Integrity of well structure is a vital factor to produce hydrocarbons fromsubsurface. It is important that well structure along with cement behind thecasings remains intact to get controlled and risk free production during lifeof a well. This objective is achieved by making every effort to ensure goodcement behind pipe and selecting suitable well tubulars honoring reservoirfluid composition and fluid flow rates. In case the criteria of well integrityis not met, flow of fluids behind casing and communication between tubularscreate problems and may lead to uncontrolled flow of well fluid creatingenvironmental and safety hazards. Bagla gas field is located within the Indus Basin with producing horizon inLower Goru Formation of Cretaceous age. This is a single well field, which wasdrilled by Phillips Petroleum Exploration Ltd during 1988. Later on OGDCLacquired this field. The field could not be developed due to its marginalreserves, remote location, non-availability of gas buyer in near vicinity ofthe field and non-attractive economics in case gas is sold to SSGCL due to highcost of pipeline quality gas to SSGCL gas transmission network. During April 2004 gas channeling to surface was observed in the nearby arealocated within a radius of 2–3 km from the Bagla well. This gas channeling wascausing environmental and safety hazards in the area. This paper discusses themeasures taken by OGDCL to diagnose the cause of problem and efforts made tocontrol the well to contain the environmental and safety hazards in thearea. Introduction Bagla is a single well gas condensate field located in Thatta Exploration Lease. The field is located about 150 km East of Karachi and 87 km South ofHyderabad. Nearest OGDCL well Nur # 01 is located at 3.5 km towardssouthwest.

Exploration and exploitation of low permeability gas reservoirs in mature developed field is a challenge. It involves re-evaluation and characterization of reservoir properties of the producing zones. As the field understudy is mature and needs to understand the different pressure regimes and available gas potential in depleted and un-depleted zones before embarking on the exploitation of these low permeability reservoir. In past, development of low permeability reservoir was considered uneconomical due to low flow rate and longer pay out time. However, present gas prices and existence of infrastructure of surface facilities on field shifts the negative economics of low gas flow rates to positive direction. Consequently, any gas flow rates are deemed to be economical and a source of extra revenue. In this field, both carbonate and sandstone are producing reservoirs. Carbonates are of low permeability reservoir while sandstone is fragile and represent high permeability reservoir. Initially DSTs were conducted in both reservoirs while wells were completed in sand stone reservoir. Due to the fragile nature of the sandstone formation, gravel pack completion was used to avoid sand production. Initially, high permeability sand stone formation was produced. Volumetric and dynamic data was collected and analyzed to determine the undepleted part of the reservoir. The dynamic data indicated that low permeability reservoir has insignificant contribution and needs to be developed. Petrophysical properties of the carbonate reservoir were reviewed; new DST was conducted in the carbonate reservoir. During DST, longer build up was planned for reliable pressure data. After DST analysis, it was observed that it is low permeability reservoir with high skin value and need to be stimulated. Acid stimulation was carried out that have resulted in significant improvement and the well was put on production with sustainable production rate. In this paper, integrated approach of evaluation of geological and dynamic data that have resulted in successful recompletion of wells in low permeability carbonate reservoir will be discussed. The lesson learned from this successful evaluation and production of low permeability reservoir can be used for the exploitation of these reservoirs in the country.