Robust Clay Stabilizer to Control Swelling in a Rich Swellable Clay Formation: A Laboratory Study

Abstract

The Gulf of Suez includes good source rocks for hydrocarbon generation; the Sinai field-Abu Rudeis base is the most important and largest producing field in this area. This formation represents the most challenging case study with significant amount of clays that affect the hydrocarbon production. A clay stabilizer additive was introduced during a workover operation and was determined to provide promising results. These results include better fines migration and prevention of swelling and migration while leaving formation and fluid properties unchanged. As with all clay stabilization products, a critical factor for treatment success is providing protection against clay swelling. Most gas wells in North Africa formations contain freshwater-sensitive clay minerals, including those found in shale streaks and pore throats. Complex clay minerals in these formations can create difficulties during drilling or workover operations. While the bottomhole assembly (BHA) is being replaced and flowback stopped, fresh water soaks into the formation for longer durations, resulting in longer contact with clay minerals. This can create a multitude of problems associated with clay swelling, including formation damage. This paper describes a clay stabilization additive that adheres to the clay surface and provides clay swelling and fines migration control, reduced friction, and decreased hydrostatic pressure when exposed to a freshwater-based fluid system. The product was evaluated in the laboratory using various core samples from Field A. During this evaluation, X-ray diffraction (XRD), X-ray fluorescence (XRF), linear swell meter (LSM), and capillary suction time (CST) assessments were performed. The clay stabilizer showed excellent results. This additive use can help to increase the efficiency of downhole motors and drill bits as a result of low friction pressure. This new stabilizer does not require special equipment, like other salts; consequently, it reduces time required for mixing while pumping. In addition, the blend is mixed at a lower concentration, which helps to solve logistical challenges, making it more efficient at a lower cost than salts. The clay stabilizer discussed provides permanent protection with no effect on original permeability. In addition, the low concentration of the clay stabilizer showed better performance in LSM and CST.