Technical review verifies that the proposed injection well meets construction and operation standards for groundwater protection and confinement of injected fluids.
- Permit Restrictions by Geography and Geology
- Surface Casing
- Production Casing
- Packer Depth
- Geologic Isolation
- Area of Review
- Injection Pressure
- Injection Fluids
- Commercial Facilities
- Dual Completion Wells
- Horizontal Injection Wells
- Rule Exceptions
- Engineering and Geological Studies
The surface casing review verifies that groundwater is adequately protected.
- For new wells, surface casing must be set to the protection depth determined by the Groundwater Advisory Unit of the Railroad Commission of Texas and cemented to the surface. For cementing details, see this figure or Statewide Rule 13. UIC staff will not administratively approve a permit with exceptions to Statewide Rule 13 (b)(1) for wells that are to be drilled for injection or disposal purposes.
- Cementing the long-string casing from total depth to the surface instead of setting surface casing will not be administratively approved with proof of good cause.
- Statewide Rule 13 (a)(3)(B) states:” For subsequent casing strings, the diameter for each section of the well bore for which casing will be set and cemented shall be at least one (1) inch greater than the nominal outside diameter of the casing to be installed, unless otherwise approved by the district director."
- Proposals to convert existing wells with short surface casing or single string completions will be considered on a case-by-case basis. If approved, permits for existing wells with short surface casing may require additional safeguards such as remedial cementing, annual pressure testing, and/or annulus pressure monitoring. Commercial disposal wells with short surface casing will not be administratively approved.
The production casing review verifies that the production casing is adequately cemented in accordance with Statewide Rule 13 to confine injected fluids to the proposed injection zone.
- The production casing must be cemented immediately above the injection/disposal interval with at least:
- 600 feet of cement based on cement volume calculations,
- 250 feet of cement verified by a temperature survey conducted at the time of cementing, or
- 100 feet of cement verified by a cement bond log that shows the cement is well bonded to the pipe and formation (80% bond or higher) with no indication of channeling; or
- If the well was spudded prior to January 1, 2014, 500 feet of cement based on cement volume calculations.
- When evaluating top of cement calculations, UIC staff assumes Class A cement with no volume extenders (unless the application indicates otherwise) and a washout factor of 30% along the gulf coast and 20% inland.
- In the absence of cementing records, the casing will be presumed to be un-cemented and the applicant will be required to file a cement bond log to demonstrate the adequacy of existing cement or perform a cement squeeze.
- Cement bond logs must contain a cement bond amplitude curve, an amplified cement bond curve, a transit/travel time curve, and a variable density/sonic waveform display.
Packer depth review verifies that the proposed packer setting depth is in accordance with Statewide Rules 9 or 46 and will keep injected fluids confined to the proposed injection interval.
- Disposal wells permitted under Rule 9 (Form W-14) must have a packer set within 100 feet of the permitted disposal interval.
- Injection/disposal wells permitted under Statewide Rules 46 and 96 (Form H-1) must have a packer set no higher than 200 feet below the known top of cement behind the production casing and at least 150 feet below the base of usable quality water. If there are potentially permeable zones between the proposed packer setting depth and the proposed injection interval, the packer must be set below those zones or the application must be amended to include those zones in the proposed injection interval. As a practical matter, staff will direct applicants to specify a packer setting depth within 100 feet of the top of the permitted interval.
Geologic isolation review verifies that the proposed injection well will not contaminate freshwater and that fluids injected will be confined to the injection interval.
- The authorized injection or disposal intervals must be isolated from usable-quality water strata 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, and be adequately separated from Underground Sources of Drinking Water (USDW).
- This diagram shows the primary geologic isolation criteria UIC and GAU staff use. If the proposed injection/disposal well does not meet the primary criteria for geologic isolation, additional information may be necessary to demonstrate protection of freshwater or the permit may not be administratively approved.
- Injection into aquifers that contain water less than 10,000 mg/L total dissolved solids will not be authorized unless those aquifers have been exempted. For injection wells injecting into an exempted aquifer, injection fluids may be limited by permit condition to waters produced from the same productive formation as the injection interval and from wells on the same lease ("Fluid Source Limit").
- Both Statewide Rules 9 and 46, as well as the permit itself, require that injected fluids be confined to the authorized injection interval, which is the depth interval stated in the application and resulting permit. The entire formation or reservoir is not authorized for injection unless the stipulated depth intervals correspond to the entire formation or reservoir.
This Area of Review verifies that all wells within the AOR are adequately plugged to ensure that injected fluid are confined to the proposed injection zone.
- All abandoned wells within a 1/4-mile radius must have been plugged in a manner that will prevent movement of fluids from one zone to another and protect freshwater.
- The applicant may show by calculation that a lesser area will be affected by pressure increases to justify using the lesser area in lieu of the 1/4-mile radius. These calculations must be performed by, and bear the seal of a professional engineer registered in the State of Texas.
