Research and Application of Quantitative Liquid-Loading Technologies for Gas Wells in Volcanic Reservoirs

摘要

The bottom water of volcanic gas reservoir in Daqing Oilfield is active,resulting in water production in nearly all gas wells.If dewatering measures can't be implemented in time,there will be more risks of liquid-loading in the wells.At present,there is no effective method of liquid-loading prediction for the wells,and the accuracy of the conventional single-methods of liquid-loading diagnosis is only 53.9%-76.9%.In order to guide the precise implementation of drainage measures,technologies of quantitative diagnosis and prediction of liquid-loading technologies were developed.In respect of the diagnosis,through optimizing weight coefficients,a multi-method combined diagnosis model based on optimal weight was proposed,which realizes the complementarity of different methods.A transient gas-liquid flow model coupled with wellbore and formation was established to realize quantitative prediction of liquid-loading.The technologies were applied in 274 wells in Daqing Oilfield.The result shows that 33.6% of wells are liquid loaded.According to the actual pressure gradient testing data,the average accuracy of this diagnosis method is 92.3%,15.4%-38.4% higher than that of the conventional single-methods,and the prediction technology helps effectively to predict the risk of liquid-loading 7 months in advance,which achieves the expected quantitative calculation accuracy and conforms to the geological characteristics of volcanic gas reservoirs in Daqing Oilfield.The technologies provide technical support for the effective implementation of drainage and production measures of volcanic gas reservoirs,and also a reference for water control and development of similar volcanic gas reservoirs.