Study On Dynamic Reserves And Water Influx Channel Of K Gas Field

According to the size of the pressure coefficient,oil and gas reservoirs are generally divided into three types:abnormally high pressure,normal pressure,and abnormally low pressure.According to China’s gas reservoir classification standards,abnormally high-pressure gas reservoirs refer to gas reservoirs with a pressure coefficient greater than 1.3.The K gas reservoir in the study block belongs to abnormally high-pressure gas reservoirs.Abnormally high-pressure gas reservoirs have a variety of driving mechanisms and belong to the mixed driving type.In addition to the gas expansion force of the atmospheric pressure gas reservoir and the expansion forces of the edge water and bottom water,the abnormally high-pressure gas reservoir also has its specific driving mechanism,such as Rock squeezing or crushing,rock and water expansion,shale water intrusion,water intrusion at the edge of aquifer,etc.Therefore,there are many factors affecting the calculation of dynamic reserves of K gas field and the types of water intrusion are complex.It is impossible to use traditional methods to calculate and judge.This paper studies the dynamic reserves of K gas field and the channel of water intrusion.According to the abnormal high-pressure characteristics and development status of the K gas field,the pressure drop method,trial and error method,pressure recovery well test method,elasticity two ideas,Blasingame method,material balance method,water drive law curve method are used to calculate the dynamic reserves of the K gas field,and The calculated dynamic reserves and the static reserves obtained by the static method are used for error calculation,and the pressure drop method is improved to improve the accuracy.Based on the principle of material balance,considering the stress sensitivity and water intrusion of fluid,bedrock,and cracks,a material balance equation is established,and the calculated dynamic reserves are more accurate.In order to better identify the dominant channel,the internal driving energy,water intrusion,and water body of the K gas field were evaluated,and the sensitivity factors of dynamic reserve calculation were analyzed using radar charts,which paved the way for identifying the dominant channel for seepage.The mine data method,physical experiment method,and numerical simulation analysis method are used to determine the permeability difference limit of the water invasion dominant channel,and the dynamic feature method,output profile analysis method,static data analysis method,gas reservoir structure analysis method are used to identify the K gas field production wells.Whether there is a dominant channel for water intrusion,and finally a conceptual model is established for numerical simulation to determine the type of water invasion in these wells with superior channel for water invasion.The research shows that:the dynamic reserves calculated by the pressure drop method are 256 billion cubic meters with a relative error of 0.21.The improved pressure drop method is 212.17 billion cubic meters with a relative error of 0.0006;the dynamic reserves calculated by the trial and error method are 250.99 billion cubic meters,relative Error 0.18;Dynamic reserves calculated by Blasingame method is 226.04 billion cubic meters,relative error 0.06;Dynamic reserves calculated by traditional material balance method is 231.63 billion cubic meters,relative error 0.09;Dynamic reserves calculated by water drive law curve method583.32 billion cubic meters,with a relative error of 1.75.Considering the stress sensitivity of fluids,bedrock and fractures,the dynamic reserves calculated by the water intrusion mass balance equation are 220.654 billion cubic meters,with a relative error of 0.03,which is more accurate than the traditional mass balance method.From a practical point of view,the annual gas production has the greatest impact on the calculation accuracy of dynamic reserves;the natural gas elastic expansion driving index of the K gas field is below 0.5,and the water flooding index is within the range of 0.1～0.3,which belongs to the medium elastic water flooding gas reservoir;The pressure values are all greater than 0.5,indicating that the K gas field belongs to an active gas reservoir with side and bottom water,and the annual water intrusion is 1040.46×10~4m~3.The water body multiple is 4.8315,the water body volume is Vpw is 37.71×10~8m~3.According to the dynamic feature method,6 wells with predominant seepage channels are identified:K203 well,K204 well,K2-10 well,K2-12 well,K2-Wells 13 and K2-14,of which wells K203,K204,K2-13,and K2-14 belong to the type of fault vertical channeling and transgression,and wells K2-10 and K2-12 belong to the high-permeability strip along the bottom and bottom water.With intrusive type;the remaining 12 wells are judged to be risk wells based on the permeability difference limit and dynamic characteristics above:Wells K2-8 and K2-11,pay attention to prevention.