- Shallow disposal in the Barnett Shale area (shallower than the Barnett Shale) of North central Texas is required to show that all wells within a 1/2-mile radius have been adequately plugged or cemented across the disposal interval and to perform reservoir pressure increase calculations because of bradenhead pressure buildup problems in the area.
- The area of Review does not stop at the Texas state line. If the AOR extends into an adjoining state, UIC staff will require that the adjoining state UIC program staff be notified of the permit application.
- If no plugging reports are found then you can submit drilling logs or other records accepted by RRC to show the wells total depths do not penetrate the subject well permitted interval.
- If RRC plugging records are not readily available for any plugged wells, include copies of the best available information to demonstrate that the wells have been plugged. UIC Staff will determine the adequacy of these records to demonstrate the well is plugged.
- If no plugging records can be found, you may re-enter and plug these wells in accordance with Statewide Rule 14. If this is your intent, provide a statement of your proposal to plug or a copy of Form W-3A Intent to Plug.
- For injection wells for secondary or enhanced recovery, if records are unavailable at the District or Austin Offices of the Railroad Commission or indicate that the wells do not contain cement plugs between the injection interval and the base of usable-quality water, you must demonstrate by computations or other means that the “unknown status” wells fall outside area than the area that will be affected by pressure increases caused by injection. The deepest depth of the USDW must be used in these calculations. Then, this distance may then be used in lieu of the 1/4-mile radius AOR in accordance with Statewide Rule 46. If submitted, these calculations must be performed by and bear the seal of a professional engineer registered in the State of Texas.
Injection pressure review verifies that the proposed injection pressure does not exceed the formation fracture gradient and that the existing casing cement is adequate to ensure that injected fluids are confined to the proposed injection zone.
- The permitted pressure will not exceed 1/2 psi per foot of depth to the top of the injection/disposal interval, unless the results of a fracture pressure step-rate test support a higher pressure.
- Generally, the maximum surface injection pressure will be the pressure requested in the application or 1/2 psi per foot of depth to the top of the injection/disposal interval, whichever is less.
- Shallow (2,000 feet or less) disposal along the Gulf coast is further limited to 1/4 psi per foot of depth because of low fracture gradients in the coastal sediments.
- Shallow disposal in the Barnet Shale area (shallower than the Barnett Shale) of North central Texas is further limited to 1/4 psi per foot of depth because of bradenhead pressure buildup problems in the area.
Injection fluids review verifies that the fluids proposed for injection are for recovery of oil or gas or are oil and gas exploration production wastes. Only these wastes may be disposed into UIC Class II injection wells under the Railroad Commission's jurisdiction.
- The permit will be limited to the injection of produced salt water unless the application specifically lists other fluids to be injected.
- If the application proposed injection of fresh water for recovery of oil or gas, the applicant must show that there is no economically or technically feasible alternative to the use of fresh water as an injection fluid.
- Statewide Rules 9 and 46, define a "commercial well" is a well whose owner or operator receives compensation from others for the disposal of oil field fluids or oil and gas wastes that are wholly or partially trucked or hauled to the well, and the primary business purpose for the well is to provide these services for compensation.
- Special surface facility provisions will be included in the permit for a commercial well. These provisions include requirements for spill prevention and containment, pit permitting, and site security.
- The Commission requires that the provisions set out below be included in commercial disposal well and fluid injection well permits. These provisions are designed to prevent pollution from activities associated with the surface facilities.
Surface Facility Requirements
- Prior to beginning operation, all collecting pits, skimming pits, or washout pits must be permitted under the requirements of Statewide Rule 8.
- Prior to beginning operation, a catch basin constructed of concrete, steel, or fiberglass must be installed to catch oil and gas waste which may spill as a result of connecting and disconnecting hoses or other apparatus while transferring oil and gas waste from tank trucks to the disposal facility.
- Prior to beginning operation, all fabricated waste storage and pretreatment facilities (tanks, separators, or flow lines) must be constructed of steel, concrete, fiberglass, or other materials approved by the Assistant Director of Technical Permitting. These facilities must be maintained so as to prevent discharges of oil and gas waste.
- Prior to beginning operation, dikes shall be placed around all waste storage, pretreatment, or disposal facilities. The dikes shall be designed so as to be able to contain a volume equal to the maximum holding capacity of all such facilities. Any liquids or wastes that do accumulate in the containment area shall be removed within 24 hours and disposed of in an authorized disposal facility.
- Prior to beginning operation, the facility shall have security to prevent unauthorized access. Access shall be secured by a 24-hour attendant, a fence and locked gate when unattended, or a key-controlled access system. For a facility without a 24-hour attendant, fencing shall be required unless terrain or vegetation prevents truck access except through entrances with lockable gates.
- Prior to beginning operation, each storage tank shall be equipped with a device (visual gauge or alarm) to alert drivers when each tank is within 130 barrels from being full.
- If the facility will have staff on-site for periods of time necessitating bathroom accommodations, these accommodations must be designed, installed, and maintained by a person licensed to do so and the accommodations must comply with all applicable local, county, and State health regulations.
