Chemical additives used in hydraulic fracturing fluids in North American basins need to minimize formation damage and mobilize hydrocarbons to enhance recovery factors. A multi-parametric selection methodology allows chemical effectiveness optimization on a well-specific basis.  The role of chemical treatments on minimizing mineral/fluid sensitivities and maximizing hydrocarbon mobility is presented.  Efficacy-based production responses are compared for specific regions.<br/>Drilled cuttings acquired from unconventional reservoirs were characterized using X-ray diffraction, cation exchange capacity (CEC), swelling sensitivity testing (SST), and mechanical stability turbidity (MST) testing to determine mineralogy and fluid sensitivity. Respective formation oils were analyzed by API gravity, SARA (saturates, aromatics, resins, asphaltenes) and emulsion tendency. Various chemical additives effects were evaluated to remediate specific damage mechanisms and their impact on production data and oil recovery factors is compared.<br/>The research indicates that North American formation oils have an average colloidal instability index of 2.6 (problematic greater than 0.9), and formation materials have an average CEC of 9, indicating moderate fluid sensitivity. The classifications suggest that an average well would have low hydrocarbon mobility and exhibit fluid induced formation damage without chemical treatments. Formation minerals were evaluated with various treatments to reveal that cationic charge and concentration determine the efficacy of preventing clay swelling damage. However, molecular weight and chemical functionality drive permanency and remediation of fines generation. Surfactants above their CMC increase the mobility of hydrocarbons and those that induced a weak emulsion had the most effect on mobilizing the hydrocarbons. Comparison of well production data reveals an increase in barrel of oil equivalent (BOE) over the life of the well for those wells stimulated with optimized chemical treatments, over offsets in the same region.

Using custom chemistry to design optimal stimulation treatment fluids to potentially improve hydrocarbon recovery factors

254th National Meeting (2017)

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