Analysis on influencing factors of horizontal well productivity in tight sandstone reservoir – Taking Q gas field in the middle of Ordos Basin as an example

Abstract

Horizontal well development technology has become the main development means of Upper Paleozoic tight sandstone gas reservoir in Ordos Basin. The study area is a typical tight sandstone reservoir, and horizontal wells have gradually become an important driving force for the effective development of the gas field. In order to clarify the main controlling factors of horizontal well productivity in this area, the influence on horizontal well productivity is expounded from two aspects: different types of sedimentary microfacies and different spatial development modes of sand bodies. The production capacity of horizontal wells is analyzed and evaluated by using lithology photos, logging data, nuclear magnetic resonance data, gas test data, production performance curve and other dynamic and static data. The results show that: ① during the sedimentary period of tight sandstone reservoir in the gas field, the hydrodynamic force plays an important role in controlling the productivity of horizontal wells; ② The spatial development model of sand body has a decisive impact on the productivity and stable production capacity of horizontal wells. The trajectory types of horizontal wells corresponding to the spatial development model of gas field sand body are flat, highly deviated and stepped; The three types of horizontal wells have a certain stable production capacity (> 2000 d). Among them, flat and high angle horizontal wells show good stable production 765capacity, and the stable production capacity of stepped horizontal wells is limited, but it is still a necessary supplement for the benefit development of the block; ③ According to the influencing factors of horizontal well productivity, the phased production and stable production capacity of the block can be predicted, which provides a basis for block planning. This method is also applicable to the production prediction of other similar gas reservoirs.