Standards and Procedures for Class II Wells
Under Statewide Rules 9, 46, 95, 96, and 97, operators of injection and disposal wells associated with oil and gas exploration, production, transportation, or underground storage Class II wells must obtain a permit from the Railroad Commission. Thus, all Class II wells in Texas must be approved by the Commission before injection operations can legally begin. Pursuant to Rules 9, 46, 95, 96, and 97, and the applicable application forms, such permits will be approved only if the applicant satisfies the burden of showing that fresh water will be protected.
Once a permit is granted, the operator is bound by all applicable Commission rules and permit conditions by virtue of accepting the right to operate pursuant to the permit. It is necessary to examine permit conditions, as well as statewide rules, in order to determine what actions are necessary for compliance.
Types of Permits
Permits to dispose of salt water or other oil and gas wastes by injection into porous formations that are not productive of oil, gas, or geothermal resources are issued under Statewide Rule 9. Form W-14 is used to apply for this type of permit.
Permits to inject water, steam, gas, oil and gas wastes, or other fluids into porous formations that are productive of oil, gas, or geothermal resources are issued under Statewide Rule 46. Forms H-1 and H-1A are used to apply for this type of permit.
Permits to conduct hydrocarbon storage operations are issued under Statewide Rules 95, 96, or 97. Form H-4 is used to apply for permits issued under Rules 95 and 97. Form H-1/H-1A is used to apply for permits issued under Rule 96.
Commercial Disposal Wells
A commercial disposal well is a well whose owner or operator receives compensation from others for the disposal of oilfield fluids or other oil and gas wastes that are wholly or partially trucked to the well and the primary business purpose of the well is to provide these services for compensation. Permits for commercial disposal wells contain special conditions for surface facilities associated with waste management.
All permit applications for Class II wells come to the Technical Permittin Section, where they are evaluated and processed. If a hearing is requested or required, the Technical Permitting Section requests that a hearing be scheduled, and the Commission provides notice to all interested persons. After the hearing, the examiners recommend final action to the Commissioners, who decide if the permit will be issued. If no protests are received on an application, the Director of Technical Permitting may administratively approve the application.
See the section titled "Injection and Disposal Well Permitting" for more detail on permitting standards and procedures.
Transfer and Modification of Permit
An injection or disposal well permit may be transferred only after notice to the Commission. Written notice of intent to transfer the permit must be submitted to the Commission on Form P-4 at least 15 days prior to the date the operators plan for the transfer to occur. Permit transfer will not occur until the Form P-4 has been approved by the Commission.
An injection or disposal well permit may be terminated, suspended, or modified for just cause, such as a substantial change in well completion or operation, pollution of fresh water, substantial violations of permit conditions or rules, misrepresentations by the applicant, or the escape of injected fluids from the authorized zone. Notice and opportunity for hearing are provided in the same manner as in the initial permit process.
The authorized injection or disposal strata must be isolated from overlying usable quality water by a sufficient thickness of relatively impermeable strata, which is generally considered to be an accumulative total of at least 250 feet of clay or shale. Variances in the total thickness required are considered on the basis of continuity of strata, thickness of individual strata, or the presence of relatively impermeable strata other than clay or shale. No injection or disposal well will be permitted where faults, fractures, structure, or other geologic factors indicate that isolation of the authorized injection or disposal zone is jeopardized. The operator must submit adequate geological information to show compliance with this requirement.
Casing and Cementing
Injection and disposal wells must be cased and cemented in accordance with Statewide Rule 13 to prevent the movement of fluids into sources of fresh water. Rule 13 requires that surface casing be set and cemented to protect fresh water strata, as defined by the Railroad Commission's Groundwater Advisory Unit (GAU). Cement is required to be circulated to the surface by the pump and plug method, and the specifications for cement quality and casing integrity set out in the rule must be met.
Injection and disposal wells must also meet criteria for adequacy of cement to confine injected fluids. These criteria are 100 feet of well bonded cement as determined by a bond log, 250 feet of cement as evidenced by a temperature survey, or 400 to 600 feet of cement as determined by a slurry yield calculation. The flexibility in calculated annular footage allows for consideration of the operating conditions, type of cement used, and characteristics of the formation.
Wells that are converted from producers to injection into the same productive formation usually meet cementing requirements if they were completed in compliance with Rule 13.
