A recent review on Hydraulic Fracturing Survey of Industry Practices suggests that two-thirds of the treatment in the U.S. fail to reach the optimized well productivity goals. Careful review of the data show that the primary reasons for such failure include gross assumptions made in the understanding of the reservoir parameters and thereby resulting in inefficient fracture design, improper post-fracture analysis techniques and in certain cases the use of inappropriate analytical and numerical models. Review of hydraulic fracture treatments in various other parts of the world also show similar discouraging news.
The news does get better. A series of case studies performed in various parts of the world reveal that the aspects that cause the failures are the same items when paid attention to can provide great dividends and pave the road to treatment improvement and optimization. Key to a successful treatment starts with a design based on clear understanding of the reservoir properties impacting production following fracturing. Proper treatment implementation is another key element. Use of real time monitoring of bottom-hole pressures to the use of passive seismic / tiltmeter technology can have significant effect. It is rare that we know the growth of hydraulic fracture away from the well bore and as such post-treatment evaluation is critical to treatment optimization. The important point to recognize is the need for a closed-loop workflow applied on a field wide basis and not necessarily on every well.
We use field case study examples to show how improved identification of productive intervals, improved fit-for-purpose stimulation design, clearer understanding of the results by comparing it to predicted values lead to reduced cycle time and also the reduction of the cost per hydrocarbon unit.