ABSTRACT
Integrity of well structure is a vital factor to produce hydrocarbons from subsurface. It is important that well structure along with cement behind the casings remains intact to get controlled and risk free production during life of a well. This objective is achieved by making every effort to ensure good cement behind pipe and selecting suitable well tubulars honoring reservoir fluid composition and fluid flow rates. In case the criteria of well integrity is not met, flow of fluids behind casing and communication between tubulars create problems and may lead to uncontrolled flow of well fluid creating environmental and safety hazards.
Bagla gas field is located within the Indus Basin with producing horizon in Lower Goru Formation of Cretaceous age. This is a single well field, which was drilled by Phillips Petroleum Exploration Ltd during 1988. Later on OGDCL acquired this field. The field could not be developed due to its marginal reserves, remote location, non-availability of gas buyer in near vicinity of the field and non-attractive economics in case gas is sold to SSGCL due to high cost of pipeline quality gas to SSGCL gas transmission network.
During April 2004 gas channeling to surface was observed in the nearby area located within a radius of 2-3 km from the Bagla well. This gas channeling was causing environmental and safety hazards in the area. This paper discusses the measures taken by OGDCL to diagnose the cause of problem and efforts made to control the well to contain the environmental and safety hazards in the area.
