Why did the customer contact us?
The producer of the lease implemented water injection or flooding of the producing formation at the site beginning in the early 1990s to enhance the recovery of crude oil. Formation water from the producing formation was originally injected into the designated injection wells, including the suspect well located at the site. A water well completed in a deeper formation, which underlies the producing formation, was also utilized as a source of makeup injection water for the lease.
A hydrocarbon and produced water seep was identified in a creek which traverses the site. The producer immediately terminated production operations at the site in accordance with RRC instructions. The seep was identified in the creek to the east of the suspect injection well. The RRC requested the producer initiate containment and remediation operations at the seep to manage the discharge of phase-separated hydrocarbons (PSH) and produced water into the creek and backflow to the injection wells. The producer deployed oil absorbent pads and booms and other equipment to manage the seep at the site.
Several plugged production wells completed in the 1940s on behalf of other producers are located at the site. Based on the available RRC documentation, each of these wells were drilled utilizing cable-tool drilling techniques and were plugged subsequent to completion due to an insufficient volume of crude oil for production or at a later date due to diminished production.
The producer re-entered select plugged cable-tool wells to evaluate each as a potential source of the seep. Ensolum personnel documented the plugging materials and depths of each material associated with each cable-tool well, collected PSH samples and produced water samples. PSH samples were submitted for paraffin (P), isoparaffins (I), aromatics (A), naphthalene (N), and olefins (O) analysis. PIANO analysis or “fingerprinting” is commonly utilized to evaluate the source and/or make-up of PSH samples. The water samples were submitted for cations/anions (potassium, chloride, sulfate, calcium, magnesium, sodium, nitrate as nitrogen, alkalinity, bicarbonate alkalinity and carbonate alkalinity) analysis to evaluate the likely geologic formation where the water originated.
Ensolum personnel also reviewed RRC UIC records, Texas Water Development Board records regarding formation waters, and Texas Society of Petroleum Engineers publications regarding formation water geochemistry to evaluate the potential source of the water.
Based on the laboratory analytical results, observations of pressure at select data points during the completion of investigation activities, site geology and the exposure of an artesian brine aquifer to the historic cable-tool production wells, a historic cable-tool well was identified as the likely source of contamination to the creek.
Geologic Unit Evaluation