ESP Pump Stage Sequential Engagement for Shaft Torque Control
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Solution Overview
Problem
Conventional electric submersible pump (ESP) systems face issues with solid precipitation and deposition, leading to increased trips, motor overload, and potential shaft damage due to scale and corrosion buildup, especially when using direct on-line starters, which can result in shaft breakage and failure to restart.
Innovation Solution
The implementation of a transmission mechanism between pump stages in ESP systems that allows for sequential engagement of pump sections, reducing system inertia at startup and minimizing the risk of shaft damage by enabling controlled rotation and torque distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If all pump stages are on the same shaft and start rotating at the same time, then the multi-stage system can generate high total head, but the system inertia is high and shaft damage risk increases due to solid buildup
Solution Approach 1:
The pump shaft is divided into multiple independent shaft segments (first shaft segment, second shaft segment, third shaft segment) that can rotate independently. Each shaft segment connects to corresponding pump stages through separate bearings, allowing the pump stages to be segmented into groups that can be engaged sequentially rather than all at once. This segmentation reduces the moment of inertia for each startup event while maintaining the ability to generate high total head when all stages operate.
Solution Approach 2:
The system engages pump stages in a predetermined sequence during startup. The first shaft segment and its associated pump stages are engaged first, allowing the system to gradually build up operation. Subsequent shaft segments are engaged after the initial segment is already rotating, which reduces the overall system inertia at each engagement moment and prevents shaft breakage from excessive startup torque.
2Speed
If direct on-line starter is used to start ESP, then the system can start quickly, but shaft breakage can occur due to high torque applied
Solution Approach 1:
The shaft system is segmented into multiple independently supported shaft segments, each capable of being engaged separately. This allows the startup process to be divided into multiple smaller torque applications rather than one large torque application, maintaining quick startup while protecting shaft strength.
Solution Approach 2:
The system transitions from a static engagement state to a dynamic sequential engagement state. During startup, shaft segments are engaged in sequence rather than all at once, creating a dynamic startup process that adapts the torque application to the system's current state. This dynamic approach allows fast startup while distributing torque loads to protect shaft strength.
3Reliability
If sequential engagement of pump sections is implemented, then shaft damage risk is reduced, but device complexity increases due to transmission mechanisms
Solution Approach 1:
The pump system is segmented into multiple independently supportable sections (first pump stage, second pump stage, third pump stage) with corresponding shaft segments. Each segment has its own bearing support structure, allowing them to be engaged independently through simple coupling mechanisms rather than requiring complex transmission systems.
Solution Approach 2:
Bearings serve as intermediary elements that provide rotational support for each shaft segment independently. The first bearings support the first shaft segment, the second bearings support the second shaft segment, and the third bearings support the third shaft segment. These bearing intermediaries simplify the connection between shaft segments and pump stages, reducing overall device complexity while enabling sequential engagement for improved reliability.
Data Source
AI summary
A method for providing artificial lift with an electric submersible pump system includes providing an electric submersible pump system having a motor, a pump assembly, a seal assembly, and a shaft assembly extending along a central axis from the motor to the pump assembly. The pump assembly includes two or more pump sections and a coupling with a transmission mechanism is located between the two or more pump sections. The motor rotates a motor shaft segment of the shaft assembly that is in engagement with a first pump section and starts the first pump section. One of the transmission mechanisms is moved from a disengaged position to an engaged position where the coupling conveys the rotation of the motor shaft segment to the adjacent shaft segment and starts another of the two or more pump sections.