The water/oil ratio (WOR) is one of the more important metrics in calculating the economic value of a producing well. Reservoir engineers calculate water cut to update reserve and ultimate oil recovery estimates and refine the decline curve over the life of a well. With a WOR trending toward 100%, production engineers, reservoir engineers, and even financial analysts need to pool their skills and experience to analyze well performance and determine the well’s economic future. The barrel price of oil, utilities, maintenance, water remediation and disposal, land, and other expenses factor into the profitability equation.
No reservoir team wants to shut a well without exploring viable options to mitigate high water cut oil production. Reservoir teams gain a more detailed understanding of the factors that affect WOR by integrating and visualizing production data with data that characterize developing reservoir conditions. With this insight, engineers can more readily identify the factors or causes of increasing WOR and determine effective mitigation strategies.
Compare High Water Cut in Oil Production With Other Wells
The high water cut in oil production for a specific well can be compared with decline curves for nearby wells or wells with similar geologic, and geophysical attributes. Production data, completion information, as well as secondary or tertiary recovery techniques for similar wells provide additional guidance regarding reservoir characteristics and recovery techniques and successful and unsuccessful mitigation efforts.
Without the right tools, comparing a wide range of well data can be time-consuming. Comparisons are made far more efficiently when well data is integrated and evaluated visually in 2D graphs and 3D animations over time. Shared access to all relevant well data and a collaborative visualization environment enables well-by-well comparison, assessment of the complete well program, e.g., injectors and producers, or even evaluation of the entire oil field. With these capabilities, reservoir teams gain a far better understanding of the efficacy of previous high water cut oil production mitigation efforts.
Identify Factors Influencing High Water Cut in Oil Production
Visualization of reservoir conditions and monitoring production data also makes it easier to identify factors that are likely to influence high water cut. Production data reported on a spreadsheet is not as meaningful as production data visualized in context of the local geology and offset wells. Gradual or sudden changes in water cut are more easily diagnosed when production data is analyzed along with detailed, relevant data that document well planning, drilling, completion, and operations of all wells.
Easy access to this level of detail, allows reservoir engineers to more readily and confidently identify problems, such as those listed below:
|Problem||Identified By||Mitigation Strategy|
|Casing leak caused by sucker rod abrasion||3D visualization of the wellbore shows a severe dogleg at the water zone level||Cementing, patch tubing|
|Incomplete plug closure in depleted zone||Earth model shows where tracers added to the injection well are migrating to the production well||Install mechanical or inflatable plugs to close the gap|
|Water zone not completely isolated from pay zone||Latest seismic survey and review of 3D subsurface formation model reveals miscalculation in initial depth measurement for the zone||Install mechanical or inflatable plugs to close the gap|
|Coning in vertical wells||Comparison of the seismic survey with increasing WOR indicates a rise in oil-water-contact (OWC) across wells||Decrease well production rate; Perforate the water zone or use tubing and annulus to coproduce separately. |
Well recompletion at a different depth.
Horizontal wells for future development to minimize drawdown.
That’s certainly not a complete list of the problems that lead to high water cut in oil production, but it does illustrate how access to relevant well and subsurface data—and the ability to visualize it—help isolate the source of water, identify the problem, and propose appropriate solutions.
CoViz 4D to Identify High Water Cut in Oil Production
Reservoir engineers contending with high water cut in oil production can benefit from the capabilities of CoViz 4D, a versatile data integration and visualization software developed for the petroleum industry. CoViz 4D easily integrates and visualizes a wide range of data types that reservoir and production engineers, geologists, and petrophysicists rely on. By combining these data to provide a detailed 3D visualization of subsurface environments, petroleum professionals gain a more detailed understanding of the interplay of reservoir characteristics and development decisions that affect well performance.
CoViz 4D is exceptional in enabling reservoir engineers to visualize changing reservoir conditions and their impact on production.
CoViz 4D is exceptional in enabling reservoir engineers to visualize changing reservoir conditions and their impact on production. The ability to analyze trends in WOR over time, in a single well or in comparison to nearby wells, and review the effectiveness of previous mitigation techniques, gives reservoir engineers greater confidence. With CoViz 4D, reservoir engineers gain insight into how to avoid potential water cut issues when planning future wells, monitor developing water cut metrics, identify problem sources, and devise appropriate mitigation strategies for high water cut in oil production.