Life Cycle of Oil & Gas Wells - from Drilling to Completion

Summary

This video script outlines the process of drilling and completing a well, starting with drilling the surface section and installing casing for environmental protection. The script details the selection of casing based on various factors such as hole size, pressure, and material properties. It continues by explaining cementing, perforation, and evaluating the pay zone, followed by the completion phase, where production is initiated. The process concludes with installing a Christmas tree for production and the eventual plugging and abandonment of the well once production decreases.

Takeaways

• 😀 The surface section of the well is drilled, and the drill pipe is pulled out to lay the casing for environmental and safety reasons.
• 😀 The casing string is made of several joints, chosen based on its size, thickness, length, weight, and steel grade.
• 😀 The grade of casing is selected based on variables such as hole size, drilled hole irregularities, expected pressure, and H2S content.
• 😀 The casing is suspended by hangers and secured to the formation with cement, ensuring a seal for further operations.
• 😀 Cementing requires sufficient curing time to ensure a proper seal between the casing and formation.
• 😀 After cement curing, drilling continues through the cement and formation to reach the desired depth, known as total depth (TD).
• 😀 Logging tools are often used to evaluate the formation and assess the economic feasibility of the pay zone during drilling.
• 😀 The well completion process involves inserting a casing string to prevent the borehole wall from collapsing and to allow further operations.
• 😀 Cement bonding between the casing and formation is evaluated using a cement evaluation tool to ensure proper integrity.
• 😀 A perforating gun is lowered into the well to create a path for the hydrocarbons to flow from the reservoir into the wellbore.
• 😀 A production string is installed with a packer to direct hydrocarbons through the production tubing to the surface.
• 😀 The wellhead equipment, often referred to as the Christmas tree, is installed at the top of the well, and production begins once the well is completed.

Q & A

What is the purpose of laying casing in the well?

Laying casing in the well is done for environmental reasons, to hydraulically seal the formation layers containing aquifers from the flowing hydrocarbons. This helps prevent contamination and ensures that the formation is isolated during drilling.

What factors determine the selection of casing grade?

The selection of casing grade depends on various factors, including the size of the hole, the roughness of the drilled hole, expected pressure from flowing hydrocarbons, the H2S content, and economic considerations.

What does the process of cementing the casing achieve?

Cementing the casing ensures that a proper seal is created between the casing and the formation, which isolates the aquifers and secures the casing in place for further operations.

What is the total depth (TD) of a well?

Total depth (TD) is the depth at which drilling stops, typically where the pay zone is anticipated to be, and the well is considered completed or ready for further evaluations.

What is the purpose of logging while drilling (LWD) tools?

Logging while drilling tools are used to evaluate the formation during drilling, helping assess the economic feasibility of the well by measuring properties of the drilled zone in real-time.

How is formation evaluation done after drilling to assess economic viability?

Formation evaluation is typically done by lowering wireline logging tools into the well. These tools gather data through various sensors to assess the presence and properties of the anticipated pay zone, determining the economic viability of production.

What is the role of cement evaluation wireline tools?

Cement evaluation wireline tools are used to assess the bond between the cement, casing, and formation. If the cement bond is inadequate, remedial operations are performed to ensure proper sealing.

What is the purpose of a perforating gun in well completion?

The perforating gun is used to create a pathway through the formation, cement, and casing, allowing hydrocarbons to flow into the well's production tubing. This is a crucial step in well completion after evaluating the pay zone.

What is tubing conveyed perforating (TCP), and when is it used?

Tubing conveyed perforating (TCP) is a method used to deploy long and heavy perforating gun strings into the well. It is typically used when short and light gun strings cannot be used due to weight and depth considerations.

What is the function of the production packer in a well?

The production packer is installed near the bottom of the production string above the perforations. It ensures that hydrocarbons flow only through the production tubing, preventing unwanted flow outside of the designated production path.