Oil Field Surface Expressions

​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​Under strengthened regulations effective ‪April 1, 2019, surface expressions violate state regulations enforced by the Geologic Energy Management Division (CalGEM). A surface expression can occur when steam injected under pressure to produce oil breaks through natural geologic barriers and comes to the surface. The releases in the Cymric, Midway Sunset, and McKittrick oil fields in Kern County are not near population centers or sources of drinking water. All of the expressions are contained and are clustered in a few areas.‬ CalGEM​ is collaborating ​with independent experts from the Lawrence Livermore and Sandia National Laboratories to investigate the expressions in the Cymric field.

Refer to the California Office of Emergency Services (CalOES) Spill Report​ for additional information ​on active surface expressions, including volumes of oil and water released.​ 

Use "Search" to enter the incident number, for example, 19-7291 (numbers available below), ​​for reports.​​​​

Maps of Western Kern County

StoryMap: Interactive, high-level walk through of the incident

Interactive e.s.r.i. story map viewer of oil field surface expressions ​​​​

Web Map of Western Kern County​​

Interactive GIS map of Cymric surface expressions 

​Note: Page updated November 2021​​​​

Aera Coalinga

  • Began April 9, 2021 (steam only – no CalOES Spill Report).  Stopped April 20, 2021.  Aera discovered a steam only surface expression (non-diatomite) on April 9, 2021, in their Coalinga Aztec lease at coordinates 36.23055, -120.37668.  Aera subsequently shut in all steam within 600 feet, including the closest well on steam at time of activation, Aztec 728 (019-24333). During the root cause investigation, cause was identified as steam communication through shallow casing holes at well “Aztec” 728 (API No. 019-24333) during a cyclic steam job. The well abandoned on May 6, 2021 and site restored.  With root cause identified and remediated, CalGEM has issued return to steam approval under certain conditions as per below. 

​Aera Lost Hills

  • CALOES Spill Report 21-1623:  Began March 26, 2021.  Stopped April 1, 2021. Aera discovered on March 26, 2021, a high energy steam to surface event in Lost Hills (non-diatomite, Tulare/Etchegoin steamflood), approximately. 40 feet north of Well #MD2412-13 (030-63227), approximate. coordinates 35.66413, -119.76941, which was stopped by April 1, 2021. A 600- foot steam block was established and root cause investigation is still ongoing. ​

Chevron Cym​ric Gauge Setting 5 Area

  • CalOES Spill Report 20-1575: Began March 19, 2020, still active (drains into Gauge Setting 5 collection area).  CalGEM is reviewing Chevron's root cause analysis (submitted April 30, 2020) of an oil and water surface expression (Setting #5 03/19/20) reported from a ledge above Gauge Setting 5A on March 19, 2020. The flow ceased March 20 and reactivated March 24. It is active intermittently active. The operator drains the ongoing flow into a containment area protected with berms, netting, and beams.  ​
  • CalOES Spill Report 20-1649 / 21-1190: Began February 28, 2020, still active within a berm’d & netted containment area, which is then pipelined to Gauge Setting 5 collection area. This incident is a reactivation of a surface expression from a hillside vent that initially seeped fluid from November 8-30, 2019. That incident is first described in CalOES Spill Report 19-7186.  For three weeks, Chevron reported 2020 fluid data in CalOES Spill Report 19-7186. CalGEM required Chevron to create a new spill report for what it considers a new event in 2020. The operator submitted the 20-1649 report on March 23, 2020. It captures fluid data from March 21, 2020, forward.  OES 20-1649 has now, as of March 4, 2021, been superseded by a new OES 21-1190 due to file size limitations for a single OES number (max 242 entries).  The operator is working on select wells in an effort to interrupt the energy or fluid flows from potential pathways that may be feeding this surface expression and others.
  • CalOES Spill Report 19-7291: Began November 13, 2019. Stopped November 14, 2019. Recovered volume: 20 barrels water and oil. Located approximately 120 feet west of March 29, 2018, expression in Gauge Setting 5-D area. Chevron posted danger signage and lights. External company monitoring for any gas emissions. Chevron notified of two vertical cracks on hillside and road above. Operator addressing.  Environmental cleanup complete and site restored.    ​.    

