Inference of rock pressure-production properties from gas-oil production logs

In a synthetic multilayer reservoir model with a gas cap, PL interpretation recommends a critical bottom-hole pressure to prevent high gas production because of (i) downward advancement of the gas displacement front, and (ii) released gas from oil solution. The estimation error is less than 20% for near-borehole gas saturation, and less than 25% for near-borehole permeability. However, the reliability of estimations is adversely influenced by conditions of immovable gas saturation in rock formations. Additionally, we examine a field example consisting of a gas-oil sand-shale laminated system where PL interpretation is carried out to quantitatively the investigate inflow performance relationship of individual flowing units. The interpretation method integrates well-log-derived and PL-derived permeabilities to quantify the depth distributions of near-borehole skin factor and gas saturation. The estimated near-borehole reservoir model subsequently quantifies more than 60% reduction of unwanted gas production caused by a gas shut-off remedial operation.