| dc.description.abstract | Design and planning in drilling a well are a key for successful before to execute drilling operation. A good understanding of wellbore stability, design mud, casing, cementing, BHA & drillstring, drilling bit, hole cleaning & hydraulic are an important process in well planning. Good design and planning can keep drilling activity on track based on schedule and it can avoid non-productive time during drilling.
By knowing the rock mechanics properties is important in the drilling design. Many problems happen during drilling relate to rock mechanics. One of the problem during drilling relates to rock mechanics is wellbore instability. Before drilling, rock in equilibrium condition but after drilling, there is a disturbance in the rock formation and it changes stress distribution. Knowing the insitu stresses (vertical stress, maximum horizontal stress, minimum horizontal stress) and stresses around the borehole wall (radial stress, axial stress and tangential stress) are important. With knowing these parameters, wellbore collapse caused by shear stress can be avoided. In this thesis will analyze the sensitivity of the failure criteria with respect to horizontal stress anisotropy and depth, in order to evaluate which failure criteria to recommend under which stress conditions. Mohr-Coulomb, Modified Lade and Stassi d' Alia models will be used to figure out the failure criteria. The result of these models is used to estimate critical mud weight to prevent wellbore collapse.
This study also will analyze drilling optimization through casing design, hole cleaning and hydraulic design, drillstring and bottom hole assembly (BHA) design. Landmark drilling software is used to design drilling optimization. With a good well design, it is expected that it can manage drilling on the track based on budget and it can mitigate problems during drilling.
Keywords:
Pore pressure, fracture pressure, insitu stress, rock mechanics, collapse pressure formation, casing design, cutting transport & hydraulic methods | nb_NO |
