The Study On Water Invasion Rules And Numerical Simulation Of Deepwater Gas Reservoir

Exploration and development of deep-water oil and gas fields is an important strategy for China's energy development towards the ocean.The South China Sea is rich in oil and gas resources,but 70% of its reserves are in the deep ocean,making exploration extremely difficult.In N-1,the geological reserves controlled by side and bottom water accounted for 86.49% of the total reserves.The risk of water invasion from side and bottom water is high,and the proportion of medium and high water risk wells is large.Some wells are closer to the water.Bottom water coning is possible.Due to insufficient understanding of water invasion characteristics,unclear understanding of bottom water development characteristics and water invasion rules,it is urgent to establish a South China Sea deep-water gas field development model,clarify the water invasion rules of deep-water edge and bottom-water gas fields,develop deep-water well water control technology,and reduce edge Bottom water coning speed to extend the water-free gas recovery period.This paper studies the water invasion mechanism and water invasion law of deep water gas reservoirs and numerical simulation of water intrusion under different water control processes.The water control effects of different water control processes are evaluated.A single well in N-1 gas field was evaluated.It optimized the production system and forecasted the development effect.The main results and understandings achieved are as follows:(1)The main feature of gas-water two-phase percolation in deep-water gas reservoirs is by-pass flow.The main form of water invasion is formation channel water channeling along high-permeability channels.By-pass and high-permeability zone water channeling also forms closed gas in the reservoir.The main reason for the reduction of the ultimate recovery of gas reservoirs.The water invasion mode of the heterogeneous bottom water gas reservoir is a discontinuous vertical channeling-transgressive composite water invasion,while the water invasion mode of the non-homogeneous edge water gas reservoir is a discontinuous horizontal channeling-vertical channeling composite water invasion.(2)By analyzing the water invasion law of gas reservoirs through reservoir engineering methods,it is known that the amount of water intrusion and the extent of migration of edge and bottom water increase with the increase of reservoir permeability,gas production rate,and water body size.The final recovery of gas reservoirs decreases with the increase of reservoir permeability,gas recovery rate,water body size,and formation pressure.(3)By comparing and analyzing the development effects of different water control technologies,it is found that the variable density sieve can control water more effectively than the central water control technology,the bypass water control technology and the super-hydrophobic material water control technology.Advancement of bottom water to achieve water invasion control in gas reservoirs.(4)Research on the development strategy for N-1-L block,we found that the variable density screen tube-coated sand composite water control technology,combined with the intermittent gas production development system,can improve the recovery factor by 10.31%,The ultimate recovery of the gas reservoir is as high as 70.34%.