Publications

Annular gas flow during and after cementing is a frequent problem in areas where oil and gas producing reservoirs are young and shallow gas formations are present. Areas considered potentially severe include the Gulf of Mexico, South China Sea, Indonesia, Malaysia, and areas where Miocene aged formations produce oil and gas.Annular gas flow may result in moderate to severe problems such as Sustained Casing Pressure (SCP), loss of well control, blowouts etc.In one Indonesian field over a two-year, 150 well drilling period, shallow gas flow combined with sand characterized by poor compressive strengths resulted in numerous wells with SCP, three rig evacuations and two rig fires. A mechanical solution using a casing annulus packer (CAP) and port collar (PC) was implemented to seal the annulus above the gas source immediately after “bumping the cement wiper plug on the surface casing primary job and providing a second stage cementing option in cases of poor displacement or losses or possible gas influx during the primary job.To date, 220 casing completions with CAP and PC have been achieved in this field with no severe problems. Based on prior experiences and costs associated with remediation of a well with annular gas flow, the mechanical control technique has effectively reduced the overall well costs in addition to drastically improving HSE issues.