The Critical Pressure Difference Prediction of Sand Production in Deepwater Sandstone Gas Reservoirs

Sand production in deepwater gas fields can cause great harm, so it is vital to determine a reasonable production system. At present the prediction models of critical pressure difference of sand production in oil-gas wells are numerous, but among them there is no prediction model that aims at deepwater gas fields that the mining environment of high risks. The authors carried out a lot of experiments with real rock cores to simulate sand production in gas wells by using a set of self-developed radial displacement experimental devices. During experimenting they measured critical flow rates and critical pressure differences when sand production happened, and calculated the critical pressure differences of sand production under the condition of actual reservoirs. Comparing the results of the experiments with that of multiple sanding prediction models, the most suitable model for gas reservoirs was determined. Through doing error analysis and coefficient modification on the model, a simple and effective method was ultimately formed to predict the critical production pressure difference of gas wells. The research results showed that for gas fields if the production pressure difference was controlled within 0.4 times of the uniaxial compressive strength, sand production could be effectively prevented, and the prediction error could be controlled within 10%. This technique has been successfully applied in one deepwater gas field in the South China Sea areas, which guided the selection of sand control method and the design of production pressure difference, thereby ensuring reasonable and efficient mining of this gas field.