|Authors||A. Maliardi (AVA/Newpark Drilling Fluids) | C. Molaschi (AVA/Newpark Drilling Fluids) | G. De Grandis (AVA/Newpark Drilling Fluids) | M. Molina (AVA/Newpark Drilling Fluids) | L. Bussaglia (AVA/Newpark Drilling Fluids) | F. Arpini (AVA/Newpark Drilling Fluids) | H. Dearing (AVA/Newpark Drilling Fluids)|
|Publisher||Offshore Mediterranean Conference|
|Source||Offshore Mediterranean Conference and Exhibition, 25-27 March, Ravenna, Italy|
In a field characterized by highly fractured carbonate reservoirs, the standard drilling fluid practices have been to drill the reservoir using low weight calcium carbonate polymer muds.
While generally successful, use of this fluid has resulted in high torque and low rates of penetration (ROP) in wells with extended horizontal sections. A cost effective alternative was needed to improve in these areas and still meet business objectives.
As detailed in this case history, a High Performance Water-Based Mud (HPWBM) system was introduced to drill the curve and the horizontal section in a side-track of an existing well. The application of this fluid further optimized drilling performance in the field. This resulted in improved control of the wellbore trajectory, reduced the well path tortuosity and greatly improved the ROP.
Use of the HPWBM showed excellent results in reducing torque and increasing ROP while helping extend the lateral and maintain wellbore stability. Lubricity was maintained while drilling the interval, achieving an average ROP of 3.8 m/hr for the curve and an average ROP for the horizontal section of 7.5 m/hr.
The average torque experienced while drilling was 629 kgf.m (4550 lbf.ft) which was well below the torque limit of the drill string. These successful results proved the reliability of the HPWBM, allowing the drilling a 527-meter curve section and a 2010-meter horizontal section in a 6350 m measured depth well with a 3848 m true vertical depth.