API RP 90:2006 pdf download

API RP 90:2006 pdf download.Annular Casing Pressure Management for Offshore Wells.
An acceptable level of risk caused by annular casing pressure is established in this Recommended Practice by three parameters. First, wells that exhibit 1(X) psig or less of annular casing pressure present little risk and should just be monitored. Second, annular casing pressure greater than 100 psig that has been diagnosed as S(’P must bleed to iem psig. SC? that will bleed to zero psig presents an acceptable risk to personnel, property and the environment, since it indicates that the leak rate is small and the harriers to flow are still effective. The third parameter establishes a Maximum Allowable Wellhead Operating Pressure (MAWOP). in which the maximum annular pressure allowed on the annulus is determined. The MAWOP calculation is applicable to SCP. thermal casing pressure and operator-imposed casing pressures. The establishment of the MAW()P for an annulus presents an acceptable risk posed by annular pressure to personnel. property and the environment since it minimizes the risk of burst or collapse of the tuhulars.
If the annular casing pressure does not meet the criteria established by the three parameters discussed above, this does not mean that the risk presented by the annular pressure is unacceptable. Rather, it indicates that the annular casing pressure needs to be managed on a case-by-case basis that goes beyond the scope of this Recommended Practice. The case-by-case management of annular casing pressure may include the use of risk assessment techniques, which are discussed in Section 10 of this Recommended Practice.
Appendix A of this document contains simple flow charts of the annular casing pressure management prorani. as well as examples for each well type.
4 Maximum Allowable Wellhead Operating Pressure (MAWOP)
The Maximum Allowable Wellhead Operating Pressure(MAWOP). as defined in 1.3, is a measure of how much pressure can be safely applied to an annulus and is applicable to all types of annular pressure. including thermal casing pressure. SUP and operator-imposed pressure. l’he MAWOP is measured relative to the ambient pressure a the wellhead for any paflicular annulus. ft establishes a safety margin in consideration of the following failure modes:
• Collapse of the inner tubular. Burst of the outer tubular.
The MAWOP 11w the annulus being evaluated is the lesser of the ftllowing:
• 50 Percent of the Minimum Internal Yield Pressure of the pipe body for the casing or production riser siring being evaluated: or
• t0 percent of the Mininitim Internal Yield Pressure of the pipe body of the next outer casing or production riser siring: or
• 75 percent of the Minimum Collapse Pressure of the inner tubular pipe body.
For the last casing or production riser string in the well, the MAWOP is the lesser of the following:
• 30 percent of the Minimum Internal Yield Pressure of the pipe body for the casing or production riser string being evalu
ated: or
• 75 percent of the Minimum Collapse Pressure of the inner tubular pipe body.