It is the most expensive error made by drilling operators when drilling horizontally, which typically occurs immediately prior to realizing that the operator is making one. By the time a drill bit encounters some change in the formation, options for correcting errors are limited, and the cost of correction is higher.
Conventional visibility will no longer suffice
There is now another question for drilling operators to consider with respect to drilling with subsurface knowledge: What would happen if we could gain enough subsurface knowledge early in the process so that it could influence the end result?
Horizontal wells of today typically run for many miles through thinly layered reservoirs. Even small deviations in geology can lead to lost production or wellbore instabilities. The traditional approaches using resistivity measurements and mapping reservoir tools provide insights into conditions around and behind the drill bit. However, these methods leave operators reacting to changes in their formations once those changes are encountered.
The reactive nature of this approach creates problems for operators who are attempting to drill longer wells and faster because small discrepancies can quickly compound into larger ones; additionally, making corrections to direction adds time, risk, and cost. Consequently, operators have been looking for ways to visualize areas outside the immediate path of the drill bit and not simply refine what has already happened.
Halliburton’s EarthStar®3DX technology was developed to meet those needs
EarthStar® 3DX is the industry’s first three-dimensional (horizontal) look-ahead resistivity service. It provides operators with real-time geological insight up to 50 feet in front of the drill bit. Using this ability to look ahead, operators can identify changes in their formations before they encounter them. They do not react to changes in the formation until after they have occurred.
The heart of the system is an ultra-deep resistivity sensor located near the drill bit that detects changes in resistivity up to 50 feet away from the drill bit. Operators use this sensor data to create a map of geological variations ahead of the drilling operation. These maps allow operators to proactively adjust their drilling paths to maintain contact with the reservoir and minimize unplanned exits or excessive corrections.
There is a significant difference between guiding a well path based upon anticipation versus reacting to events as they occur.
Predictive guidance reduces instability issues
Drilling parameters can also be adjusted in advance of reaching less favorable geologic formations. Drilling parameters such as mud weight can be optimized prior to encountering unfavorable geologic formations, which minimizes the potential for unstable wellbores or mud-weight-related surprises. Halliburton emphasizes that early detection and adjustment of drilling parameters reduce instability challenges and support safe operations as well as improve overall recovery results.
Additionally, the predictability associated with anticipated formation changes enables drilling teams to maintain operational momentum while ensuring that they operate safely and efficiently. In addition, predictive guidance transforms geosteering from corrective steering to directional confidence.
For increasing numbers of complex wells, look-ahead resistivity increases in value
The advantage of acquiring resistivity data ahead of the drill bit is amplified as drilling lengths increase and geologies become more complex. For example, in unconventional plays, multiple thin reservoirs or stacked reservoirs require extremely accurate control of trajectory throughout long distances. EarthStar® 3DX addresses this challenge by expanding an operator’s spatial awareness of the reservoir during the drilling operation.
Halliburton describes EarthStar® 3DX as a component of an integrated reservoir mapping program that helps maximize asset value by providing a better understanding of the subsurface. Unlike other systems that add complexity to drilling workflows, EarthStar® 3DX is intended to simplify decision-making by reducing uncertainty. As wells continue to evolve, both the quality and timeliness of the information acquired during drilling operations will become equally critical factors.
