Best Practice in Hydraulic Fracturing: Reducing the Environmental Footprint
- Francois M. Auzerais (Schlumberger)
- Document ID
- World Petroleum Congress
- 21st World Petroleum Congress, 15-19 June, Moscow, Russia
- Publication Date
- Document Type
- Conference Paper
- 2014. World Petroleum Council
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- 51 since 2007
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Hydraulic fracturing dates back to the middle of the last century. Originally, the use of the process was restricted to relatively high permeability sandstones to which the hydrocarbons would flow to and become trapped. Most of the early treatments on the last part of the 1900s were relatively small treatment that bypassed drilling damage and stimulated the target formation a few hundred feet the wellbore.
Evolution of Hydraulic Fracturing
In the early 1990’s, advances in modeling contributed to the successful hydraulic fracturing of lower permeability, tight gas environments. New hydraulic fracturing fluid systems enabled a reduction in gel concentrations and improved well productivity.
As tight gas development, in largely sandstone formations, continued into the mid-2000’s, multi-zone pays become of interest to the operators. A key enabler to stimulating discreet intervals over a large gross interval was the introduction of more efficient staging technologies. During this era, it was not uncommon for an operator to stimulate 5 to 10 small sands over a +200 ft of gross interval in a single fracturing event. To make these wells economic, the operator had to perform this operation a dozen or more times on each well. In this period, we also saw the introduction of pad drilling where an offshore mentality was used to drill multiple land wells from a single surface location. In turn, this enabled us to work more efficiently.
Towards the end of the last decade, we saw the emergence of unconventional shale resources. In the beginning, shale gas was the main target. But, as the process of combining horizontal wells with multistage fracturing was further refined, the technique was also applied to tight oil reservoirs. The key to success in the shale resources is maximizing reservoir contact. The difference between gas and oil in this environment is that gas wells utilized slickwater fluids to introduce “fracturing complexities” while oil required higher conductivity and utilized primarily conventional crosslinked fluid systems. Additionally, job sizes in unconventional oil wells are typically smaller in size than their gas well counterparts and injection rates are lower.
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