Abstract
Excessive production of water and aqueous fluids from oil and gas wells could pose problems such as reduced well productivity and increased operational costs. The relative permeability modifier (RPM) is an effective solution compared to other conventional water control methods to reduce associated processing and disposal costs, while also extending the productive life of the well. Instead of indiscriminately shutting off fluid flow into the wellbore, the RPM fluid is pumped into the formation and targets only the water phase of the produced fluids, and not the hydrocarbons. As a result, water production is selectively restricted while oil and gas production continues unimpeded.
Currently, most RPM technologies applied in the field are intended for sandstone formations. This paper illustrates a newly developed RPM specifically designed to address water control for carbonate reservoirs (RPM-T). The RPM developed in this work has been rigorously tested under varying temperature, concentration, and mineralogy conditions. Fluid compatibility, packed-bed and core-flow testing have been performed to develop this RPM-T for water conformance.
The ability of the potential RPM-T candidates to confine water flow was screened by carbonate sand-packed columns. Laboratory core flow testing was performed using carbonate core plugs to measure regain permeability from 200°F to 300°F. Laboratory results indicate RPM-T can reduce permeability to water by more than 85% while having minimal impact on the permeability to oil (oil permeability maintaining > 80%). RPM-T also showed excellent thermal stability by registering its effectiveness at 300°F and above. The novel RPM-T developed in this work was shown to work for both carbonate and sandstone formations. This implies a greater versatility in application and reduction in surface inventory for mixed-lithology fields.
The RPM-T improves well economics by significantly reducing costs due to water treatment, disposal, and conventional workovers, while increasing oil or gas production through enhanced drawdown and hydrocarbon inflow. It also enables reduced CO2 emissions due to smaller volumes of produced water for surface treatment, handling, and disposal.