Research On The Characteristics Of Bubble Flooding And Anti-gas Channeling Technology

Wenxi block X belongs to high temperature（84.2℃～90℃）,medium salt（salinity 10967～15283mg/L）,low permeability(average permeability is 49×10^-3 m²)thin oil（crude oil viscosity 0.7mpa·s～3.2mpa·s）reservoirs.Since the implementation of foam flooding in this block in January 2015,the water content of the main production Wells in the foam test area has been reduced by a small margin（from 98%to 90%）and daily oil production has been rising rapidly（from 2t to 8t）,with obvious effect of increasing oil and precipitation.However,since January 2016,the production Wells in the test area began to see intermittent gas,and the gas-oil ratio of each well group rose rapidly.In the following five months,the daily gas output in the test area reached 12,142m²（ground level）,and the nitrogen content was up to 67.8%.The foam flooding effect began to gradually decrease.Up to now,all the 10 production Wells in the test area have gas channelling,with a cumulative increase of more than5,000 tons of oil.Although certain effects have been achieved,there is still a big gap with the expectation.The characteristics of foam flooding in wenxi X can be summarized as follows:foam flooding takes effect before gas is seen,and then gas is seen quickly after gas is seen,and the timeliness of foam flooding is short.In order to solve the problem of rapid gas detection and even gas channeling in producing Wells after foam flooding,the bubble flooding measures resulted in low recovery.In this paper,the characteristics of bubble flooding and anti-gas channeling technology are studied.First of all,through the dynamic characteristics of the mine gas（producing gas-oil ratio）and the oil well output components,the analysis of experimental zone producer gas characteristics,and the optimization of foam system,add sealing channeling system and layered points on anti channeling thoughts research is suitable for this kind of high temperature,severe heterogeneity,low viscosity of crude oil and for low permeability reservoirs of anti-gas channeling foam flooding technology.Wen Xi X block formation fluid properties,the author of this paper,by using the Waring Blender anti-gas channeling a variety of foaming agent has been screened in the early and foam system performance evaluation,get high reservoir temperature foaming capability,high oil,salt resistance and low dynamic adsorptive retention rate of KX-37-FC system,foam system and under the condition of the reservoir,the use of single tube displacement experiment contrast evaluated the effective concentration,gas liquid ratio,injection pattern,injection rate and injection slug gas channeling in the influence factors of foam system such as nitrogen seal,the influence law of retention capacity.Then the gas detection law and oil displacement effect of foam flooding under different permeability level difference and main oil layer height difference were studied by using dual parallel sand filled pipe cores.The results of single tube show that the KX-37-FC system has ideal anti-gas channelling performance under the conditions of effective concentration 0.10%,gas-liquid ratio1.0:1.0,foam generator injection,injection speed of 1m/d and injection slug of 0.3PV.Parallel displacement and the experimental results show that:only gas channeling control from the viewpoint of optimization foam system,the technology has a certain technical limit,permeability differential for 1～14.6 or reservoir height difference is less than 80 m,stable optimization system can control gas,permeability differential of14.6～38.4 or reservoir height difference of 80～300 m,the overall performance of flat type gas breakthrough characteristics,and permeability differential is greater than38.4 or reservoir height difference is more than 300 m,as a whole is to speed up the type of gas breakthrough characteristics,but in general,the optimization system of controlling gas performance is far superior to mine use system of XHY-4.On the basis of laboratory experiments,combining with the permeability level difference and reservoir height difference of each production well group,the bubble flooding and gas-channeling prevention plan of the well group was designed,and CMG numerical simulation software was used to simulate and predict the gas-channeling control and oil-displacement effect of gas-channeling prevention technology of each well group.The results showed that:（1）experimental zone WX1-63 well group permeability differential of 11.2,the main reservoir height difference of 67 m,see gas characteristics of overall performance is slow running model,only use KX-37-FC foam gas channeling control scheme,can achieve the ideal effect of stabilizing oil gas control,measures after 90 d,producing gas-oil ratio to reduce the percentage of 73.6%,（2）the WX1-64 well group permeability differential of 32.1,the main reservoir height difference of 217 m,overall performance for speed up the gas phase.Need to use KX-37-FC foam+0.6%microspheres sealing channeling system gas channeling control scheme,in order to achieve the ideal effect of stabilizing oil gas control,measures after 90 d,producing gas-oil ratio to reduce the percentage is 86.2%,（3）the WX1-74 well group permeability differential of 74.3,the main reservoir height difference of 315 m,overall performance for quick darting type serious gas phase,need to be used on the basis of separate hierarchical KX-37-FC foam gas channeling control scheme,in order to achieve the ideal effect of stabilizing oil gas control,measures after 90 d,producing gas-oil ratio lower percentage of 93.9%.Finally,after the corresponding anti-gas channelling measures were applied in each well group,the foam flooding in the test area was predicted to increase the recovery rate by 12.98%OOIP compared with water flooding,with an accumulative oil increase of 15.71×10⁴t.