Formation water compositions are usually required for core studies undertaken on SCAL, formation damage and EOR projects.
But, formation water compositions may not be representative of those in the reservoir because they can be changed by many factors including: contamination (e.g. by drilling mud, use of incorrect preservatives, etc), sample cooling, sample de-pressurisation, sample de-gassing, exposure of the sample to air, use of inaccurate or inappropriate analytical methods, and erroneous reporting.
Use of an incorrect formation water composition can impact core study results, including:
- Clay swelling and fines mobilisation (induced damage studies).
- Use of incorrect salinity (resistivity/conductivity for Petrophysical SCAL studies).
- Incorrect viscosity (mobility ratio for reservoir engineering SCAL studies).
- Formation of mineral scale.
- EOR with polymer and surfactants need to be accurately matched to a correct formation water salinity.
- EOR by low salinity water flooding; de-risking the formation water composition is of profound importance.
Recently, we have been pleased to support Core Specialist Services Limited (CSS) by evaluating the quality of formation water compositions before they are used in core studies.
This work has involved (a) identification of uncertainties in these compositions arising from sampling and analysis conditions, (b) constraining/estimating more appropriate compositions where necessary, and (c) providing compositions that will be stable for laboratory studies.
The evaluations have been well received by CSS Clients and CSS are now offering this as a routine service option. Please see the CSS website for more details.
