Optimization of Downhole Throttling in High-Pressure Gas Wells Based on OLGA Simulation

Downhole throttling technology is an efficient means of hydrate prevention and control. How to establish an effective throttling pressure difference in a reasonable time to ensure that the wellhead pressure and temperature are quickly reduced to a safe range has become the key to the successful implementation of downhole throttling technology. To address this issue， the OLGA transient multiphase flow simulator was used to conduct dynamic simulation on the pressure， temperature and production during flowing of gas wells. Then， the flow and heat transfer characteristics in the wellbore under different choke diameters and flowing production conditions were analyzed， and the risk of hydrate formation was predicted. The research results show that the choke diameter significantly affects the time required for the wellhead pressure to decline to the delivery pressure and the stable production rate. Smaller choke diameter （e.g. 4.3 mm） increases the downhole flow resistance， accelerates the decline of wellhead pressure， but limits the stable production rate. Larger choke diameters （e.g. 5.4 mm and 6.0 mm） prolong the pressure decline time， but can achieve higher stable production rates in long-term production. Under the conditions of downhole throttle valve with small choke diameter and high flowing production rate， the post-valve temperature recovers fast， and the risk of freezing blockage is low. However， under the conditions of downhole throttle valve with large choke diameter and low flowing production rate， the post-valve temperature remains below the hydrate formation temperature for a long time， and the risk of freezing blockage increases significantly. In actual production， it is recommended to comprehensively consider surface processing capacity， gas reservoir development requirements and safe production demands to formulate the optimal downhole throttling scheme. The research results provide a scientific basis for the design and optimization of downhole throttling technology in high-pressure gas wells.