In N.M., a sea of ‘frack hits’ may be tilting production by Gayathri Vaidyanathan, March 18, 2014, E&E News
John Alexander, vice president at Dugan Production Corp., does not mind that other oil companies have fracked his company’s oil wells at least 36 times. Each event flooded the well bores with nitrogen, which is commonly used in hydraulic fracturing in the San Juan Basin. Alexander called the floods an “inconvenience,” nothing more. That’s because Dugan has a working interest in some of Encana (USA) Corp.’s wells, Alexander said.
But not all companies do. In New Mexico, more than 103 individual wells were affected by downhole communication incidents involving Encana, QEP Energy Co., WPX Energy Inc. and nine other drillers. Downhole communication, or a frack hit, occurs during hydraulic fracturing, a process in which companies inject water, chemicals and sand into shale formations at high pressures to fracture shale rock and release oil and gas. Sometimes the fractures connect with existing wells nearby, and the injected fracking fluid can cross over more than half a mile and enter the adjacent well bore. In some cases, if a well is not shut in, it can cause a spill at the surface.
In the worst-case scenario, which has not yet been documented in the United States, the high pressures of fracking rupture the casing and allow drilling fluid to leak into groundwater (EnergyWire, Aug. 5, 2013). The New Mexico Oil Conservation Division (OCD) said it was not aware of any incidents that have affected protectable groundwater. It has established a task force between regulatory agencies and the oil and gas industry to understand the situation, and began collecting information on the incidents in October 2013.
The records were provided to EnergyWire in response to a Freedom of Information Act request. The incidents in New Mexico happened between 2007 and 2014, and in at least one case, there was a spill of fracking fluids at the surface (EnergyWire, Oct. 24, 2013). In other cases, offset well operators found fracking fluid or drilling mud in their wells, which had to be cleared out. M&M Production, for instance, found drilling mud and production water in one of its wells after a nearby well operated by Logos Resources Inc. was being fracked.
Arguably, no company has been affected as much as Dugan Production, which reported 36 frack hits to the OCD. The company has conventional oil wells in the Gallup sandstone formation, many of which have been in operation for decades. They have mostly been affected by Encana, which has drilled and hydraulically fractured horizontal wells into the Mancos Shale formation, said Alexander. The fracking fluid that Encana used is composed of nitrogen, water, sand and chemicals. The nitrogen keeps the solution foamy, like shaving cream, and reduces the amount of water used in the frack, Alexander said. Most companies use a mix of 70 percent nitrogen and 30 percent water in the San Juan Basin.
At times, when Encana fracked its wells, the nitrogen would show up half a mile away inside Dugan’s vertical wells. The vertical wells are operated using pumpjacks, or nodding donkeys, that physically lift oil out of the ground. The presence of nitrogen in the wells interferes with the functioning of the pumpjacks. This is a minor inconvenience, Alexander said. Alexander does not mind the frack hits because Dugan has an interest in some of Encana’s wells. And Encana warns Dugan Production three weeks before each frack job so Dugan can shut in its well. Suspending production means that though fracking fluids may enter the well bore, they are unlikely to travel to the surface and cause a spill.
Under pressure, production may rise [And water wells may turn into better gas wells than water wells, as happened in Rosebud, Alberta]
Sometimes, frack hits increase production in nearby conventional vertical wells, as has been documented by companies in New Mexico. For instance, a conventional oil well owned by McElvain Energy Inc. of Farmington, N.M., that is close to an Encana well being fracked suddenly began producing much more oil. Prior to fracking in October 2012, the McElvain well had been producing 0.5 barrel per day (bpd) of oil and 25 thousand cubic feet (mcf) of natural gas. Encana finished fracking on Dec. 2, 2012. By February 2013, the McElvain well was producing 25 bpd of oil and 152 mcf of gas. The company noted that it could not be sure that frack hits were the cause of the increase in production, since it had not done the analysis.
Other companies also noticed an uptick in production from their conventional oil wells. One of Dugan Production’s wells in September 2013 produced 347 barrels of oil and 129 mcf of gas. A month later, the well produced 1,500 barrels of oil and 9,533 mcf of gas. To put that in context, that is more oil than the well has produced on average since it was drilled in April 1996.
So where is the oil coming from?
Doug Hock at Encana thinks hydraulic fracturing is stimulating production at these nearby wells. The process of fracking causes an immense pressure buildup underground, which then looks for an exit. If there is an older well nearby, the pressure can push oil and gas into that older well. [And into citizen water wells, notably when Encana fracs hundreds of gas wells above the Base of Groundwater Protection and directly into fresh water aquifers] “Once the well is opened up and the pressure relieved, there can be a temporary increase in production in the well as the built-up pressure releasing oil and gas from the reservoir,” said Hock in an email. [Unfortunately, there has been no decrease in the gas production in Rosebud citizen water wells]
Frack hits can also decrease production at certain wells, as was seen at a well owned by Elm Ridge Resources. Elm Ridge had been regularly shutting in the well since 2011 and building up pressures underground. The pressure buildup would improve production. But since a nearby well was hydraulically fractured in 2013, the well saw an influx of fracking fluid for two weeks, Elm Ridge wrote to the OCD. Since then, the well has not produced oil or gas.
…
Most of the wells that are frack hit get contaminated with fracking fluids in their well bore, which suggests material is moving between the two parcels of land. … The OCD did not respond to EnergyWire’s request for comment on the issue before deadline. The COGCC said Hergenreder’s situation was unusual and other landowners have not complained. [Emphasis added]