Managed pressure drilling (MPD) is an effective solution to obviate the drilling problems of narrow drilling window between the pore and fracture pressure, such as well kick and loss and well collapse and stuck. The Constant Bottom Hole Pressure (CBHP) technique, one of the MPD variants, was selected to freeze bottom hole pressure in narrow area between pore and fracture pressure as a safe method to drill without loss and gain.
The MPD method was used to drill FARZAD-03 well initially starting at a small size compared to conventional mode, followed by a 17.5" hole section for well A-03 much longer than before. By controlling the drilling fluid Equivalent Circulation Density (ECD) through the narrow pressure window, drilling operation continued without facing any problems. Effective drilling of the troublesome formations could help to achieve the target even deeper than before and ensure the safety of the operation with the aim of CBHP.
This article provides for the first time, an overview of the current MPD applications as well as its modeling in hydraulic calculations to achieve a safe drilling in the complete loss zone.
According to definition of IADC, Managed Pressure Drilling (MPD) is an adaptive drilling process used to precisely control the annular pressure profile throughout the wellbore. The objectives are to ascertain the downhole pressure environment limits and to manage the annular hydraulic pressure profile accordingly. MPD is intended to avoid continuous influx of formation fluids to the surface.
In this study, Constant Bottom Hole Pressure (CBHP) as one of the key parameters of the MPD, is used to implement this analytical analysis throughout Jahrumi, Kazhdumi, Dariyan, Fahliyan, Hith and Surmeh formations so as to keep ECD between pore and fracture pressure gradient.
This offshore oilfield which has been located in the common sea border of Iran and Saudi Arabia confronts the operators with a multitude of major problems as compared to other typical formations on the other side of the Persian Gulf. (Fredericks, et al., 2010).
