Coreflooding and Steady-State Principles Determine Reaction Kinetics

Abstract

This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper SPE 209380, “Reaction Kinetics Determined From Coreflooding and Steady-State Principles for Stevns Klint and Kansas Chalk Injected With MgCl2 Brine at Reservoir Temperature,” by Pål Østebø Andersen, Reidar Inge Korsnes, and Andre Tvedt Olsen, University of Stavanger, et al. The paper has not been peer reviewed. A methodology is presented for determining reaction kinetics from coreflooding. A core is flooded with reactive brine at different compositions with injection rates varied systematically. Each combination is performed until steady state, when effluent concentrations no longer change significantly with time. The authors also propose shut-in tests where brine reacts statically with the core for a defined period and then is flushed out. The residence time and produced brine composition is compared with the flooding experiments. This design allows characterization of the reaction kinetics from a single core. The steady-state method allows computationally efficient matching even with complex reaction kinetics. Introduction The complete paper presents a methodology to interpret reactive flow experiments. The main principle is to focus on the steady-state data collected when effluent concentrations do not change further with time for given injected composition, injection rate, core properties, temperature, and pressure. Such measurements depend only on the dynamic equilibrium between reactions, advection, and to some extent dispersion, while transient events and mechanisms can be ignored. The authors hypothesize that, by measuring such data under different injected compositions, injected rates, and temperatures, characterization of reaction kinetics is possible with great detail. This is demonstrated by performance of reactive flow experiments on chalk cores at varied conditions with the purpose of collecting steady-state data. A key advantage from the interpretation perspective is that complicated reactive transport equations can be simplified by ignoring the changes in time and only simulating and matching the steady state. The experimental setup is detailed in the complete paper, as is a general description of advection-dispersion-reaction systems, a description of steady states in an advection-dispersion-reaction system and an advection-reaction system, and a theoretical description of a magnesium chloride (MgCl2)/calcite system.