Mineral scale formation and deposition on downhole and surface equipment is a major source of cost and reduced production to the oil industry.This paper describes a novel semi-quantitative kinetic approach to predicting the location of barium sulfate formation and deposition.The key conclusions of this work are:
There is probably negligible formation damage arising from barium sulfate deposition in the near well bore region.
There are three kinds of barium sulfate precipitation in the well depending upon the scaling tendency (saturation ratio) in the produced brine (it is assumed that the higher saturation ratio values for barite at the bottom of the well is a consequence of mixing of high sulfate brine from sea water breakthrough with high barium brine formation water). The location of the scale formation can be predicted from knowledge of the nucleation induction time coupled with mass transfer arguments. The equations describing these have been developed in this paper and applied to some general illustrative cases demonstrating the applicability of the approach. In particular, a method has been developed for predicting the location of scale formation and deposition at low saturation ratios such as developed when sulfate-removal is utilized as a barite scale control technology.