A Breakthrough Water Shutoff System for Super-K Zones in Carbonate Ghawwar Field: Adsorption and Polymer System

摘要

The overall objective of the project is to develop a water shutoff chemical (Sealant), which can be used by Saudi Aramco to control excess water production in carbonate formations. Excessive water production from hydrocarbon-producing wells can adversely affect the economic life of the well. It was estimated that an average 2.8 barrels of water is produced for each barrel of oil worldwide. A new water shutoff polymer system was developed for carbonate formations. The developed system can bond to carbonate and shows great stability. The major challenge of water control in carbonate reservoirs are polymer bonding to the rock surface. Most of the commercial products are designed for sandstone formations. Most polymers will not strongly adsorb to carbonate reservoirs particularly under high fluid flow or high salinity. The polymer system developed is designed to overcome this and chemically bond the polymers to the surface of the carbonate. A well-defined polymer system with the ability to chemically bond to carbonate surfaces were also realized which represents the first example of an adsorption system for carbonate reservoirs and could have broad reaching applications. This represents a significant breakthrough as this can overcome one of the key obstacles of water control in carbonate formations. This paper demonstrates the laboratory work carried out to develop and investigate the efficiency of Smart Sealant, compared with Organically cross linked polymer (OCP), in both Supper- K and fractured rocks. Core flow testes indicate significant drop in water production for both fractured and Supper-K formation. When chemical treatments were applied, the polymer system was able to withstand the differential pressures and did not allow the flow of water in both high permeability cores and fractures. Coreflood results indicate that OCP was unstable with carbonate core sample and leached out after 4 pore volume of brine injection. ESEM and EDS analysis confirmed that the Smart Sealant treatment of the core plug resulted in some of the used polymer product blocking fractures and pores. This finding confirms adsorption and stability of Smart Sealant polymer on the rock surface, blocking fractures and reducing permeability of fractured core samples.