Seismicity Intro

Oklahoma Corporation Commission’s Oil & Gas Conservation Division (OGCD) is implementing plans for the largest volume reduction yet for oil and gas disposal wells in western Oklahoma, according to IHS Markit.

The announcement is the latest effort in the state’s response to induced seismicity associated with produced wastewater injection. A report by the U.S. Geological Survey (USGS) published in 2016 stated that up to seven million people were at risk from man-made earthquakes.

RELATED: Expert Digs Into Oklahoma’s Induced Seismicity Challenges

Before 2009 in Oklahoma, the USGS said the state might have experienced one to two low-magnitude earthquakes per year. However, since 2017, Oklahoma has been experiencing one to two low-magnitude earthquakes per day, with a few instances of higher magnitude (between magnitude 5 and 6) earthquakes that caused some damage.

The USGS forecasted 2017 seismic rates for Oklahoma that are still significantly elevated compared to pre-2009 levels but lower than their peak in 2015, according to a report by the Energy Information Administration (EIA).

The recent decline of seismic rates may be related to decreased wastewater injection, possibly from actions by state authorities to regulate wastewater injection practices and restrict injection into the most sensitive areas, the EIA said.

In hopes to accelerate that trend, OGCD’s new earthquake directive not only takes aim at current volumes but at future disposal rates as well, according to OGCD Director Tim Baker.

“The data from the Oklahoma Geological Survey shows the earthquake rate has been dropping since we issued various directives reducing the then-current volume within the area of interest (AOI),” Baker said in a Feb. 24 statement. “The continued drop in earthquakes, as well as new data and input from the Oklahoma Geological Survey have caused a change in our orientation from focusing on current disposal volumes within the AOI to looking ahead to try and ensure there isn’t a sudden, surprise jump in those disposal volumes.”

In total, the new directive will cover 654 Arbuckle disposal wells in the AOI, he said.

Recorded instances of man-made earthquakes linked to injection wells, similar to what Oklahoma is currently facing, actually stretch back several decades.

In 1961, the U.S. Army drilled a 12,000-foot well at the Rocky Mountain Arsenal in the Denver Metropolitan Area for disposing Arsenal operations waste fluids. Injection began by 1962 and an unusual series of earthquakes began in the area shortly after.

More than 1,300 earthquakes were recorded between January 1963 and August 1967. Three shocks in 1965 caused intensity VI damage in Commerce City, Colo., and nearby communities with a 4.4 magnitude shock felt in Boulder, Colo.

The strongest (magnitude 5.3) and most widely felt shock in Denver's history was in 1967—it was felt in Laramie, Wyo., Goodland, Kan., and as far south as Pueblo, Colo.

Once the underground injection stopped, so did the earthquakes.

Scoop/Stack Activity Highlights

Scoop/Stack Activity Highlights July 2017 Map

1. Chesapeake Energy: 5/5/17

Chesapeake Energy Corp. (NYSE: CHK) operating subsidiary, based in Oklahoma City, has completed a horizontal Oswego producer in Kingfisher County, Okla.

Located in Section 27-19n-6w, #1H Kokojan 27-19-6 was perforated, acidized and fractured at 6,454 ft-11,017 ft. It is producing 169 bbl of oil, 556,000 cubic feet of gas and 873 bbl of water on artificial lift. It was drilled to the north to 11,116 ft and the true vertical depth is 6,280 ft.

The #1H Kokojan is the first horizontal Oswego producer in the eastern Stack play township, according to IHS Markit.

2. Continental Resources : 4/19/17

A Meramec discovery by Continental Resources Inc. (NYSE: CLR) in the Stack play is producing 15.3 MMcf of gas, 2,088 bbl of 55-degree-gravity condensate and 2,228 bbl of water per day.

The well, #1-4-33XH Angus Trust, is in Section 4-14n-12w of Blaine County, Okla. The Greenfield West Field well was drilled to the north to 22,164 ft, 12,208 ft true vertical, and bottomed in Section 33-15n-12w. It was completed at 12,472 ft-22,019 ft following a 36-stage fracturing and was tested on a 34/64-in. choke with a shut-in tubing pressure of 5,700 pounds per square inch (psi), and a flowing tubing pressure of 5,200 psi.

