Maximizing the recovery of hydrocarbon assets begins with a detailed understanding of geologic, geophysical, and petrophysical characteristics of the reservoir provided by seismic surveys, well tests, and reservoir models. With that information in hand, reservoir and drilling engineers can evaluate various wellpath options with the goal of reaching the target zone in the most cost-efficient manner. Once a wellpath plan is finalized, engineers then face the reality of drilling the well, perhaps the most challenging and critical step in the entire reservoir lifecycle.
All of the preliminary subsurface data that a reservoir team acquires can play a vital role in reducing targeting risks. And when real-time drilling data analysis is incorporated into 3D visualizations of geologic structures, engineers can gain insights while monitoring drilling progress and wellbore location to significantly reduce the risk of missing the target zone.
A brief review of the well planning and the drilling processes help illustrate how geologic, geophysical, and petrophysical data enhance the understanding of real-time drilling data to help reduce targeting risks.
Wellpath Planning: The First Step in Reducing Targeting Risks
The ability to access and visualize a detailed 3D representation of relevant subsurface data—geologic, geophysical, and petrophysical—enables planning and drilling engineers to collaboratively explore and evaluate reservoir characteristics that influence wellpath planning. Visualization and analysis of potential wellpaths allow drilling engineers to evaluate conditions at any level of detail. They can begin with a macro understanding of a reservoir and its potential, then focus on geologic and petrophysical characteristics of any portion of a potential wellpath to determine how variations along the wellpath should alter trajectories, dictate equipment requirements, and impact overall costs. With a better understanding of reservoir characteristics proximate to a proposed wellpath, a multi-disciplinary team can:
- determine the ideal target zone, based on characteristics such as highest resistivity (oil saturation),
- establish intermediate targets, using geologic data,
- avoid fault intersections, problem horizons, and proximity to oil-water contact,
- identify problematic geology that could impede drilling progress and add to drilling costs, and
- maintain proper spacing to avoid encroachment on nearby wells and jeopardize production.
A thorough analysis of the pros and cons of various wellpath plans helps reservoir and drilling engineers collaboratively develop the optimum plan to reach the target zone and cost-efficiently recover hydrocarbon assets.
Insight From Real Time Drilling Data Analysis Guides the Process
With an approved wellpath plan, drilling engineers can then use the 3D subsurface model and wellpath plan to closely monitor the drilling process using WITSML data. Real-time drilling data such as azimuth, inclination, and gamma ray produced by MWD and LWD tools—and transmitted to a WITSML server—can be incorporated and visualized into the 3D model to depict drill bit progress and wellbore location.
When real-time drilling data are used to visualize the progress of the drill bit and the location of the wellbore, in context of geologic structures and subsurface conditions, drilling engineers can:
- Compare the development of the actual wellbore against the planned wellpath to assess drilling accuracy, ensure that the intended wellpath intersects intermediate targets, and record any significant variations.
- Visualize the drill bit and wellbore location to confirm the trajectory is on-target relative to reservoir boundaries.
- Evaluate drilling performance based on location and surrounding geology to ensure downhole tools operate within their technical specifications.
- Perform automated clearance calculations ahead of the drill bit to determine if the current trajectory is appropriate or needs to be modified.
- Depict the drilling progress and wellbore in relation to nearby wells to ensure the wellbore does not jeopardize the recovery of any nearby wells.
As additional wellbore data are acquired during the drilling process, they can be incorporated to provide the most current and accurate visualization of drilling progress. When insight from real-time drilling data analysis is incorporated into a 3D subsurface model, engineers gain a detailed level of understanding of drilling progress and conditions. With this continuous assessment of drilling operations, engineers can anticipate potential problems that may impede drilling progress or result in deviation from the intended wellpath. Armed with current, detailed data, drilling engineers can then determine the most sufficient options to mitigate these problems and reach the target zone.
Visualization Is Key To Reducing Targeting Risks
Drilling engineers can leverage the insights available from real-time drilling data analysis with the aid of CoViz 4D. By incorporating drilling data obtained from a WITSML server and visualizing it in context of 3D geologic models, CoViz 4D enables engineers to monitor the drilling process with the aid of advanced 3D visualization. CoViz 4D uses a data registry to easily integrate a wide range of datasets associated with the reservoir development process, uses ISCWSA standard tool models to establish positional uncertainty along the wellpath, and applies powerful visualization techniques to render drill bit and wellbore location.
The ability to visualize and analyze real-time drilling data in context of geologic structures and subsurface conditions can significantly reduce targeting risks.
Missing the target zone by even a few feet can equate to millions in lost revenue. The ability to visualize and analyze real-time drilling data in context of geologic structures and subsurface conditions can significantly reduce targeting risks.