Raageshwari Deep Gas field is located in RJ/ON 90/1 Block in western India is a retrograde gas condensate unconventional volcanic reservoir. It consists of streaks of low permeability sand which require hydraulic fracturing to achieve commercial production. Plug and perf stage technology along with limited entry was used to ensure that most of the productive pay was stimulated. Production data, Frac and Reservoir parameter were evaluated vis-à-vis Productivity Index (PI) and interdependencies were understood.
Multiple stages in a particular well were stimulated by hydraulic fracturing with each stage having from 1 to 6 perforation clusters to ensure maximum kH coverage. Different treatment designs varying in job size, proppant type, concentration and pumping rates were prepared and executed based on the formation type, net pay and petrophysical properties. After flowback and initial cleanup, the wells were hooked to the production facility. Memory production logging was then conducted in a time phased manner and the interpreted data was used to determine the PI evolution of individual cluster of all the 93 stages in 15 wells.
Time lapse PI of individual clusters as well as specific stages were plotted against:
Proppant pumped per net pay
Total proppant pumped
Elevation depths of the Fatehgarh, Basalt and Felsic formations of the reservoir stretching from north to south of the field.
Important observations resulted from this exercise such as:
The top most basalt stages are attributing a large portion of the 15 wells total cumulative production. It outperformed the shallower Fatehgarh sands which were thought to be more prolific.
Well PI clearly supports the changes expected in the reservoir quality from north to south of the field and is in line with the OH logs.
PI of wells in a particular area shows gradual improvement in contrast to the other wells PI.
Positive effects of flowing back an inferior quality pay before fracturing the upper superior quality pay.
This study will not only assist in determining the optimum proppant pumped per net pay height for different formations but also facilitate in eliminating frac stages in a well which would result in significant cost reduction in upcoming development campaign of 42 wells.
This holistic workflow will be used for refining the number of frac stages in a well as well as determining an ideal proppant quantity for a particular stage in volcanic pays. Detailed analysis of production data supported in identifying the key frac and reservoir parameters which subsequently will aid in improving hydraulic fracturing efficiency. Representative case histories of production results assisted in finalizing well services activities to improve the overall well PI.