Despite an ongoing oil glut, hydraulic fracturing shale drillers plan to expand production, keeping the pressure on the energy market and related exchange traded funds.

The United States Oil Fund (NYSEArca: USO), which tracks West Texas Intermediate oil, has declined 18.8% year-to-date. [Oil ETF Traders Try to Time Market Bottom]

WTI crude oil futures are hovering around $74.5 per barrel.

Nevertheless, companies like Devon Energy Corp (NYSE: DVN), Continental Resources (NYSE: CLR) and EOG Resources (NYSE: EOG) want to pump more oil from their prime drilling sites while diminishing output from their least productive sites, reports Asjylyn Loder for Bloomberg.

Devon Energy expects to increase output by 25% next year. Continental Resources will raise production by as much as 29%. EOG Resources said it will maintain its “double-digit” growth streak in 2015. Meanwhile, Pioneer Natural Resources (NYSE: PXD), the most active driller in West Texas’ Permian Basin, has stated it will add as much as 21%.

“There’s a lot more production coming online this year and in the first half of 2015,” Jason Wangler, an analyst at Wunderlich Securities Inc., said in the article. “This isn’t a machine that you can turn on and off with a switch. It’s going to take months, if not quarters, to turn it around.”

The falling oil prices have been weighing on the energy sector, notably hydraulic fracturing or so-called fracking shale producers due to the high cost of entry – Citigroup argued that “full-cycle” costs, which include land, infrastructure, well drilling and operating costs, for new shale projects require oil prices of at least $70 to $80 per barrel.

Consequently, the Market Vectors Unconventional Oil & Gas ETF (NYSEArca: FRAK), which includes DVN 5.5%, CLR 0.9%, EOG 8.1% and PXD 4.2%, has declined 18.2% over the past three months, whereas the Energy Select Sector SPDR (NYSEArca: XLE) decreased 10.1%.