Basic Well Completion, Perforation, Stimulation & Sand Control

Summary

This script outlines the complex process of well completion in oil and gas production. It details the steps from running the final casing string and cementing to selective perforation and stimulation techniques like acidizing and hydraulic fracturing. It also touches on sand control methods, emphasizing the uniqueness of each completion project and the importance of paperwork in the industry.

Takeaways

• 🛠️ The script describes the process of completing a well in the oil and gas industry, starting with running the final string of casing and cementing it in place.
• 💥 After cementing, selective perforation of the casing is performed using shaped jet charges to allow formation fluids to flow into the wellbore.
• 📐 Alternative completion methods such as liner completion and open hole completion are mentioned, each with its own setup and purpose.
• 🚧 Stage cementing may be necessary in deep wells, where cement is pumped around the casing shoe and then forced into the upper portion of the annular space.
• 🧹 It is crucial to ensure the inside of the production casing is clean and that the cement forms a competent seal to prevent communication between formations.
• 🔍 An acoustic cement bond log can be run inside the casing to verify the quality of the cement job and ensure proper sealing.
• 🚨 If the cement job is poor, a squeeze job may be required to inject cement into the void space behind the casing.
• 🔄 The script also discusses the use of a correlation log to determine where to perforate or set downhole equipment by matching gamma ray curves from earlier logs.
• 💡 Stimulation techniques such as acidizing and hydraulic fracturing are mentioned as methods to increase the flow passages in the rock formation.
• 🏜️ In some areas, stimulation is not needed as formations are naturally unconsolidated and can produce without additional measures.
• 🏗️ Sand control methods are important to prevent formation sand from entering the well, using techniques like gravel packing or epoxy resin consolidation.
• 📋 The importance of paperwork and the uniqueness of each drilling and completion program is emphasized, noting that the described procedures are typical but not universal.

Q & A

What is the final step in the completion of a well as described in the script?

The final step in the completion of a well is running the final string of casing, which involves cementing the production casing in place and selectively perforating it with shape jet charges to allow formation fluids to flow into the wellbore.

What are the two alternative basic completion methods mentioned in the script?

The two alternative basic completion methods mentioned are liner completion and open hole completion.

What is a liner completion in the context of well drilling?

In a liner completion, the production casing is set above the producing zone, and another length of small diameter casing is hung from near the bottom of the production string down inside the wellbore. This liner may be slotted and not cemented, or it may be regular casing which is cemented and then perforated.

What is an open hole completion and how does it differ from a liner completion?

An open hole completion is similar to a liner completion, but no liner is run. The productive zone is not protected or inhibited by any casing, and it remains as an open hole after the completion process.

What is the purpose of running an acoustic cement bond log inside the casing?

The purpose of running an acoustic cement bond log inside the casing is to give an indication of the quality of the cement job and to ensure that the cement forms a competent seal between the casing and the borehole for the entire openhole interval.

What is the role of the correlation log in the completion process?

The correlation log, which has a gamma ray track, is used to correlate with earlier logs run in the open hole evaluation. It helps in identifying the position of each casing joint and coupling collars, and is used to determine where to perforate or set downhole equipment.

What is the significance of ensuring a clean inside of the production casing?

Ensuring a clean inside of the production casing is important to prevent any debris that could affect the well's performance and to ensure the proper functioning of the well's surface flow control equipment.

What is meant by 'underbalanced perforating' and why is it used?

Underbalanced perforating is done with an underbalanced wellbore, allowing immediate flow when the perforations are created. It relies on the sudden force of the flowing hydrocarbons to flush debris from the perforations and ensure that none remain plugged, causing lower productivity.

What are the two common techniques for well stimulation mentioned in the script?

The two common techniques for well stimulation mentioned are acidizing and hydraulic fracturing.

How does acidizing work in well stimulation?

Acidizing involves pumping an acid solution, usually hydrochloric acid, down the well and into the pore spaces of the rock formation. The acid partially dissolves the materials found between the grains of the rock or a portion of the rock itself, increasing the size of the flow passages.

What is hydraulic fracturing and how does it create flow passages in a rock?

Hydraulic fracturing is a stimulation technique used to create flow passages in a rock where none or few exist. A fluid is pumped down the wellbore at pressure sufficient to cause the rock to split apart, usually vertically. As the fracturing fluid is pumped into the fracture, it extends further from the wellbore, and a proppant material, usually sand, is carried along to prop open the crack and prevent it from closing up completely, creating a high permeability pipeline to the wellbore.

What are the two approaches for sand control in well completions?

The two approaches for sand control in well completions are using a metal or sand grain barrier which screens out the formation sand but does not inhibit fluid flow into the wellbore, or using an epoxy resin which is injected into the rock and hardens to form a consolidating binder for the formation sand grains.