Re-Visit Impact of High Temperature Conditions >150 °C on Sulphate Scale Dissolver Performance

摘要

Scale issues are expected in new ultra HPHT (high pressure high temperature) fields. Scale dissolvers are the essential part of scale management. Using chemicals to treat scale deposition is regarded as much safer and more cost effective than physical removal. Unexpected significant performance decline of BaSO4scale dissolver at 176 °C was reported in 2014 SPE scale conference in Aberdeen (reference 1). 2014 paper suggested a temperature limit (< 176 °C) on effective removal of sulphate scales, although thermal degradation of chemicals was ruled out. This paper reports BaSO4 dissolver test results at different temperatures with chemicals from multiple chemical suppliers, in an effort to identify workable scale treatment chemicals for HT fields. Repeated tests, with varied test procedures, revealed that suggested temperature limit (<176 °C) did not exist. Enhanced sulphate scale dissolution at increased system temperature was observed. Impact of chemical nature and application conditions on dissolution capacity and rates will be presented. Potassium salt of DTPA chemical at high pH is most effective in removal of BaSO4 scales. Different test processes and test results will be discussed. Introduction