Oklahoma City-based Continental has a 78% working interest in the new producer.

3. Marathon Oil: 3/24/17

IHS Markit reported that Houston-based Marathon Oil Corp. (NYSE: MRO) has scheduled six new tests in a Stack play increased density project in Kingfisher.

The wells—#2-12MH Hansens 1607, #3-12MH Hansens, #4-12MH Hansens 1607, #5-12MH Hansens 1607, #6-12MH Hansens 1607 and #77-12MH Hansens 1607—will be drilled from a drillpad in Section 12-16n-7w. All are designed as single-section horizontal tests with total depths ranging from 12,496 ft to 12,605 ft within Section 12.

The #6-12MH Hansens is designed to test Upper Meramec at an estimated true vertical depth of 7,340 ft. True vertical depths for the other five range from 7,713 ft to 7,718 ft, presumably in Middle Meramec.

4. Marathon Oil: 3/20/17

A Stack play discovery by Marathon Oil is producing 2,070 bbl of oil, 3.29 MMcf of gas and 364 bbl of water per day from a treated Meramec lateral at 9,521 ft-17053 ft.

The #1-25XH Marjori is in Section 25-17n-10w in Blaine. The 17,375-ft well was drilled to the south and the true vertical depth is 9,411 ft. It bottomed in Section 36-17n-10w.

From a second well on the pad, #1-25XH Lloyd was tested flowing 1.553 Mbbl of oil, 2.38 MMcf of gas and 447 bbl of water per day from Meramec. It was drilled to 17,355 ft, 9,074 ft true vertical. Production is from an acidized and fractured interval at 9,551 ft-17,262 ft.

The venture was drilled to the north and bottomed in Section 24-17n-10w.

5. Vitruvian Exploration: 12/28/16

The Woodlands, Texas-based Vitruvian Exploration II LLC has completed a Scoop play-Woodford producer that flowed 18.6 MMcf of gas, 377 bbl of 56-degree-gravity condensate and 1,654 bbl of water per day.

The #1-27X26H Anita Fowler is in Section 22-4n-6w of Grady County, Okla. It was tested on a 32/64-in. choke. Production is from acidized and fracture-stimulated perforations at 14,727-20,677 ft. The 20,902 ft-well was drilled to the southeast and bottomed in Section 26-4n-6w.

6. Vitruvian Exploration: 12/1/16

Two Woodford gas producers in the Scoop play were reported by Vitruvian Exploration, drilled from a common drillpad in Section 35-3n-5w of Grady in the Anadarko Basin.

The #2-35XH02H Bragg initially produced 13.7 MMcf of gas with 4,893 bbl of water per day. It was perforated, acidized and fracture-stimulated between 16,084 ft and 25,132 ft in a south lateral terminating in Section 2-2n-5w in Stephens County, Okla. The well was drilled to 25,290 ft, 12,662 ft true vertical, and is on the eastern side of the Carter-Knox Anticline with the lateral drilled up-dip on the structure.

The #3-35XH02H Bragg, which was drilled 10 ft to the north on the pad, is producing 12.9 MMcf of gas and 6,243 bbl of water per day. It was drilled to 25,942 ft with a true vertical depth of 15,883 ft and is producing from perforations at 16,178 ft-25,787 ft. It was tested on a 47/64-in. choke in a parallel lateral 660 ft east of #2-35XH02H.

According to Vitruvian, the Woodford reservoir underlying Section 2 is about 350 ft thick, has average porosity of 6% and water saturation of 30%.

7. Continental Resources: 7/18/16

Continental Resources completed a high-volume horizontal Woodford producer in the Scoop play in Carter County, Okla.

The #1-17-20XH Gretta is in Section 17-3s-3w, and it initially flowed 9.42 MMcf of gas, 978 bbl of 56-degree-gravity condensate and 3,000 bbl of water per day. Production is from a fracture-stimulated interval at 13,606 ft-20,206 ft. It was tested on a 54/64-in. choke with a shut-in tubing pressure of 1,800 psi and a flowing tubing pressure of 1,237 psi.

The Ardmore Basin well was drilled to 20,300 ft, and the true vertical depth is 12,553 ft. It was drilled to the south and bottomed in Section 20-3s-3w.

Larry Prado, activity editor, can be reached at lprado@hartenergy.com.