  • CalOES Spill Report 19-5407: Began August 21, 2019.  Stopped October 15, 2019. Recovered volume: 19,925 barrels water and oil. Environmental cleanup complete and site restored.   

  • CalOES Spill Report 03-1581​: Began March 23, 2003, still active (drains into Gauge Setting 5 collection area). On June 20, 2019, Chevron reported fluid volumes related to a series of surface expressions from 2018 and earlier that are being directed into the GS-5 separation plant. Since these expressions continue to flow after April 1, 2019, they are in violation of the new April 1, 2019, regulations. CalGEM sent Chevron a Notice of Violation on August 23, 2019, directing the company to stop the expressions. 

Chevron Cymric McPhee 36W Area​

  • CalOES Spill Report 19-6580:  Began October 13, 2019. Stopped October 14, 2019. Recovered volume: 1,931 barrels water and oil. Hillside vent at northern end of Cymric field. Spill area cleaned; site cleanup continues.  
  • ​​CalOES Spill Report 19-6568Began October 12, 2019; reactivated with steam and fluid October 15-18; reactivated October 22, intermittently active until stopped November 11, 2019. Recovered volume: 13,160 barrels water and oil. Located  275 feet east of CalOES Spill Report 19-6386 expression and 294 feet north of CalOES Spill Report 19-6221. Chevron contained flow; lights, danger signs, and propane cannon (to deter wildlife) installed. External company monitoring for low (thus far) gas emissions. Environmental cleanup complete and site restored.

Chevron Cymric 1Y Area

Sentinel Peak Resources (SPR) Cymric McKittrick Front

  • ​​CalOES Spill Report 20-2154: ​​Began April 20, 2020. This surface expression was inactive from May 28, 2020 until becoming intermittently active again on June 21. It has been i​​nactive since June 26, 2020. Cumulatively, the surface expression has produced 1,530.5 barrels of oil, 3,181 barrels of water, and 415 barrels of mud.​

Sentinel Peak Resources (SPR) Cymric ​Star Fee

  • CalOES Spill Report 20-6113.  Began November 3, 2020 (stopped same day).  Reactivated December 19, 2020 and January 23, 2021 for short durations.  Inactive since January 23, 2021.  The original event was discovered, at 2:30 am at coordinates 35.341377252, -119.657706220 with intermittent blows of high energy steam, mud, and ~1 BBL oil released to ground in an oilfield disturbed area, and not affecting any blue-line/sensitive areas. SPR has established a caution area around the site with danger signs installed, and are continuing to monitor with 150- foot steam block implemented as per regulations.  
  • CalOES Spill Report 20-2763: Began May 24, 2020.  Stopped May 27, 2020. Reported volume as of June 1: 70 barrels of water, 16 barrels of oil, 1,614 barrels of mud.
  • CalOES Spill Report 19-5656: Began September 1, 2019 (stopped same day). Recovered volume: 10 barrels water and oil. 

Berry Petroleum Midway Sunset ​Southwestern

  • Cal OES #20-4392: Began August 15, 2020.  Stopped August 20, 2020.  A surface expression in the Berry Petroleum-operated Southwestern lease of the Midway Sunset oil field in Kern County was reported at 1 a.m. on August 15, 2020, which was stopped by August 20, 2020.  A root cause investigation identified a shallow casing hole in idle well 48-​56​ (API No. 0403042139) which served as a conduit to the near surface  This well was subsequently abandoned. With root cause identified and remediated, CalGEM has issued return to steam approval under certain conditions as per below. 

Sen​tinel Peak Resources Midway Sunset ​Keene​

Sentinel Peak Resources Midway Sunset Reardon

Sentinel Peak Resources McKittrick Richfield