- The permit application must clearly indicate that the well will be a dual completion and identify the production and injection intervals.
- Standard permit conditions do not allow any perforations outside the permitted injection interval.
- Appropriate mechanical integrity testing and monitoring conditions will be added to the permit.
- Technical discussion of Dual Completion Well issues
Mechanical Integrity Test
The most common mechanical integrity testing procedure for productive perforations in the tubing-casing annulus, is as follows:
- Pull the tubing and packer string(s) from the well.
- Set a temporary plug within 100 feet of the injection perforations.
- Run a test packer on tubing and set it just below the productive perforations.
- Perform a standard H-5 pressure test of the casing between the test packer and temporary plug (above perforations).
- Reset the test packer just above the productive perforations.
- Perform a standard H-5 pressure test of the annulus to test the casing from the test packer to the wellhead.
- Pull the tubing, test packer, and temporary plug, and then reset the injection string.
- Perform a radioactive tracer survey through the injection string to demonstrate tubing integrity and packer seal.
- File the Pressure Test Reports (Forms H-5) for each of the three parts of the mechanical integrity test.
- Notification must indicate that the well includes a horizontal segment and must include a plat showing the direction and extent of the horizontal segment.
- The Area Of Review will be a 1/4-mile radius along the horizontal segment (or geometric stadium).
- Measured depths and true vertical depths are required to be annotated on the application as applicable (for example, total depth, injection interval, packer depth).
- A wellbore sketch must be attached to the application.
- Appropriate mechanical integrity testing and monitoring conditions may be added to the permit.
UIC staff will grant exceptions to the rule-required well construction standards only for good cause and when the proposed completion maintains the safety factor for groundwater protection and confinement of injected fluids.
Tubing and Packer Exception (Injection Down Casing)
An exception to the tubing and packer rule requirement may be considered for certain types of low-risk wells that exceed the rule specified well construction standard.
- A conventional tubing and packer completion is not feasible.
- Surface casing must be cemented through the entire zone of usable quality ground water, and production casing cemented from total depth to surface. Both strings of casing have good mechanical integrity. Casing that has failed an MIT does not count as one of the two strings cemented from total depth to surface until it is repaired and passes an H-5 pressure test. Cement behind both strings of casing must meet cement quality requirements of Statewide Rule 13.
- The well can operate at low injection pressure (500 psi or less) and low injection volume (500 bbls/day or less).
- Wells that are approved for casing injection will be required to perform a casing pressure test against a temporary packer/plug to demonstrate mechanical Integrity of the long string casing at least annually.
Packer Depth Exception
An exception to the packer setting depth requirement (which allows the packer to be farther uphole from injection zone) can be considered only if confinement of injected fluids to the authorized injection zone can be ensured.
- Packer must be set opposite cemented casing, with adequate cement above the packer.
- There must be at least 250 feet of clay/shale between the packer depth and usable-quality water.
- There are no productive horizons or potential disposal zones between packer depth and injection zone.
- There is no indication of casing leaks below packer.
- The permit may be issued with an additional radioactive tracer survey requirement to demonstrate mechanical integrity of the casing between the packer and permit zone.
- The packer setting depth requirements of Statewide Rule 46 (Forms H-1 and H-1A) allows greater flexibility in packer setting depths.
- The packer depth proposed in the application is reviewed for the presence of potential zones between the packer and permitted injection zone. If any potential zones are found, the packer depth will be rejected. In this case, the packer must be lowered or the permitted zone must be raised to include the potential zone.
- Moving the packer up hole after the permit is issued will likely result in subsequent mechanical integrity tests being ruled inconclusive unless a completion report was properly filed with the Commission.
Pressure Observation Valve Exception
Rule 9, 46 and 96 require that wells to be equipped with wellhead pressure observation valves on the tubing and each annulus. An exception to the observation valve requirement can be considered only if confinement of injected fluids to the authorized injection zone can be ensured. An exception is not required if the subject annulus is fully cemented to ground surface.
- There are no over-pressured formations in the area.
- There are no bradenhead pressure problems in the area.
- Exception approval requires more frequent mechanical integrity testing and/or monitoring.
The practice of engineering is regulated by the Texas Occupations Code, Title 6, Chapter 1001. Any engineering work product required for the permit application must be performed by a licensed Professional Engineer. For example:
- Pressure front calculations which may be performed for the Area of Review.
- Closure cost estimates for pits associated with commercial disposal well operations under Statewide Rule 78.
- Check the Texas Board of Professional Engineers website for other situations requiring an Professional Engineer's seal.
The practice of geology is regulated by the Texas Occupations Code, Title 6, Chapter 1002. Any geological work product required for the permit application must be performed by a licensed Professional Geoscientist. For example:
- Well log formation correlation and analysis which may be performed for the Area of Review.
- Well log interpretation for geologic isolation from freshwater, effective reservoir thickness, etc.
- Check the Texas Board of Professional Geoscientists website for other situations requiring a Professional Geoscientist's seal.