Methods for Improving Precision of Production Prediction in Low Permeability Oil&Gas Fields

The reserve-production ratio control production prediction method has the characteristics of less data and parameters required, higher prediction accuracy, and is one of the most commonly used methods for production prediction in oil and gas strategy research. In recent years, with the change of oilfield development objects from mid-high permeability and conventional reservoir types to ultra-low permeability, complex lithology and unconventional reservoir types, the proportion of reserves and production of low permeability reservoirs is increasing. At present, the developed reserves of low-permeability reservoirs in China account for nearly 40% and the annual production accounts for nearly 30%. Due to poor physical properties and fracture development of low-permeability reservoirs, the development effect is not ideal. There is a great difference between the recovery factor calibrated at the initial stage of development and the dynamic recovery factor after development, which has a great impact on the reserve-production ratio control prediction method with recoverable reserves as an important parameter. Therefore, through the analysis of the principle of the reserve-production ratio control prediction method, the key parameters affecting the prediction accuracy are identified. Considering the complex situations of incomplete development history data, the production has not entered the decline stage, as well as the reserve production balance coefficient is greater than 1, the recalculation method of cumulative recoverable reserves and correction method of annual recoverable reserves are studied. An example calculation shows that the new method can significantly improve the production prediction accuracy.