The formation of calcium carbonate mineral scale is a persistent and expensive problem in oil and gas
production, especially in the high temperature and high pressure (HTHP) wells. Scaling of metallic or
insulating walls in contact with hard water may cause unscheduled equipment shutdown and loss of
production. The aim of this paper is to develop environmentally friendly calcium carbonate scale
inhibitors for HTHP squeeze application in the oil and gas field water treatment.
Typical commercial scale inhibitors, including several phosphonate based squeeze scale inhibitors and
patented environmentally friendly polyacrylic copolymers have been tested based on thermally stability
test, formation water compatibility test, dynamic scale loop test and coreflood test.
In this paper, an environmentally friendly calcium carbonate scale inhibitor has been developed to
inhibit calcium carbonate scale deposition effectively under HTHP conditions. The characteristics of this
product are as following:
- Thermally stable at high temperature
- Excellent calcium tolerance at high temperature
- Good inhibition performance on CaCO3 deposition at high temperature
- Long squeeze life and no formation damage based on coreflood test
- Environmentally friendly
- Easy residual analysis by ICP, HPLC and hyamine methods
This paper will give a comprehensive study of developing environmentally friendly calcium carbonate
scale inhibitors for squeeze application for HTHP wells in the oil and gas fields, which includes
thermally stability, dynamic scale loop performance, adsorption and desorption performance,
compatibility, residual analysis and environmental regulation.
Key words: calcium carbonate, inhibitor, scale, HTHP well