Unconventional/complex reservoirs

Robust Integrated Approach Evaluates Heavy Sludge Formation

This work investigates the root cause of strong oil/water emulsion and if sludge formation is occurring within the reservoir using a robust integrated approach.

Fig. 1—SARA analysis before and after sludge issue.
Fig. 1—SARA analysis before and after sludge issue.
Source: SPE 219501.

In a field where sludge formation was not expected, an oil-producing well showed a sudden deterioration in well productivity. Extensive laboratory analysis indicated that sludge deposition was promoted by the presence of asphaltenes, resins, high amounts of calcium and sodium contents, and low-pH brine. The scope of this work was to investigate the root cause of strong oil/water emulsion and sludge issues of the AB oil field in Pakistan based on a robust integrated approach.

Field Overview

The AB field was discovered in December 2018 and was put into production in May 2019. The well is perforated in the Khewra sandstone reservoir, which is a four-way fault-bounded structure. The initial reservoir pressure of the field was 8,140 psia, with a reservoir temperature of 276.5°F. The reservoir has a strong aquifer drive mechanism with an API of 28°. At the beginning of the production, the water cut was low.

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