Borehole pressure required to reach tensile failure depends on: tensile strength of the rock; state of stress in the formation; orientation of the wellbore with respect to the state of stress; shape of the wellbore cross-section; wellbore fluid penetration into the rock; chemical interaction between the wellbore fluids and the rock. 1. State of stress … Basic aspects of rock mechanics

In the detailed design phase, the casing designer determines the material grade and casing wall thickness for each section of the casing scheme selected, which will allow it to withstand all realistically expected loads throughout the life of the well. Selection of relevant load cases Before design calculations can be performed for a given casing … Detailed Design and Analysis

This article describes the uniaxial collapse, burst, axial and compression design factors, and the triaxial design factor, recommended for use, together with a brief overview of the considerations which led to the choice of the generally accepted values. Each uniaxial design factor is defined as the minimum ratio required between the corresponding casing strength tabulated … Casing design factors

Procedures for leak-off and limit tests. Leak-off and Limit tests are carried out during the drilling phase of the well. The BOP is closed around the drillpipe, and the well is slowly pressured up, using mud. At the first sign of fluid leak-off into the formation the pumping is stopped. Leak-off tests are carried out … Procedures for leak-off and limit tests (LOT, LT, FIT)

The objective of the casing design is to define a set of casing strings (casing scheme), capable of withstanding a variety of external and internal pressures, thermal loads and loads related to the self-weight of the casing. These casing strings are subjected to time-dependent corrosion, wear and possibly fatigue, which downrate their resistance to these … Casing design considerations

The output of this process is a preliminary well configuration specifying the minimum casing diameter and the minimum casing-shoe setting depth for all strings. This serves as input for the detailed design phase. The casing diameter is mainly determined by the availability of downhole drilling equipment, logging tools and production requirements. The casing-shoe setting depth … Casing scheme selection

Early collection of all the relevant data is essential and it should be done by a multidisciplinary team. Considerable effort is required from the Petroleum Engineering and Operations departments when planning, designing and drilling/completing a well. Because of the high costs, the data set used for casing design must be as complete as possible right … Casing Design parameters

Expanding latch hanger mechanisms should recock when the string is picked up (if accidentally engaged in the BOP’s etc.). All liner tools should have OD profiles that do not catch or snag on the inside of conventional BOP’s, wellheads or casing connections.  The flowby area on all hangers should be maximised. Either on landed position … Liner hanger selection – Design criteria