Good water …………………………………………………………………………………………….. 5
2.1.3 Bad water……………………………………………………………………………………………….. 5
2.2 Water Production Mechanism………………………………………………………………………….. 7
2.3 Causes of premature water production…………………………………………………………….. 7
2.3.1 Channels behind casing ………………………………………………………………………….. 8
2.3.2 Barrier breakdowns…………………………………………………………………………………. 8
2.3.3 Completions into or near water………………………………………………………………… 8
2.3.4 Coning and cresting………………………………………………………………………………… 8
2.3.5 Channelling through higher permeability zones or fractures. …………………….. 9
2.3.6 Fracturing out of zone……………………………………………………………………………… 9
2.4 ReservoirPerformancePlots and Analysis for WaterProduction ……………………….. 10
2.4.1 Decline Curve Analysis………………………………………………………………………….. 11
2.4.2 Log Of Water Cut or Oil Cut Versus Cumulative Production …………………….. 13
2.4.3 Fetkovich Type Curves ………………………………………………………………………….. 14
2.4.4 Omoregie and Ershaghi (X-Plot)……………………………………………………………… 15
2.4.5 Hall and Hearn Plot for Injectors …………………………………………………………….. 17
2.4.6 Diagnostic Plot ……………………………………………………………………………………… 19

CHAPTER 3 ……………………………………………………………………………………………………….. 24
3.0 METHODOLOGY……………………………………………………………………………………………. 24
3.1 Flowchart for Evaluation of water production mechanism …………………………………….. 24
3.1.1 Sonic Tool…………………………………………………………………………………………….. 27
3.1.2 Treatment……………………………………………………………………………………………… 27
3.1.3 Monitoring…………………………………………………………………………………………….. 27
3.2 Case Study One…………………………………………………………………………………………….. 27
3.2.1 Field Production Performance Evaluation……………………………………………….. 31
3.2.2 Field Production Data Diagnostic Plots…………………………………………………… 32
3.2.3 Field Injection Performance Evaluation…………………………………………………… 32
3.2.4 Injection Well Diagnostic Plots……………………………………………………………….. 32

CHAPTER 4 ……………………………………………………………………………………………………….. 34
4.0 RESULTS AND DISCUSSION OF RESULTS …………………………………………………….. 34
4.1 Evaluation of Reservoir Performance Trends…………………………………………………….34
from Simulated Data
4.1.1 Analysis of Simulated Oil Rate and Water Rate Plots……………………………….. 34
4.1.2 Analysis of X-Plot Simulated Data ………………………………………………………….. 40
4.2 Evaluation of Reservoir Performance trends from…………………………………………….43
Field Case Study
4.2.1 Analysis of Field Oil Rate and Water Rate Plots ………………………………………. 43
4.2.2 Analysis of Field X-Plot………………………………………………………………………….. 45
4.3 Diagnosis of Simulated Reservoir Production Performance …………………………….. 50
4.4 Diagnosis of Reservoir Production Performance …………………………………………….. 52
4.5 Injection Well Performance …………………………………………………………………………… 54
4.5.1 Simulated Injection Well Performance…………………………………………………….. 55
4.5.2 Field Water Injection Performance…………………………………………………………. 54
4.6 Injection Well Diagnosis ……………………………………………………………………………….. 57
4.6.1 Simulated Water Injection diagnosis ………………………………………………………. 57
4.6.2 Field Water Injection Diagnosis……………………………………………………………… 60
4.7 Guidelines…………………………………………………………………………………………………….. 62

CHAPTER 5 ……………………………………………………………………………………………………….. 63
5.1 SUMMARY AND CONCLUSIONS…………………………………………………………………….. 63
5.3 RECOMMENDATIONS……………………………………………………………………………………. 64
REFERENCES ……………………………………………………………………………………………………. 65

INTRODUCTION   

Produced water is any water that is present in a reservoir with the hydrocarbon resource and is produced to the surface with the crude oil or natural gas. This water could either come from an aquifer or from injection wells in water flooding process. The production of this water alongside the oil from any reservoir is a condition that is natural in all reservoirs. It is expected that water production would increase with the life of the reservoir. However, a premature increase in the production of water in any reservoir is an undesirable condition.

Excess or premature water production, exists with associated cost implication on the surface facilities, artificial lift systems, corrosion and scale problems. Another effect that ensues is a decrease in the recovery factors as oil is left behind the displacement front, thereby reducing the performance of the reservoir. All these along with the decrease in the quantity and quality of the oil imply a reduced profitability.

Globally, as at 2002, analysis showed that three barrels of water is produced to one barrel of oil and the cost of water handling ranges from 5 to 50 cents, where this cost is a function of the water cut. It is therefore imperative that actions be taken to reduce this adverse effect, as this will not just lead to potential savings but its greatest values comes from potential increase in oil production and recovery. To control the produced water effectively, the source or the mechanism of the water problem must be identified. 

REFERENCES

Bailey B, Crabtree M, Tyrie J, Elphick J, Kuchuk F, Romano C, Roodhart L,
Water Control, Oilfield Review 12 (Spring 2000) 30-51.

Bondar Valentina, 1997, The Analysis and Interpretation of Water- Oil Ratio
Performance in Petroleum Reservoir, Moscow State Academy of Oil and Gas,
Russia

Chan, K.S.: Water Control Diagnostic Plots, paper SPE 30775, SPE Annual
Technical Conference and Exhibition, Dallas, October 22-25

Dake L. P 1978 Fundamentals of Reservoir Engineering Elsevier Publishing,
Amsterdan, Netherlands, pp 345-348

Ershaghi, I. And Omoregie, O. A method for Extrapolation of water cut versus
recovery plots”, JPT (February 1978), 203-204

Ershaghi, I. and Abdassah, D. A Prediction Technique for Immiscible
Processes Using Field Performance Data, JPT (April 1984), 664-670

Ezekwe Nnaemeka, 2010 Petroleum Reservoir Engineering Practice,
Prentice Hall Publishing Company, pp 728-734

Fetkovich M. J. ”Decline Curve Analysis using Type Curve” SPE 04629 (1067-1077).

StudentsandScholarship Team.