Load Cases

Summary page for load cases available in Oliasoft WellDesign™

Summary

A load case is strictly defined as a set of 3 profiles, internal pressure profile, external pressure profile and a temperature profile. These three profiles constitute a new condition or scenario for a given casing or tubing. When comparing this new condition to the initial conditions , it is possible to calculate the full axial load, related safety factors, and triaxial stress of the new condition.

Note: In this documentation we denote any tubular as casing or tubing. All calculations however encompass any tubular, such as tubings, casings, liners, tie-backs etc.

Terminology

Even though a load case is defined as a set of 3 profiles, the documentation discuss each profile separately. For example, for the load case Displacement to gas, only the internal profile is defined. In the application however, this internal profile must be paired with an appropriate external pressure profile, and a temperature profile.

Types of Load Cases

Generally, the term load cases are categorised in two groups.

Installation load case

Load that occur due to installation of the string, f.ex "run in hole", "overpull" or "pre-cement static load".

Service load case

Load that occur after the string has been installed (cemented or set packers) due to some scenario, f.ex "Displacement to gas", "Tubing leak" or "Casing Evacuation".

Oliasoft WellDesign enable 3 types of defining load cases to be applied to any casing / tubing.

• Predefined pressure and temperature profiles

• Custom profiles (often used custom loads)

• Programmable profiles

Predefined Load Cases

Internal Profiles

Note: Normal dimension denotes which type of differential pressure profile the load case normally has. This is however dependent on which external profile the load case is paired with. Load cases do not necessarily have to be in one dimension throughout the profile.

Profile name	Normal dimension
Displacement to gas	Burst
Drill ahead	Burst
Frac @ shoe / gg above	Burst
Gas Kick Profile	Burst
Gas over mud ratio	Burst
Green cement pressure test	Burst
Lost returns with water	Burst
Pressure test	Burst
Surface Protection (BOP)	Burst
Injection Down Casing	Burst
Casing Evacuation	Collapse
Cementing	Collapse
Lost returns with mud drop	Collapse
WCST	Collapse

External Profiles

Profile Name	Default pairings
Fluid Gradients (Burst)	Displacement to gas Drill ahead (burst) Frac @ shoe with GG above Gas Kick Profile Mud over gas ratio Lost returns with water Pressure test
Fluid Gradients (Collapse)	Casing Evacuation Drill ahead Lost returns with mud drop
Fluid Gradients w/PP (Burst)	None
Fluid Gradients w/PP (Collapse)	None
Minimum formation pore pressure	None
Mud and cement mix water	None
Shoe / mud grad. w/PP	None
Hydrostatic Isolation Depth	WCST
Mud and Cement mix water	Surface Production (BOP)
Mud and Cement slurry	Green cement pressure test Cementing

Temperature Profiles

Profile Name	Profile type
BHC temperature	Static
Geothermal temperature	Static
Production temperature	Static
Simulation temperature*	Transient

Simulated temperatures are thermal profiles calculated by the "temperature simulator". Once such simulations has been performed, the resulting profiles can be used as input in load cases.

Custom Profiles (Custom Loads)

A custom profile is, as opposed to a predefined profile, defined by the user as either a pressure profile per depth or a temperature profile per depth.

A custom pressure profile can constitute an internal profile, external profile or both.

Programmable Profiles

A programmable profile, is similar to a predefined load except that the calculation or algorithm is defined by the user. This is often used where a company has an internal requirement to check a certain scenario which is not covered by the predefined profiles, instead of calculating it manually and entering it as a custom profile.

Programmable load cases is handled by Oliasoft API and can be saved on a company level as a new predefined profile for that company.

Load Cases

Gas KickDisplacement to GasGas Over Mud RatioHydrostatic Isolation DepthLost Returns with Mud DropLost Returns with WaterOverpullRun in HoleTubing Leak