TX 75083-3836, U.S.A., fax 01-972-952-9435. AbstractThe use of coiled tubing to clean sand from well bores remains one of the industries major areas of activity in well intervention. Recent research work programs have focused on sand transport and cuttings bed modeling with both Newtonian

TX 75083-3836, U.S.A., fax 01-972-952-9435. AbstractThe use of coiled tubing to clean sand from well bores remains one of the industries major areas of activity in well intervention. Recent research work programs have focused on sand transport and cuttings bed modeling with both Newtonian

TX 75083-3836, U.S.A., fax 01-972-952-9435. AbstractWater production in mature fields is a common situation. In many mature areas, every barrel of oil is being produced with six to ten barrels of water. The production of water results in increased operating expenses along with other water related well problems like scale, fines migration, sand face failure, water loading in wellbores etc.

TX 75083-3836, U.S.A., fax 01-972-952-9435. AbstractMany wells are damaged in the course of drilling and workover by the use of drilling muds, drill-in fluids, and killpills that contain, amongst other things, polymeric

Wellbore stability is important for successful horizontal and extended reach drilling (ERD) wells. Hole instability problems associated with ERD wells can sometimes change the original development plan because of complications and unforeseen operational and geomechanical issues.This paper presents a case study from offshore Vietnam, where historically, no significant wellbore stability problems had been reported for vertical and low-angled wells. There were plans to develop the field by drilling highly deviated and ERD wells from one platform. However, instability problems and significant non-productive time from frequent pack-offs, tight holes and stuck liners were encountered while drilling one of the designed wells. The hole was sidetracked three times and finally drilled at a lower angle than originally planned.Geomechanical analysis using core, well log, drilling data and experiences were used to build a field scale geomechanical model characterizing the in situ stress, pore pressure and rock mechanical properties in both the overburden and reservoir sections. Stress-induced borehole failure observed in image logs from an offset well and diagnostic analysis of failure mechanisms from cavings recovered from the problematic well provided significant insights into the likely nature of instability problems in the ERD well. Hole instability problems were attributed to the failure of weak bedding planes and anisotropic rock strength in the shales interbedded with sandstones. To control the weak bedding and anisotropic failure, stronger mud weights were needed than were in the original plan. The required mud weight for maintaining stability varies depending on wellbore trajectory and bedding characteristics. The usagee of high mud weights is unfavorable because of possible formation damage that could occur and the risk of fracturing the reservoir (because of lower fracture gradient). Consequently, the original ERD plan had to be revised and new optimum well trajectories designed that took into account any drilling issues, in addition to completion and productivity requirements.