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Experimental And Modeling Study Of The Effects Of Sealing Structures In Lost Circulation Prevention And Remediation, Mingzheng Yang

LSU Doctoral Dissertations

Drilling fluid lost circulation leads to non-productive time and increases the overall well cost. In general, wellbore strengthening and lost circulation control are achieved by creating effective sealing structures to inhibit fluid flow through loss conduits such as formation fractures. This research aims at better understanding the effects of sealing structures in fluid loss prevention and remediation, and providing useful references to effectively establishing filtercakes on the wellbore and plugs in the fracture.

Recent research on wellbore strengthening disclosed the critical role of filtercake in sealing microfractures during the initial stages of fracture initiation and propagation. The performance of a …

Fluid-Driven Fracture Initiation From Oil And Gas Wells Considering Lifetime Stresses, Andreas Michael

LSU Doctoral Dissertations

Fluid-driven fracture initiation from oil and gas wells is examined in detail. The dissertation covers three subtopics: drilling, completion (stimulations), and post-blowout capping-induced fracture initiation.

Drilling-induced tensile fractures (DITFs) are located in an azimuth orthogonal to wellbore breakouts and are observed from image logs obtained during drilling operations. Fully analytical criteria for the orientation of DITFs initiating from wells in porous, permeable media are derived considering fluid infiltration from a pressurized wellbore. DITF orientation (longitudinal or transverse-to-the-wellbore) is used to constrain the magnitude of the local maximum horizontal principal stress. The range of the possible stress states is indicated on …

Analytical Modeling And Diagnosis Of Penetration Rate Performance Of Pdc Bits, Reza Rahmani

LSU Doctoral Dissertations

The high cost of drilling deep (15000+ ft) wells, due to slow rate of penetration (ROP) at depth, has severely limited the utilization and economic significance of deep hydrocarbon resources. The overall objective of this study was to obtain a better understanding of the major cause(s) of slow ROP in deep drilling. An analysis of field data demonstrated the impact of the problem and identified shale and limestone as the primary lithologies where slow ROP occurs at depth. Previous researchers have concluded that interactions between rock, drilling fluid, cuttings, and the bit control ROP. More specifically, several researchers have concluded …

An Experimental And Computational Investigation Of Rotating Flexible Shaft System Dynamics In Rotary Drilling Assemblies For Down Hole Drilling Vibration Mitigation, Richard Duff

LSU Doctoral Dissertations

Rotary drilling system vibration has long been associated with damaging the bit, the bottom hole assembly (BHA) and drill string. Vibration has been traditionally measured in the bottom hole assembly, and been closely associated with the resonant behaviors.

This research study proposes an improved physical laboratory model to explore the dynamic behaviors associated with vibration. This model includes contact with the borehole wall allowing a range of stabilization geometries while removing bit-formation interaction effects. The results of exercising the model help develop new insights into both vibration measurement diagnostics and mitigation strategy execution.

Presented here is a review of other …