In the oil and gas industry, equipment failures are not uncommon, especially during extended downhole operations. One such common issue involves the breaking or dropping of sucker rods into the wellbore. When this happens, a specific fishing tool known as the sucker rod overshot is deployed to recover the lost components and restore well functionality.
What Is a Sucker Rod Fishing Overshot
A sucker rod fishing overshot is a mechanical tool used to retrieve broken or dropped sucker rods from the well. It is typically run on a workover rig during fishing operations and is designed to latch onto the head or body of the stuck rod and extract it from the wellbore.
This tool is part of a larger category of oilfield tools known as fishing tools, which are used to recover any object or debris that is not supposed to be in the well—often referred to as “fish.”
How It Works
The overshot operates on a simple but effective mechanical principle:
- It is lowered into the wellbore on a tubing or sucker rod string until it reaches the top of the stuck or broken rod.
- The overshot then slides over the rod, and an internal grapple or slip mechanism engages the rod’s outer surface.
- Once the grapple is set, the overshot is pulled upward, retrieving the stuck sucker rod to the surface.
There are various types of grapples used inside the overshot, such as spiral grapples, basket grapples, or wedge-type slips, depending on the well conditions and the size and shape of the fish.
Applications and Importance
- Well Workover Operations: Commonly used during well servicing or maintenance when a sucker rod part has broken.
- Minimizing Downtime: Prevents long delays by retrieving lost components instead of drilling a new well.
- Cost-effective Solution: Saves money by allowing recovery instead of replacement.
Conclusion
The sucker rod fishing overshot is a vital tool in oilfield workover and fishing operations, offering a practical and efficient solution to a common challenge in rod-pumped wells. Understanding its function and use is essential for any operator or technician involved in drilling and well servicing.