Hydraulic fracturing is the proven stimulation technique to exploit hydrocarbon reserves trapped in tight gas Indian reservoirs especially in Mandapeta field of Southern India. Fracturing technique was customized to obtain designed fracture geometry which in turn resulted in very good post frac gas production rates. This paper deals in detail, the necessity of fracturing in Mandapeta field, meager production gains obtained in earlier fracturing treatments, challenges for fracturing, quality assurance and quality control of fracturing fluid, design and successful execution of fracturing technique.
Mandapeta field is located in Krishna Godavari Basin situated in Southern part of India. Customization of fracturing technique produced impressive gas production rates from Mandapeta field compared to earlier treatments. Poor geophysical properties of the reservoir, leak-off characteristics, completion constraints and high near wellbore frictions were some of the challenges observed during fracturing treatments. As the reservoir is having very low permeability, hybrid fracturing treatment with a pad comprising around 75 percent linear / slick gel followed by cross-linked slurry was designed and implemented successfully.
Gas production gains up to 37000m3/d in a single well was observed. 20/40 mesh high strength proppant was used in these treatments and maximum job size pumped was 151MT. Hybrid frac treatment was carried out in an exploratory location which resulted in impressive gas gain paving a way to further development of field. Pre-frac acid treatments improved the well bore connectivity to the reservoir thereby enabling the higher proppant concentrations to pump during the treatments. Chemical compositions addressed the surface tension and mobility concerns of the fracturing in gas reservoirs which resulted in faster cleanup and gas production. Recent successes of fracturing made a way forward to aggressive fracturing campaigns in this field.
Hydraulic fracturing treatments have to be customized to specific reservoir conditions so as to obtain success. Candidate selection, modeling designs using sensitivity analysis, suitable pre-frac treatments, lab studies for optimization of fracturing fluid, customized hybrid fracture treatments played vital role in successful execution of fracturing treatments in Mandapeta field of Southern India which can be applied to other tight gas reservoirs.