What is a whipstock used for?

What is a whipstock used for?

Whipstocks are often used to sidetrack the well out of casing (Figure 5). Instead of a drill bit, a mill is used that can cut metal. In this application, the whipstock is left in place to guide tools through the cut in the casing. The drillstring will bend to allow the bottomhole assembly to go around the curved hole.

What is a sidetracked well?

Sidetracking is the term used for drilling a directional hole to bypass an obstruction in the well that cannot be removed or damage to the well, such as collapsed casing that cannot be repaired. To sidetrack, a hole (window) is made in the casing above the obstruction.

What is time drilling?

Time drilling is a process requiring an extremely low rate of penetration—sometimes less than 1 m/h [3 ft/h].

What is a wellbore?

A wellbore is a hole that is drilled to aid in the exploration and recovery of natural resources, including oil, gas, or water. A wellbore is the actual hole that forms the well. A wellbore can be encased by materials such as steel and cement, or it may be uncased.

What is a sidetrack in oil and gas?

Sidetracking is the drilling of a new lateral from an existing well that has poor or no productivity due to mechanical damage to the well or depleted hydrocarbons at that particular site.

What is the difference between borehole and wellbore?

Borehole is often used as a synonym for wellbores, though sometimes the borehole refers to the open diameter of the hole itself, whereas the wellbore is the hole including the casing between the opening and the rock or earth walls on the outside.

How is oil well drilled?

The well is created by drilling a hole 12 cm to 1 meter (5 in to 40 in) in diameter into the earth with a drilling rig that rotates a drill string with a bit attached. After the hole is drilled, sections of steel pipe (casing), slightly smaller in diameter than the borehole, are placed in the hole.

What is multilateral drilling?

A multilateral well is a well with two or more laterals (horizontal, vertical, or deviated) drilled from a main mother well. This allows one well to produce from several reservoirs. Multilateral wells are suitable for complex geology where drilling more new wells to penetrate to those reservoirs is not economical.

Are boreholes and wells the same?

How we define the difference is: Typically a borehole is drilled by machine and is relatively small in diameter. A well is usually sunk by hand and is relatively large in diameter.

Which is better borehole or well?

There is no difference between well, hole and borehole in the sense of the words. A well is a man-made hole deeper than the water table. A borehole is a narrow shaft bored in the ground, either vertically or horizontally.

How do shockwaves find oil?

In the petroleum industry, the most common and effective method of obtaining a clear picture of the Earth’s subsurface is the seismic method. Shock waves set off at the surface penetrate the earth like sonar and the returning echo can be used to tell what is below.

What is a Whipstock used for?

The whipstock is a steel ramp shaped device which deflects the bit off the cement plug. Two types are popular. One is called a permanent whipstock because it is cemented and left in the hole. The other is called a retrievable because after deflecting the bit off the cement plug it is pulled from the hole.

Should Drillers use openhole cement plugs or whipstocks for sidetracking?

Historically, drillers have relied on openhole cement plugs or cased hole whipstocks reducing the time required to initiate cased hole sidetracks. 16 Oilfield Review Whipstock Options for Sidetracking Historically, drillers have relied on openhole cement plugs or cased hole whipstocks for sidetracking wells.

How can Whipstock and mill design reduce the time for cased hole sidetracks?

By incorporating an innovative downhole anchor with a whipstock assembly, drillers can set whipstocks in open holes without concern for cement plug integrity. Advances in whipstock and mill design are also significantly reducing the time required to initiate cased hole sidetracks.

What is the difference between retrievable and permanent Whipstock?

Two types are popular. One is called a permanent whipstock because it is cemented and left in the hole. The other is called a retrievable because after deflecting the bit off the cement plug it is pulled from the hole. The basic problems which often occur are similar for both types.