GOALI: The Use of Sequestrants for the Dissolution of Scaling Deposits

North Carolina State University, Raleigh NC

Investigators

Abstract

Grant, Christine S. North Carolina State U "GOALI: The Use of Sequestrants for the Dissolution of Scaling Deposits" The primary goal of this research is to elucidate the transport and interfacial mechanisms responsible for the dissolution of mineral salts in the presence of environmentally benign chelating polymer(s). In this study, barite is selected as the major working material due to its prevalence in scale deposits found in petroleum processing pipes and associated equipment. The PI has established that at a specific pH, there are multiple polymer species present in solution. The behavior of these individual species and their cooperative influence on the rate of dissolution is crucial to understanding the dissolution process. Dissolution studies will be conducted in different pH regimes corresponding to a study of the various dominating polymer ligand species in solution. The GOALI component of this proposal will occur with Dr. Ian Collins, a Scale Management Consultant in the Well Performance Team of the Upstream Technology Group at British Petroleum in the UK. There are three aspects of the new BP interaction: (i) BP researchers will provide technical information and "research grade" and "field grade" barite samples for controlled hydrodynamic rotating disk studies; (ii) specific conditions for dissolution experiments will be developed in conjunction with BP researchers and actual field engineers to insure relevance to current and future petroleum exploration activities; (iii) the BP research staff will serve in an advisory role to the student researchers on the projects. The PI will also continue to utilize the expertise of the chemists at Donlar Corporation in the chemical reaction kinetics sequences for the process. Broader Impacts: Preliminary batch testing of barium sulfate in the presence of thermal polyaspartates, indicate there is an inhibition of dissolution at specific conditions. In the proposed research, The PI expects to see enhanced dissolution of the barite, a common species in petroleum processing scale at specific conditions of pH, shear, polymer concentration/type. This will correspond to a specific combination of polymer conformation/adsorption resulting in unique dissolution mechanism. There should be variations in the behavior on pure minerals and for mineral composites that represent actual industrial conditions. In contrast to studies that seek to inhibit the formation of mineral scales on piping and equipment, the PI's approach focuses on the dissolution of the resulting scale. In this regard, the strategy is comprehensive in its study of the chemistry of interaction, the interfacial phenomena and the transport mechanisms (e.g., mass transfer, fluid flow) during the dissolution process; it also utilizes industrially relevant configurations and chemistries to perform the testing. This research could result in alternative environmentally benign sequestering agents for the dissolution of mineral deposits. Specifically, the prevalence of barite in scale deposits found in petroleum processing pipes and associated equipment is a significant problem area; a green chemistry solution that could benefit the economics of the process and the environment.