Regularity of permeability loss in gravel-packing layer for sand control during initial production

Wells with gravel packing for sand control may experience dramatic productivity decline shortly after production. Tests are conducted to highlight changes in permeability of compacted gravel-packing layers and plugging of such layers due to absorption. Eventually, patterns of permeability loss in gravel-packing layers during initial production are determined. Test results show, downhole compaction and crude oil absorption and plugging are main contributors for permeability loss in gravel-packing layer during initial production. Permeability of gravel-packing layer may decrease significantly with increase in external pressure. Permeability of gravel-packing layers compacted under pressure 40 MPa may be approximately 5%~11% of original permeability; Water permeability of gravel-packing layer may decrease rapidly after alternative displacement with permeability loss factor of approximately 0.75~0.85. Ratio of permeability loss in short duration may vary slightly with changes in displacement time and temperature. Based on relevant test results, prediction model and technique for prediction of permeability loss in gravel-packing layer during initial production have been constructed. The innovative model and technique may provide valuable guidance for research and production in relevant fields.