Abstract
Abstract
Development of the tight gas Khazzan Field in Sultanate of Oman has progressed through many years of extensive learning. Massive hydraulic fracturing operations became a key part of the completions in the Barik reservoir. Fracturing design was optimized with time, eventually achieving a fit-for-purpose fracturing design. However, when activities moved towards the south, increase in reservoir gross thickness was encountered, and implementation of the standard fracturing design led to increased number of screenouts.
Many parameters were examined to discover the root cause of the increased screenout rate, such as changes in pumping schedules, changed reservoir properties, fracture execution data, completion details, and many others. After the thorough analysis, it was found that lack of hydraulic width played the major role in most of the screenouts. Multiple solutions to resolve the lack of hydraulic width were considered: increase in gel loading, increase in pumping rate, optimizing pad volume, changing completion strategy, reducing job size, reducing proppant concentration, etc.
After thorough consideration, it was found that removing the larger proppant might be an optimum solution for this challenge. The standard fracturing design typically included 70% of smaller ceramic 20/40 and 30% of larger 16/30 ceramic proppant. Performed production analysis has shown that some reduction in fracture conductivity by removing 16/30 proppant will have minimum negative effect on well productivity in conditions of the tight gas Barik reservoir. The results of this change have exceeded expectations: screenout rate has declined from 38% to 0% while post-fracturing production has shown the same gas rates as those with larger proppant.
This paper shows how a simple but properly evaluated solution has regained the success of proppant fracturing operations in Sultanate of Oman.