Abstract: Methods for inducing the precipitation of substantially water insoluble mineral carbonates in pores, spaces and fractures by conveying a carbon-dioxide (ie. CO2) bearing gaseous phase or an oxidised-carbon-bearing aqueous phase into spaces where reaction with an existing or introduced fluid phase of appropriate composition occurs, or by conveying a fluid of appropriate composition into spaces where reaction of the fluid components with a fluid delivery medium occurs, or by conveying a fluid of appropriate composition into spaces under controlled physical conditions such that unassisted reaction of the fluid components occurs.