Summary
Scale control in deepwater oil and gas production is often challenging not
only because of the geological and mechanical limitations associated with
deepwater wells, but also because of the high-temperature (>150°C) and
high-pressure (>10,000 psi) (HT/HP) environment, which may be associated
with brine containing high total dissolved solids (TDSs) (> 300,000 mg/L).
These extreme conditions make scale prediction, control, and testing difficult
because of the requirements for special alloys, pumps, and control equipment
that are not readily available. Therefore, few reliable
ultrahigh-temperature/ultrahigh-pressure (ultra-HT/HP) data are available. To
overcome such challenges, an efficient flow-loop method has been established to
study both the equilibrium and the kinetics of scale formation and inhibition
at ultra-HT/HP conditions. This paper will discuss (1) an efficient flow-loop
method to study the solubility of scale minerals at ultra-HT/HP conditions, (2)
solubility of barite at temperature up to 200°C and pressure up to 20,000 psi,
and (3) scale control and inhibitor selection for deepwater oil and gas
production at ultra-HT/HP conditions. Specifically, the performance and thermal
stability of some common scale inhibitors at the high-temperature conditions
were studied in terms of barite-scale inhibition. The results to date indicated
that (1) the solubility of barite at up to 200°C and 24,000 psi can be measured
precisely by this newly developed flow-loop apparatus, (2) the rate of mineral
scale formation at HT/HP may be considerably faster than previously projected
from low-temperature studies and, hence, difficult to inhibit, (3) different
scale inhibitors have shown considerably different thermal stability. The
results and findings from these studies validate a new HT/HP apparatus for
scale and inhibitor testing and information for better scale control at HT/HP
conditions.
© 2012. Society of Petroleum Engineers
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History
- Original manuscript received:
7 February 2011
- Meeting paper published:
11 April 2011
- Revised manuscript received:
13 May 2011
- Manuscript approved:
6 June 2011
- Published online:
16 January 2012
- Version of record:
13 March 2012
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