Re: Request for Disposal of Cement Rinsate and Approved Non-Hazardous Fluids in North Cook Inlet Well 12-A
Ms. Shannon Donnelly
ConocoPhillips Alaska Inc.
P.O. Box 66
Kenai, AK 99611
Dear Ms. Donnelly:
By letter dated September 16, 2002, ConocoPhillips Alaska Inc., (“ConocoPhillips”) requested authorization to dispose of non-hazardous wastes, other than those wastes returned from downhole, into the North Cook Inlet Unit (NCIU) Well A-12 Class II disposal well. This well is located on the Tyonek platform, offshore in Cook Inlet. The wastes identified by ConocoPhillips would be generated during well work and drilling programs, and include excess cement slurry, cement rinsate, and small quantities of excess fluids associated with the proposed activities such as completions, well workover, testing and drilling. Your letter clarifies that a National Pollutant Discharge Elimination System permit for the Tyonek platform does authorize the discharge of these fluids directly into Cook Inlet with specific monitoring, record keeping, and reporting.
Our records indicate that NCIU Well A-12 passed a mechanical integrity test on November 8, 2001, as required in 20 AAC 25.252(d).
Provided with ConocoPhillips’ request were test results of an analogous cement rinsate, and the Material Safety Data Sheet (MSDS) for each proposed fluid to be injected. The request was further supplemented on September 27, 2002, with laboratory analysis of a representative sample of cement rinsate from Well B-2 at the Tyonek platform. Data provided by ConocoPhillips demonstrates that the fluids proposed for injection do not exhibit any hazardous characteristics as defined in 40 CFR 261.
The fluids noted in ConocoPhillips’ request are generated in primary field operations intrinsic to development activities intended to improve the ultimate recovery of oil and natural gas from the reservoir, to repair well integrity, or properly abandon those development wells that have no future utility. These fluids are consistent in composition with materials already authorized under Disposal Injection Order No. 17 and pose no risk of fluid movement into a USDW. The AOGCC also agrees with the assessment that underground injection into this Class II disposal well represents the environmentally preferable option for managing non-hazardous drilling and well service fluid on the Tyonek platform.
The Commission has determined that the fluids, as represented in ConocoPhillips’ request for administrative approval, namely excess cement slurry, cement rinsate, KCL water, CaCl2 brine, and excess water based mud are suitable for disposal in the NCIU Well A-12 as proposed. Approval applies only to this specific request and is not intended to provide for a blanket authorization to inject these or similar non-hazardous fluids down other Class II disposal wells.
DATED at Anchorage, Alaska and dated October 10, 2002.
Cammy Oechsli Taylor
Daniel T. Seamount, Jr.
Michael L. Bill, PE
BY ORDER OF THE COMMISSION