The Mode Of Gas Channeling And Technology Of Anti-channeling For Multi-thermal Fluid Huff And Puff

The multi-thermal fluid is a component mixed with hot water,CO₂ and N₂.The main mechanisms to improve recovery are viscosity reduction by heating and dissolving of CO₂,as well as pressure maintenance and cleanup.As a new thermal technology,the multi-thermal fluid buff and puff has been applied successfully in heavy oil reservoir of Chinese Bohai Bay.It can increase oil production effectively,but gas channeling became more and more serious with the increase of cycle rounds.This not only seriously affected the energy efficiency of gas and heat,but also leaded to produce abnormally.Therefore,the research on the mode of gas channeling and technology of anti-channeling in multi-thermal fluid huff and puff is of great significance to implement the huff and puff extensively.With the geology and production datum of Bohai Bay oil field,the numerical simulation model of the multi-thermal fluid buff and puff is established.The precision of the model is validated by the history matching of daily oil production and water cut.The relationship of injection and production is analyzed on the basis of the oil field dynamic data.The relationship of adjacent well gas channeling well and corresponding injection well is confirmed.It indicates that gas channeling interval can characterize the velocity of gas channeling precisely as the history matching index of gas production.Based on the reservoir geology and production characteristics,the single-well conceptual model of the multi-thermal fluid buff and puff is used to research the relationship between fluid temperature and gas distribution.3 multi-thermal fluid modes are proposed by analyzing the characteristic of gas saturation distribution in multi-well model in different conditions.The modes proposed are applied to classify multi-thermal fluid buff and puff wells in the test block.The result shows that the modes proposed are proper and feasible.Combined with the influence factors of increasing gas channeling,the causes of different gas channeling modes are validated and the anti-channeling measures are proposed pointedly.For the characteristics of huff and puff wells and the improper injection technology,the technique of multi-well simultaneous injection and production for multi-thermal fluid is applied to prevent channeling.Based on the difference of the simulation oil production results about well numbers,injection combination and injection sequence,the optimal injection scheme recommended is two-well alternate injection with the combination and sequence of?B29H2/B42H???B36M/B44H???B34H/B33H?.In order to prevent gas channeling resulted from high permeability channels,the technique of thermo-sensitive gel with foam assisted for multi-thermal fluid buff and puff is proposed.The plugging experiments of foam and thermo-sensitive gel are used to validate the precision of characteristic parameters applied in the simulation model.Combined with the results of the history matching of characteristic parameters,the simulation model is applied to analyze influence factors and research the plugging mechanism,and the optimal injection scheme is recommended with 2.5%of foaming agent concentration,1.5%of temperature sensitive gel concentration of 1.5%and 150m³ of the volume of thermo-sensitive gel.