Research On The Well Test And Production For Multiple-fractured Horizontal Well In Tight Gas Reservoirs

Tight gas reservoir is a kind of important unconventional energy,the reservoir volume of which in China is pretty abundant,widely distributed in the Tarim Basin,Ordos Basin,Qaidam Basin,Quasi algor Basin and other regions.Due to the poor permeability and connectivity,most developments of tight gas take multistage fracturing horizontal well technology to achieve the purpose of production.Multistage fracturing horizontal well can remove the pollution near the wellbore,connecte the gas reservoir area and expand the drainage area by fracturing multiple cracks.Well test and productivity analysis are the significant methods to study the reservoirs,and can provide effective guidance for development.This paper analyzed the seepage theory of tight gas and multistage fracturing horizontal well,established and solved the multistage fracturing horizontal well test model with infinite boundary,rectangular closed boundary and rectangular constant pressure boundary,studied the characters of well test template curves and the sensibility of various parameters.Contrasted 8 commonly used horizontal well production computational formulas,it was found that Borisov formula,Joshi formula,Lang zhaoxin formula and Chen Yuanqian formula can be used to calculate the productivity of tight gas horizontal wells,but these formulas didn’t take into account the impact of fracturing on horizontal well productivity.This paper also deduced the productivity model of infinite formation and boundary formation,and the factors such as stress sensitivity,gas slip effect and epidermal pollution were considered in the model.The accuracy of the formulas was verified by sample calculation,and the affections of fracture parameters and formation parameters to horizontal well productivity were analyzed.The models proposed in this paper can be applied to practice and has some guiding significance.