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Packer standards and classifications
The International Organization for Standardization (ISO) and the American Petroleum Institute(API) have created a standard [reference ISO 14310:2001(E) and API Specification 11D1] intended to establish guidelines for both manufacturers and end users in the selection, manufacture, design, and laboratory testing of the many types of packers available on today’s market. Perhaps more importantly, the standards also establish a minimum set of parameters with which the manufacturer must comply to claim conformity. The International Standard is structured with the requirements for both quality control and design verification in tiered rankings. There are three grades, or levels, established for quality control and six grades (plus one special grade) for design verification.
ISO/API standard grades
The quality standards range from grade Q3 to Q1, with grade Q3 carrying the minimum requirements and Q1 outlining the highest level of inspection and manufacturing verification procedures. Provisions are also established to allow the end user to modify the quality plans to meet his specific application by including additional needs as “supplement requirements.”
The six standard design-validation grades range from V6 to V1. V6 is the lowest grade, and V1 represents the highest level of testing. A special V0 grade was included to meet special acceptance criteria requirements. The following is a brief summary outlining the basic requirements of the various levels of test-acceptance criteria.
Grade V6 supplier/manufacturer defined
This is the lowest grade established. The performance level in this instance is defined by the manufacturer for products that do not meet the testing criteria found in grades V0 through V5.
Grade V5 liquid test
In this grade, the packer must be set in the maximum inner diameter (ID) casing it is rated for at the maximum recommended operating temperature. The testing parameters require that it be set with the minimum packoff force or pressure as specified by the manufacturer. The pressure test is performed with water or hydraulic oil to the maximum differential-pressure rating of the packer. Two pressure reversals across the tool are required, meaning it must be proved that the packer will hold pressure from both above and below. The hold periods for each test are required to be a minimum of 15 minutes long. At the end of the test, retrievable packers must be able to be removed from the test fixture by using the procedures of its intended design.
Grade V4 liquid test + axial loads
In this grade, all parameters covered in Grade V5 apply. In addition to passing V5 criteria, it also must be proved that the packer will hold differential pressure in combination with compression and tensile loads, as advertised in the manufacturer’s performance envelope.
Grade V3 liquid test + axial loads + temperature cycling
All test criteria mandated in Grade V4 apply to V3. To achieve V3 certification, the packer also must pass a temperature cycle test. In the temperature cycle test, the packer must hold the maximum specified pressure at the upper and lower temperature limits in which the packer is designed to work. The test is started at maximum temperature, as in V4 and V5. After passing this segment of the test, the temperature is allowed to cool to the minimum, and another pressure test is applied. After successfully passing the low-temperature test, the packer also must pass a differential-pressure hold after the test-cell temperature is raised back to the maximum temperature.
Grade V2 gas test + axial loads
The same test parameters used in V4 apply to Grade V2, but the test medium is replaced with air or nitrogen. A leak rate of 20 cm3 of gas over the hold period is acceptable, however, the rate may not increase during the hold period.
Grade V1 gas test + axial loads + temperature cycling
The same test parameters used in V3 apply to Grade V1, but the test medium is replaced with air or nitrogen. Similar to the V2 test, a leak rate of 20 cm3 of gas over the hold period is acceptable, and the rate may not increase during the hold period.
Special Grade V0 Gas Test + Axial Loads +Temperature Cycling + Bubble Tight Gas Seal This is a special validation grade that is added to meet customer specifications in which a tight-gas seal is required. The test parameters are the same as those for V1, but a gas-leak rate is not allowed during the hold period.
If a packer is qualified for use in a higher grade, it may be deemed suitable for use in any of the lower validation grades. For example, if tested to grade V4, it is accepted that the packer meets or exceeds the service requirements of V4, V5, and V6 applications.
- Intl. Std., ISO 14310, Petroleum and Natural Gas Industries—Downhole Equipment—Packers and Bridge Plugs, first edition. Ref. ISO 14310:2001 (E),(2001-12-01).
- API Specification 11D1, Petroleum and Natural Gas Industries—Downhole Equipment—Packers and Bridge Plugs, first edition. 2002. ISO 14310:2001.
Noteworthy papers in OnePetro
Allen, T. and Roberts, A.P. 1993. Production Operations, fourth edition, I and II.
Factors and Conditions Which Cause Seal Assemblies Used in Downhole Enviornments to Get Stuck. Baker Oil Tools—Engineering Tech Data Paper No. CS007.
Patton, L.D. and Abbott, W.A. 1985. Well Completions and Workovers: The Systems Approach, second edition, 57–67. Dallas: Energy Publications.