Weight Distribution Between Drill Bit and Reamer
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Solution Overview
Problem
The uneven distribution of weight-on-bit between a pilot drill bit and a reamer device during wellbore drilling leads to undesirable vibrations and inefficiencies when transitioning through different geological formations, as the reamer's lower rate of penetration in harder formations limits the overall drilling rate and causes uneven weight distribution.
Innovation Solution
Configuring the pilot drill bit and reamer device to maintain a predetermined ratio of weight-on-bit distribution, with the reamer device receiving no more than 50% of the total weight, by tailoring cutter exposure, aggressiveness, and depth-of-cut control features to ensure consistent penetration rates through both hard and soft formations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If a reamer device is used to enlarge the wellbore diameter, then the wellbore diameter is increased, but the rate of penetration decreases in harder formations
Solution Approach 1:
The bottom hole assembly is segmented into two distinct functional components: a pilot drill bit for drilling and a reamer device for enlarging. This segmentation allows each component to be optimized for its specific function, with the pilot bit maintaining aggressive penetration capability while the reamer provides controlled enlargement, resolving the contradiction between wellbore diameter and rate of penetration
Solution Approach 2:
The system dynamically adjusts weight-on-bit distribution between the pilot drill bit and reamer device through configurable elements (such as adjustable bearers or variable stiffness connections). This dynamic weight distribution ensures the pilot bit receives sufficient weight to maintain high penetration rates in hard formations while the reamer receives appropriate weight for controlled enlargement, preventing the productivity loss that would occur with static weight distribution
2Productivity
If weight-on-bit is applied to advance the bottom hole assembly, then penetration into formation is achieved, but uneven weight distribution occurs between pilot bit and reamer
Solution Approach 1:
Different portions of the bottom hole assembly are assigned different local qualities in terms of weight-bearing characteristics. The pilot drill bit is configured with higher cutter exposure and aggressiveness to handle harder formations, while the reamer device is configured with lower weight requirements. Configurable weight distribution mechanisms (such as adjustable bearers or variable stiffness connections) ensure each component receives the appropriate local weight quality needed for its specific function, preventing uneven weight distribution and associated vibrations
Solution Approach 2:
The system changes the weight-on-bit parameter dynamically or configurably between the pilot drill bit and reamer device. By adjusting parameters such as cutter exposure, aggressiveness, and depth-of-cut control features, along with configurable weight distribution mechanisms, the system optimizes the weight parameter for each component based on formation conditions, maintaining stable weight distribution and consistent penetration rates
3Area of moving object
If the reamer device contacts uncut formation, then wellbore enlargement is achieved, but vibrations increase due to uneven weight distribution
Solution Approach 1:
The system changes the weight-on-bit parameter and cutter configuration parameters to optimize the interaction between the reamer device and formation. By adjusting cutter exposure, aggressiveness, and depth-of-cut control features, along with configurable weight distribution, the system ensures the reamer contacts the formation with appropriate force to achieve enlargement while minimizing vibrations caused by uneven weight distribution
Solution Approach 2:
The system converts the potential harmful effect of reamer-formation contact (which causes vibrations) into a beneficial controlled process. By using configurable weight distribution mechanisms and optimizing cutter parameters, the reamer's contact with uncut formation is transformed from a vibration-inducing problem into a controlled enlargement process that benefits from the pilot bit's preliminary work while maintaining stable weight distribution
Data Source
AI summary
Methods, systems, and tool assemblies for distributing weight between a bit and a reamer device are disclosed. For example, at least one of the drill bit and the reamer may be configured to selectively distribute a weight-on-bit between the drill bit and the reamer, such as within a predetermined range. Additionally, methods of drilling wellbores may include selectively distributing a weight-on-bit applied to a bottom hole assembly between a drill bit and a reamer of the bottom hole assembly. Also, a reamer may be configured to exhibit a first maximum rate-of-penetration into a relatively hard formation, and a drill bit may be configured to exhibit a second maximum rate-of-penetration into a relatively soft formation that is less than the first maximum rate-of-penetration.