Introduction of Fishing Tools（3）

Falling object fishing tool

1. Fishing cup while drilling

1) Use

The fishing cup is mainly used to catch the heavy drilling cuttings or metal debris that cannot be taken out of the wellbore by normal mud circulation during drilling. It plays an important role in keeping the bottom of the well clean, increasing the life of the bottom of the bit, and reducing and preventing accidental damage to the bit.

2) Structure

The salvage cup is composed of a mandrel, a centering block and a cup tube. The same size and specifications of the salvage cup are available: standard (S type), long (L type) and extra long (EX type) models.

3) Working principle

Because the outer diameter of the outer cylinder of the salvage cup is large, and the annular gap between the well is small, and the diameter of the bottom mandrel at the mouth of the cup is small, and the annular gap is large, the flow rate of the drilling fluid at the mouth of the cup drops sharply, forming a vortex. Its carrying capacity is also greatly weakened, so that the heavier debris in the drilling fluid falls into the cup and is removed with the drilling to achieve the purpose of cleaning the bottom of the well.

2.Reverse cycle fishing basket

The reverse circulation fishing basket is mainly used for downhole fishing tools such as drill cones, teeth, hand tools and broken iron. During salvage operations, it can cause local reverse circulation at the bottom of the well.

1) Structure

The outer part of the reverse circulation fishing basket is composed of upper joints, barrels, shoe mills, etc., and the internal parts are composed of valve cups, steel balls, valve seats, and fishing claw plate assembly. There is a recyclable space between the outer cylinder and the inner cylinder. The water eye on the outer cylinder is 45 degrees upwards and it is not in the middle of the two cylinders, but it communicates with the inner cavity of the inner cylinder. The lower milling shoe teeth are welded with tungsten carbide particles, which have high wear resistance and easy repair. The valve cup is used to guide the steel ball to fall correctly into the valve seat. In order to form a reverse cycle.

2) Working principle

The reverse circulation salvage basket circulates through the valve seat when the ball has not been thrown after going down the well, and then returns from the inside of the cylinder through milling shoes. This is a positive cycle. After casting the steel ball, when the steel ball falls on the valve seat, the mud is forced to divert into the two cylinder The middle of the double layer flows out from the water eye at high speed, and after being milled into the inner cavity of the inner cylinder through the milling shoes, the upper water eye returns to the space between the outer cylinder and the wall of the well, thus achieving the purpose of post circulation.

3.Reverse circulation strong magnetic salvage

Reverse circulation strong magnetic salvage tool is a tool for salvaging small objects falling downhole in petroleum and geological exploration work. It uses its own permanent magnet to magnetize the small objects such as rollers, large jaws and other objects to magnetize them, thereby effectively salvaging small objects and purifying the bottom of the well. Reverse circulation strong magnetic salvage device consists of upper joint, centering sleeve, permanent magnetic core, steel sleeve, steel ball and flat bottom shoes.