As California entered a period of severe drought in 2008, the challenges of using thermal methods to extract heavy oil became compounded by the difficulty of securing freshwater sources from
which to generate the high-quality steam that these methods require. In an effort to manage the crisis, then-Gov. Arnold
Schwarzenegger proclaimed a state of emergency and enacted widespread water-conservation measures.
The drought, which officially lasted until March 2011, impacted heavy oil fields in the state that rely on affordable fresh water to feed boilers in thermal techniques such as steamflooding and cyclic steam stimulation (CSS). Essentially, these thermal techniques involve the injection of steam into wells to heat the viscous oil to flowing temperatures. As the drought intensified in California, the prospect of feeding boilers with oilfield produced water instead
was studied as an alternative.
One operator, Seneca Resources, found that it could no longer practically obtain the 7,000 bpd of fresh water it needed for its heavy oil operations in Bakersfield. Seneca, the exploration and
production segment of Houston-based National Fuel Gas Company, develops oil and gas reserves in California and the Marcellus shale of Pennsylvania, and has been expanding into Kern County, California, since 1998.
As a result of shortages in 2008 and 2009, Seneca was denied
fresh California aqueduct water from the Lost Hills Water District and, instead, had to resort to purchasing its supply from farmers in the area. It became increasingly attractive to find a way to transition from fresh water to produced water for its steam production...
In its investigation, Seneca looked at promising pilot plant testing results for a neighboring oil producer by design and manufacturing firm Eco-Tec, based in Pickering, Ontario, Canada. The company,
which builds water, chemical and gas purification systems, was active in running pilots in the Bakersfield area using its RecoPur ion-exchange softeners. The system makes use of a novel ion exchange process, called Recoflo, which allows the use of either SAC or WAC resin to soften produced water at TDS levels up to 12,000 mg/L, to levels of residual hardness less than 0.1
By using adequate dosages of highpurity brine, the company claimed its technology could eliminate the use of acid and caustic, even for regeneration of WAC resins. The company also indicated that its technology could provide 40%–80% reduction in salt and waste from regeneration compared with conventional softeners. These were critical factors for Seneca going into the project. The manufacturer also provided a micromedia pre-filtration
system to reduce downstream softener fouling and associated problems.
The equipment was more compact and had a smaller footprint than competing systems. It’s fully automated design provided for simple operation, along with easy adjustment to variable feed water conditions and—if needed—effective insitu resin cleaning.