Babak Dehghani

Water produced in oil wells poses significant challenges, including increased operational costs and environmental risks. Accurate identification of associated water sources is critical for optimizing reservoir management and reducing operational costs. Traditional methods, which rely on single-variable analysis or isotopic measurements, are often complex, computationally intensive, region-specific, or ineffective for mixed-water scenarios. This study addresses these gaps by proposing a scalable scoring system that integrates nine key ionic parameters (e.g., Na⁺, Cl⁻, Mg²⁺, Ca²⁺, SO₄²⁻) and assigns dynamic weights to each parameter based on its diagnostic relevance. This study introduces a systematic scoring-based methodology to classify water origins into four categories: (1) in-situ formation water, (2) adjacent (neighboring) formation water, (3) drilling fluid contamination, and (4) acidizing operation fluids. Using ion-specific criteria and weighted scoring matrices, the method proposed a quantitative approach to interpreting water analysis data and translating into actionable decisions. Application of the method to three water samples from one of the Middle Eastern carbonate reservoirs revealed a transition from stimulation fluid dominance (score: 89.1) in the initial sample to formation water dominance (score:83.2) in the final sample. This highlights the methodology’s capability to differentiate fluid sources across samples with clear numerical support. The approach is practical, low cost and suitable for real-time field application without the need for advanced laboratory techniques.

Co-author/s:

Esmaeil Hamidpour, Senior Reservoir Engineer, National Iranian South Oil Company.