Horizontal PMM Drive for PCP Wellhead Access
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Solution Overview
Problem
Conventional drive units for progressive cavity pumps obstruct access to the wellhead, preventing the inclusion of a second string in the wellbore.
Innovation Solution
A progressive cavity pump system utilizing a permanent magnetic motor (PMM) with a horizontally oriented drive shaft that is not coaxial with the rod string axis, allowing for a second string to be present in the wellbore by positioning the PMM away from the wellhead, and incorporating a gearbox and bearing assembly to transfer rotational power efficiently.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a conventional drive unit is used to drive the rod string, then the rod string can be rotated to drive the PCP rotor, but the drive unit obstructs access to the wellhead preventing a second string from being present in the wellbore
Solution Approach 1:
The PMM is oriented horizontally rather than vertically, changing the spatial dimension of motor placement. This horizontal orientation positions the motor perpendicular to the wellhead access path, allowing a second string to be installed through the wellhead without obstruction from the drive unit
Solution Approach 2:
Instead of the conventional vertical orientation where the motor sits above the wellhead, the PMM is inverted to a horizontal orientation with the drive shaft extending laterally. This inversion relocates the motor away from the wellhead centerline, clearing the path for second string access
2Ease of operation
If a permanent magnetic motor with horizontal orientation is used, then access to the wellhead is improved allowing a second string, but the motor orientation requires a gearbox and bearing assembly to transfer rotational power
Solution Approach 1:
A gearbox is introduced as an intermediary component between the horizontally oriented PMM and the rod string. The gearbox contains bearing assemblies that mediate the power transfer, converting the horizontal rotation of the PMM drive shaft into vertical rotation of the rod string while managing the mechanical interface between these two orientations
3Use of energy by moving object
If conventional motors are used, then the drive unit structure is simpler, but power consumption and maintenance needs are higher
Solution Approach 1:
The PMM operates with modified operational parameters including variable speed control and adjusted torque characteristics optimized for PCP applications. These parameter changes enable the motor to achieve superior energy efficiency and reduced maintenance needs compared to conventional motors, despite the added complexity of horizontal orientation and gearbox integration
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
Enables greater access to the wellhead for a second string while reducing power consumption, maintenance needs, and operational costs, with improved torque control and reduced noise and vibration.
Implementation Method 1
a permanent magnetic motor configured to drive rotation of the rod string, wherein the PMM is oriented such that a drive shaft of the PMM rotates about a drive shaft axis that is not coaxial with the rod string axis
Implementation Method 2
The first gear is rotationally connected to the rotary shaft, wherein rotation of the rotary shaft causes the first gear to rotate about the first axis. The second gear is engaged with the first gear and rotationally connected to the tubular shaft, wherein rotation of the first gear causes the second gear and the tubular shaft to rotate about the second axis
Implementation Method 3
The first bearing assembly comprises a first bearing and a second bearing, wherein the rotary shaft is disposed within first bearing and the second bearing. The second bearing assembly comprises a thrust bearing, a first radial bearing, and a second radial bearing, wherein the tubular shaft is disposed within the thrust bearing, first radial bearing, and second radial bearing
Data Source
AI summary
A progressive cavity pump system including a pump string disposed in a wellbore. The pump string includes a progressive cavity pump and a rod string, wherein the rod string is rotatable about a rod string axis to rotate a rotor of the progressive cavity pump. The progressive cavity pump system includes a permanent magnetic motor (“PMM”) configured to drive the rotation of the rod string. The PMM is oriented such that a drive shaft of the PMM rotates about a drive shaft axis that is not coaxial with the rod string axis.