Unlocking Commingled Production Using Geochemical Production Allocation

In Ecuador commingled production is being used as a strategy to fulfill the government's objective of increasing production. A key challenge in commingled production is how efficiently quantify the contribution of individual reservoirs to support production allocation to the zones meeting the regulation requirement. Geochemical fingerprinting is a fast, viable, and cost-efficient method for production back-allocation. The application has been successfully applied and technically validated for the first time in Ecuador, opening a vast business opportunity. The feasibility, testing and implementation in a major field is covered in this paper. The geochemical allocation method compares the oil fluid composition of representative samples acquired from each reservoir (end members). The method seeks sufficient compositional information at zone level to calculate the zone contributions from the commingled well production composition. This analysis requires high-resolution gas chromatography and geochemistry interpretation, supported by a specialized software. A production allocation feasibility study was conducted initially to define if end members collected from seven reservoirs in 17 fields could be differentiated in mixtures based on a chemical distance analysis. The chemical distance analysis shows that oils from some reservoirs are very distinctive, while others are very similar, indistinguishable from each other. One advantage is that the sensitivity of the geochemical analysis allows the differentiation of even the very similar oils in mixtures, enabling the calculation of end-member contributions. Production was back-allocated in the commingled wells and was compared with the results obtained by traditional production logging tool (PLT) measurements in a cross-validated case study. The technology was successfully validated against traditional approaches such as PLT. The outstanding results show 2% difference between the technologies, which resulted in the approval by the client and raised the interest of the Ecuadorian regulation entity to use this technology as a complementary tool of the traditional technologies. The cost of the proposed alternative represents about 5% of the frequently used methods price. Therefore, all the existing commingled wells in the oilfield are frequently monitored using geochemical production allocation without impacting the oil production. Commingled production has maximized the field value by increasing production revenue while optimizing costs.