What are the best ways to optimize your casing design for long and horizontal wells?

1 Selecting the right casing size and weight

One of the first steps in casing design is to choose the appropriate casing size and weight for your well objectives and conditions. The casing size and weight affect the wellbore geometry, the drilling fluid properties, the cementing quality, and the completion options. For long and horizontal wells, you may need to use smaller casing sizes and lighter weights to avoid excessive friction, torque, and drag during drilling and running operations. However, you should also consider the minimum acceptable hole size for your reservoir, the expected well pressure and temperature, and the availability of casing materials and equipment.

2 Applying the proper casing strength and safety factors

Another important factor in casing design is to ensure that the casing has enough strength and safety margin to withstand the various loads and stresses that it may encounter during the well lifecycle. These include internal and external pressure, axial tension and compression, bending, buckling, and thermal expansion and contraction. For long and horizontal wells, you may need to apply higher casing strength and safety factors to account for the increased complexity and uncertainty of the wellbore trajectory, the lateral forces and deflections, and the potential for fatigue and wear. You should also use reliable design methods and software tools to calculate the casing loads and stresses and to select the suitable casing grades and connections.

3 Considering the optimal casing setting depth and number of strings

A third aspect of casing design is to determine the optimal casing setting depth and number of strings for your well. The casing setting depth and number of strings affect the wellbore stability, the drilling efficiency, the cementing quality, and the completion flexibility. For long and horizontal wells, you may need to use deeper casing setting depths and more casing strings to isolate the different formations and pressures, to facilitate the directional drilling and horizontal landing, to provide adequate cement coverage and isolation, and to enable the installation of advanced completion systems. However, you should also balance the benefits of deeper and more casing strings with the drawbacks of higher costs, longer rig time, and lower hole size.

4 Evaluating the best casing running and cementing practices

A fourth aspect of casing design is to evaluate the best casing running and cementing practices for your well. The casing running and cementing practices affect the well integrity, the zonal isolation, and the wellbore quality. For long and horizontal wells, you may need to use special casing running and cementing techniques to overcome the challenges of long distances, high angles, narrow clearances, and low annular velocities. Some of these techniques include using centralizers, wipers, and float equipment, applying torque and drag reduction agents, performing reciprocation and rotation, using stage cementing or foam cementing, conducting cement bond logging, and performing pressure testing and remediation.

5 Incorporating the appropriate casing design criteria and standards

A fifth aspect of casing design is to incorporate the appropriate casing design criteria and standards for your well. The casing design criteria and standards provide the guidelines and specifications for the casing selection, design, installation, and testing. For long and horizontal wells, you may need to follow the specific casing design criteria and standards that are applicable to your well location, type, and purpose. These may include the local regulations, the industry best practices, the operator policies, and the project objectives. You should also update and document your casing design criteria and standards as the well conditions and requirements change.

6 Optimizing your casing design for long and horizontal wells

Optimizing your casing design for long and horizontal wells can help you achieve your well goals and overcome your well challenges. By following the best ways to optimize your casing design, such as selecting the right casing size and weight, applying the proper casing strength and safety factors, considering the optimal casing setting depth and number of strings, evaluating the best casing running and cementing practices, and incorporating the appropriate casing design criteria and standards, you can improve your well performance, safety, and profitability.

7 Here’s what else to consider

This is a space to share examples, stories, or insights that don’t fit into any of the previous sections. What else would you like to add?