... porosity drilling permeability fracture cracks Coalbed methane (CBM) gas reservoirs have gained significant attention during the last 20 years because the CBM reserves accounts for about 17% of the total recoverable natural gas reservoirs in the United States alone ( 1 2 ). CBM gas reservoirs...

... compressive stress caused by overloading that results in the crushing of the rod, and high stress concentrations present at the grooves of the endfitting that initiate premature cracks. Based on the result of this study, enhanced design of the composite sucker rod system can be accomplished. Contributed...

... and their analysis becomes a problem. The paper presents mathematical models of the pressure-volume behavior for two different possible failures around the casing shoe, annular crack (cement-rock parting) and formation fracture. The study submits that these two failure modes would control abnormal LOT patterns...

.... This may be due to a region of circumferential partings and small cracks that lead to high porosity or due to the possible artifacts discussed in the paper. Qualitative results have also been obtained for a tight sandstone for which underbalance was insufficient to remove debris from the perforation tunnel...