A new model selecting shale gas wells for foam deliquification based on geological and engineering conditions

Abstract As many factors affect the selection of shale gas wells for foam deliquification treatment and these factors are in complex relationships, it is hard to pick out shale gas wells properly. In this work, to solve this issue, a new well selection model considering the influences of multiple geological and engineering factors was proposed. Firstly, the geological parameters of 3D sweet spots were obtained by establishing a geological model of the study area. Secondly, the reservoir numerical simulation was employed to quantitatively evaluate the distribution of remaining gas and formation energy of candidate wells, and the key geological and engineering parameters affecting productivity were identified by the grey correlation analysis method. Finally, according to the distribution ranges of key geological and engineering parameters of candidate wells, a new concept of optimal ideal well was proposed, and the Euclidean distances between candidate wells and the optimal ideal well were worked out to quantitatively evaluate and rank stimulation potentials of the candidate wells. The research results have been applied to the shale gas reservoir of Longmaxi Formation in Sichuan Basin. The results suggest that the main factors affecting the productivity include the length of horizontal section, porosity, permeability, gas saturation, swept volume of fracture network, recovery percent of reserves and formation energy retention degree. The field application has confirmed that the productivities of horizontal wells treated by foam deliquification process have a good correlation with their Euclidean distances, with a correlation coefficient of 100%. The wells had a daily gas production increment of 19.6% on average. The research results have an important guidance on well selection and popularization of foam deliquification.