Research On Steam Flooding Technology For Medium-shallow Heavy Oil Reservoirs

Heavy oil as unconventional energy accounts for a sizeable proportion of the world's oil and gas resources,the high productivity of heavy oil has become an important way to ease the energy crisis,especially in the growing energy shortage situation.China is rich in heavy oil resources,but it is difficult to exploit due to the density,viscosity and flow hard.As for the history of heavy oil exploitation of Xinjiang Oil field,steam-injection is the major method to exploit at present.After several-rounds of steam-stimulation for the heavy oil reservoir,the effect of exploitation become worse significantly,in order to increase the production of crude oil further,as the promotion and usage of steam-drive replaced the steam-stimulation is imminent.With the two kinds of steam-injection of thermal recovery technology,steam-stimulatio'n's recovery is about 20%generally,while the technology of steam-drive makes oil recovery increased by 30%,or even more.So it is an effective and economical way of thermal recovery that be favourabled by the field engineers.In this paper,take the middle-shallow heavy oil reservoir block of Xinjiang Oil field as an example,mainly carried out the following tasks:(1)Researched the heat loss rule of steam-injection wellbore in the steam-drive process,compiled the procedures of the wellbore overall heat transfer coefficient and calculate it,and analyzed the sensitivity of steam-injection pressure,steam-injection rate and steam-injection temperature within the wellbore,(2)Established a vertical well steam-drive model and vertical-horizontal well steam-drive model by the blocks geological data and fluid data,analyzed the effect of production of two models that the change of parameters,and optimized the injection-production parameters of the two models through Orthogonal Design Method.(3)With the vertical-well model established,calculated reservoir parameters(reservoir effective thickness,reservoir net total thickness ratio,porosity,oil saturation)on the effects of steam-drive,and analyzed the important role of physical properties of crude oil,different layers of steam-injection,transfer-injection timing and the clearance of steam injection on effeect of steam-drive.(4)Calculated the cumulative production of five-spot pattern,reverse seven-spot pattern,reverse nine-spot pattern,line-drive pattern of the heavy oil blocks respectively at the economic limit of OSR which equals 0.15 and 0.10,compare effect of different well pattern,do the economic evaluation of each pattern and give some advices.These have an important guiding role at steam-drive of middle-shallow heavy oil reservoir's exploitation similar.