Abstract
Gels are used worldwide to control water production in oil and gas wells in order to improve hydrocarbons recovery, to increase sweep efficiency during water injection by plugging high permeability layers, or to keep wells producing by reducing water production rate. The critical issue is the correct identification
of water production mechanism. After this step it is important to consider whether the more reliable mechanical systems can be applied before focusing on chemical systems.
For the chemical system approach there are two more critical points to consider:
- the selection of the chemical system;
- the correct placement of the treatment fluid.
The maximum benefit that can be achieved depends on the knowledge of the status of the field and/or the well and on a good problem diagnosis.
For chemical Water Shut Off (WSO), the support of laboratory activity is very important to select or verify the right system and formulation in order to increase the rate of success of the treatment itself.
A review of water problems and gel placement techniques has led to a study of alternative and unusual displacement methods using gels and polymers. These techniques have been applied in order to complete the hydrocarbons recovery in shaly gas depleted reservoirs.
A new bullheading technique had been developed to reduce costs and to make WSO more attractive. Moreover, Relative Permeability Modifier (RPM) applications had been designed to treat more difficult completions (dual completion, short strings, selective strings, gravel pack completions) and thin multi-layered reservoirs.
In this paper a brief summary of laboratory activities for a correct polymers and gels selection is reported as well as field treatment data and results from bullheading gel treatment and from RPMP application.
These applications had been studied to reduce treatment costs by rigless operations, produce marginal reserves from depleted and multi-layered reservoirs.
Many of the issues deal with gas wells applications, but they can be easily applied to oil wells.