Development of Coning Correlations for Oil Rim Reservoirs Using Experimental Design and Response Surface Methodology
Development of Coning Correlations for Oil Rim Reservoirs Using Experimental Design and Response Surface Methodology.
ABSTRACT
Proper management of thin oil rim reservoirs is required to maximize recovery and minimizes coning tendencies.
The objective of this study is to determine the effect of reservoir and fluid properties on coning tendencies in thin oil rim reservoirs and to develop numerical correlations to predict oil recovery and water break through time for these reservoirs.
Numerical correlations for the prediction of recovery and water breakthrough time using response surface methodology have been developed.
The thin oil rim reservoir was represented using a generic simulation box model. Production rate, horizontal well length, oil viscosity, vertical landing of well from the gas-oil contact (GOC), vertical permeability and anisotropy ratio were varied and their effects on oil recovery, reservoir pressure, water cut and breakthrough time were studied.
The results show that an increase in horizontal well length reduces the coning tendencies and improves recovery of oil.
Increasing viscosity of oil (reducing oil mobility) increases the coning tendencies whilst reducing the productivity index of a well hence decreasing recovery. An increase in the horizontal well landing position from the gas-oil contact (GOC) results in an increase in water cut.
An increase in vertical permeability and vertical anisotropy ratio both increases the coning tendencies in thin oil rim reservoirs.
TABLE OF CONTENT
LIST OF TABLE….iv
LIST OF FIGURES …. v
DEDICATION…….. vii
ACKNOWLEDGEMENT.. vii
1.0 INTRODUCTION
1.1 OVERVIEW .. 1
1.2 PROBLEM STATEMENT…… 3
1.3 AIMS AND OBJECTIVES ….. 4
1.4 SCOPE……… 4
1.4 ORGANIZATION OF THE WORK……4
2.0 LITERATURE REVIEW
2.1 INTRODUCTION …… 6
2.2 CONING EVALUATION STUDIES………. 7
2.2.1 Analytical and Experimental Studies…. 7
2.2.2 Numerical Simulation Studies ………. 12
2.3 EXPERIMENTAL DESIGN AND RESPONSE SURFACE METHODOLOGY 18
3.0 RESEARCH METHODOLOGY…….. 20
3.1 INTRODUCTION …. 20
3.2 Generic Simulation Model for Thin Oil Rim reservoir …. 20
3.3 PARAMETRIC STUDIES ………. 22
3.4 RESPONSE SURFACE METHODOLOGY …. 22
4.0 RESULTS AND DISCUSSIONS
4.1 INTRODUCTION ………………. 24
4.2 PARAMETRIC STUDIES …. 24
4.3 CRITICAL RATE DETERMINATION. 40
4.4 RESPONSE SURFACE MODEL …….. 42
4.4.1 Correlation Development…….. 42
4.4.1.1 Oil cumulative recovery (CR)……… 43
4.4.1.2 Field water break through time ………… 46
5.0 CONCLUSIONS AND RECOMMENDATIONS
5.1 SUMMARY AND CONCLUSIONS .. 49
5.2 RECOMMENDATIONS….. 50
NOMENCLATURE ….. 52
REFERENCES ………… 53
APPENDIX…….. 56
INTRODUCTION
Coning is the result of high pressure gradient around the producing well which causes the oil-water contact to rise and the gas-oil contact to depress near the wellbore.
Gravitational forces tend to segregate the fluids according to their densities. However, when gravitational forces are exceeded by the flowing pressures (viscous force), a cone of water and/or gas will be formed which will eventually penetrate the wellbore (Beveridge, 1970).
Figure 1.1 is a schematic illustrating the phenomenon of water coning in a producing vertical well. This dynamic force due to wellbore drawdown causes the water at the bottom of the oil layer to rise to a certain point at which the dynamic force is balanced by the height of water beneath that point.
As the lateral distance from the wellbore increases, the pressure drawdown and the upward dynamic forces decrease.
Thus, the height of the balance point decreases as the distance from the well bore increases. Therefore, the locus of the balanced point is a stable cone shaped water oil interface.
At this stable situation, oil flows above the interface while water remains stationary below the interface (Namani, 2007). This also applies to gas coning.
REFERENCES
Beveridge S.B, Coats K.H, Alexandre M. T (1970) “NUMERICAL CONING APPLICATION.” The Journal of Canadian Petroleum Technology
Benamara A, Tiab D (2001) “GAS CONING IN VERTICAL AND HORIZONTAL WELLS”: A NUMERICAL APPROACH. Society of Petroleum Engineers Journal (SPE 110026).
Koederitz F. L (2001) “LECTURE NOTES ON RESERVOIR SIMULATION”. World Scientific. Page 7.
Marcano L, Wojtanowicz A.K (2005). “DUAL GAS LIFT IN IN WELLS WITH DOWNHOLE WATER SINK TECHNOLOGY: A FEASIBILITY STUDY”. Society of Petroleum Engineers, Production and Facilities (15) 4.
Wojtanowicz A.K, Xu H (1995). DOWNHOLE WATER LOOP: A NEW COMPLETION METHOD TO MINIMIZE OIL WELL PRODUCTION WATER CUT IN BOTTOM DRIVE RESERVOIRS”. The Journal of Canadian Petroleum Technology, Vol 34, No 8.
Permadi P (1996) “FAST HORIZONTAL WELL CONING EVALUATION METHODS”. Society of Petroleum Engineers Journal. (SPE 37032)
Joshi S.D (1988). “AUGMENTATION OF WELL PRODUCTIVITY WITH SLANT AND HORIZONTAL WELL”SPE Philips Petroleum Co. Journal of PetroleumTechnology. 54
Qin W, Wojtanowicz A.K, White D. C (2014) “NEW COLD PRODUCTION TECHNIQUES FOR HEAVY OIL WITH STRONG BOTTOM WATER DRIVE”. Society of Petroleum Engineers Journal.