Area of Review
Statewide rules require that an applicant for an injection or disposal well permit examine the data of record for wells that penetrate the proposed injection zone within a one quarter (1/4) mile radius of the proposed well to determine if all abandoned wells have been plugged in a manner that will prevent the movement of fluids into strata other than the authorized injection or disposal zone. A permit applicant must submit a map showing the location of all wells of public record within 1/4 mile as part of the permit application. For those wells that penetrate the top of the injection or disposal zone, the applicant must attach a tabulation of the wells showing the dates the wells were drilled and the present status of the wells. Alternatively, if the applicant can show, by computation, that a lesser area will be affected by pressure increases, then the lesser area may be used in lieu of the fixed radius. In addition, an applicant may seek a variance from the Area of Review requirements by demonstrating that no significant increase in risk of groundwater contamination will result from the variance. No permit will be issued where the information submitted indicates that fresh water resources will be endangered unless permit conditions require appropriate corrective action in the area (e.g. remedial cementing, re-plugging inadequately plugged area wells, or more frequent testing and monitoring).
Standard Equipment Requirements
All newly drilled or converted injection wells permitted under Rule 46 and all disposal wells permitted under Rule 9 must be equipped with tubing set on a mechanical packer unless an exception is granted by the director for good cause. Pressure observation valves are required on the tubing and each annulus.
Maximum injection pressure limitations have been part of the Commission's permitting program for many years and continue to be required as a condition of each injection or disposal well permit. Pressure limitations are established to provide adequate assurance that injection will not initiate fractures in the confining zones. The maximum surface injection pressure may not ordinarily exceed 1/2 psi per foot of depth to the top of the authorized injection or disposal interval. A fracture pressure step-rate test must be performed to justify a higher pressure.
Monitoring and Reporting
The operator of each injection or disposal well is required by the statewide rules to monitor the injection pressure and volume on a monthly basis and to report the results annually on Form H-10. Any downhole problem that indicates the presence of leaks in the well must be reported to the appropriate district office within twenty-four (24) hours.
See the section titled "Injection and Disposal Well Monitoring" for more detail on monitoring requirements.
All injection and disposal wells must be pressure tested before injection operations begin, after any workover that disturbs the seal between the tubing, packer, and casing, and at least once every five (5) years to determine if leaks exist in the tubing, packer, or casing. Some permits require more frequent tests, such as annual pressure tests for converted wells with short surface casing. The appropriate district office must be notified before any pressure test to allow a Commission representative to witness the test. The operator must then file a record of the test with the district office (Form H-5) within 30 days of the test. As an alternative to the five-year pressure testing, the operator may monitor the casing-tubing annulus pressure and report the results annually if the reported information demonstrates mechanical integrity and provided that the well is pressure tested at least once every ten (10) years.
Wells not equipped with tubing and packer or with other non-standard completions may require special down hole surveys to demonstrate mechanical integrity. These surveys must be approved in advance for a specific wellbore by Technical Permitting in Austin unless they are expressly required by the injection/disposal well permit.
See the section titled "Injection and Disposal Well Mechanical Integrity Testing" for more detail on mechanical integrity testing requirements.
A completion report (Form W-2 or G-1) must be filed with the appropriate district office within thirty (30) days of completion or conversion to disposal or injection to reflect the new or current completion.
The statewide rules allow the director to grant exceptions to tubing and packer, packer setting depth, and pressure observation valve requirements of the rules upon proof of good cause.
In addition, the district office may grant an exception to the surface casing requirements of Statewide Rule 13 and authorize use of the multistage completion process. Multistage cementing (in lieu of setting surface casing) is not normally authorized as a means to protect fresh water strata for wells drilled expressly as injection or disposal wells.
Plugging and Abandonment
All injection and disposal wells are required to be plugged upon abandonment, in accordance with Statewide Rule 14. A notice of intention to plug and abandon (Form W-3A) must be filed with the appropriate district office and received five (5) days prior to the beginning of plugging operations. Plugging operations may not begin prior to the date shown on the Form W-3A unless authorized by the District Director.
The general requirements of Rule 14 ensure the protection of all formations bearing fresh groundwater, oil, gas, or geothermal resources. Each well is also subject to the specific requirements of Rule 14 that are applicable to the particular well completion situation. Special plugging requirements that are specific to the well, field, or area may apply at the discretion of the District Director.
Within thirty (30) days after a well is plugged, a complete record (Form W-3) must be filed in duplicate with the appropriate district office.