Study on Thermal Productivity Multiplier of Slant Well and Vertical Well in Offshore Oilfield Thermal Recovery Development

The productivity evaluation of thermal recovery wells in offshore oilfields of China mainly relies on well test method or analogy method. Due to the absence of long time thermal production data and the general use of wellbore heat tracing test method, productivity evaluation using well test method requires evaluation of thermal recovery capacity multiplier characteristics with reference to similar oil fields. However, thermal productivity multiplier is influenced by reservoir properties, heat injection capacity and well types. At present, there are few studies on thermal productivity multiplier, while they are usually obtained through dynamic analysis of actual production wells. In this paper, a composite flow model of heated and unheated zone is established, and a formula for calculating thermal productivity multiplier of directional wells relative to vertical wells is established. Then a series of plates of thermal productivity multiplier are plotted for different heating radius, well spacing and well inclination. Combined with numerical simulations, the plate of analytical model is then validated with numerical simulations, which benefits the evaluation of offshore oilfield thermal recovery development for different well types.