Piston-Diaphragm Pump Isolates Piston from Abrasive Drilling Mud
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Solution Overview
Problem
Existing mud pumps with positive displacement piston designs have short service lives due to wear and tear from abrasive drilling mud, requiring frequent replacement of pistons and cylinders.
Innovation Solution
A piston-diaphragm pump design that separates the piston and cylinder from the drilling mud using a rubberized flexible diaphragm, reducing mechanical and erosive wear and extending the service life of pump components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a positive displacement piston pump is used to pump drilling mud, then the pump can achieve high pressure and flowrate, but the piston and cylinder wear out quickly due to abrasive drilling mud
Solution Approach 1:
A flexible diaphragm is introduced as an intermediary component between the piston and the drilling mud. The diaphragm separates the hydraulic fluid chamber (containing the piston) from the drilling mud chamber, allowing the piston to pump the diaphragm which in turn displaces the drilling mud. This intermediary prevents direct contact between the abrasive drilling mud and the piston, eliminating wear on the piston and cylinder while maintaining the pumping function.
Solution Approach 2:
The patent employs a flexible diaphragm made of elastomeric material as a thin film separator. This diaphragm flexes during the pumping cycle - being pushed inward by the piston during the power stroke and returning to its original shape during the suction stroke - thereby transmitting the mechanical motion from the piston to the drilling mud without direct contact. The flexible nature of this thin film allows it to accommodate pressure changes while protecting the piston from abrasive damage.
2Reliability
If a diaphragm is introduced to separate the piston from drilling mud, then wear is reduced, but the device complexity increases
Solution Approach 1:
The diaphragm is designed as a simple, single-piece elastomeric membrane that integrates multiple functions: sealing between chambers, transmitting mechanical motion, and protecting the piston. Its flexibility allows it to conform to pressure changes and maintain sealing without requiring complex mechanical components, thereby minimizing the increase in device complexity while achieving wear reduction.
Solution Approach 2:
The diaphragm serves multiple functions simultaneously: it acts as a separator between hydraulic fluid and drilling mud, a flexible coupling that transmits motion from piston to mud, a seal maintaining pressure differentials, and a protective barrier against abrasive wear. By consolidating these functions into a single component, the design avoids the need for multiple separate parts, thereby limiting the increase in overall device complexity.
3Reliability
If the piston operates in lubricating oil instead of drilling mud, then wear is minimized, but the ability to directly displace drilling fluid is lost
Solution Approach 1:
The diaphragm acts as a mediator that couples the piston's motion in the lubricating oil chamber to the drilling mud in the other chamber. When the piston moves in the lubricating oil, it directly pushes the diaphragm, which in turn displaces the drilling mud with the same volume and pressure characteristics. This intermediary mechanism preserves the productivity of direct displacement while allowing the piston to operate in the benign lubricating oil environment.
Solution Approach 2:
The system uses hydraulic principles where the piston moving in lubricating oil creates pressure changes that are transmitted through the flexible diaphragm to the drilling mud. The incompressibility of both hydraulic fluids allows for efficient transmission of force and displacement, maintaining the productivity equivalent to direct piston-mud contact while protecting the piston through the diaphragm barrier.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The piston-diaphragm pump design achieves the same displacement, pressure, and flowrate as traditional piston pumps while significantly extending the service life of pistons and liners to several years, reducing maintenance downtime and costs.
Implementation Method 1
a rubberized flexible diaphragm which separates the piston and cylinder from the mud slurry. When the piston moves to the bottom of its stroke, the diaphragm pulls back into a concave shape corresponding to the same volume displacement. When the piston moves to the top of its stroke, the diaphragm pushes out into a convex shape
Data Source
AI summary
A drill rig may include a motor connected to a piston-diaphragm pump configured to: apply a force to a fluid in a cylinder of the piston-diaphragm pump by moving a piston in the cylinder, the fluid filling a void inside the cylinder between a head of the piston and one side of a diaphragm; transfer the force from the fluid across the diaphragm to a drilling mud by flexing the diaphragm, where the drilling mud is separated from the first fluid; and cause a flowrate of the drilling mud through a value connected to the cylinder via a high-pressure piping system into the borehole. The drill rig may direct the mud through a kelly and a pipe to a bottom of the wellbore, force the mud through nozzles located near a bit, rotate the bit, and returning the mud through an annulus to the surface.