chapter
Wells partially cemented with cavities
Pages 43

Figure 6. Wells partially cemented with cavities-diagrams with geomechanical problems, consequences, risks and minimization measures.

Causes for geomechanical

problems Risks Minimization measures

− Additive mixture in the cement

− Construction of a reinforcement ring beyond the walls of the well

− Hydrofracturing to improve the permeability during water pumping and primary production of methane − Deterioration of cement or not existing − Chemical dissolution of the cement − Reduction of neutral pressures during water pumping and primary production of methane

− Hydrofractures by the overlying strata − Volume diminishing due to methane adsorption − Displacements in the reservoir and in the surrounding rock mass − Settlements at surface − Sliding movements of faults and discontinuities pre-existing in the coal − Leakage through faults and discontinuities pre-existing in the coal

Figure 7. Wells partially cemented with cavities-diagrams with geomechanical problems, consequences, risks and minimization measures.