Research On Replace Steam Flooding Method To Steam Stimulation Of Super Heavy Oil Reservoir

The Jurassic Qigu formation ultra-heavy oil reservoir in the field 32 well block of Fengcheng oil field is located at the edge of northwestern Junggar basin.It owns three sets of oil layers: J₃q^2-1+ J₃q^2-2?J₃q^2-3?J₃q₃.At present,it has developed into the late period of huff and puff and it has an average throughput of 10.6 cycles?the straight well is 10.1 cycles;the horizontal well is 11.9 cycles?.Besides,the comprehensive water containing is rising year by year;The ratio of oil and gas and the production of single well are decreasing.So,it is urgent to change the development mode to stabilize production.Four kinds of replacing development processes in thermal production of heavy oil reservoir in the later period of the huff and puff have been formed on the base of describing the previous research result of fine reservoir accurately and introducing the idea of oil displacement-drainage effect.They are the vertical well steam drive with short well spacing,VHSD,cubical 30 m HHSD and 60 m HH.The vertical well steam drive with short well spacing technology is conducted through test-in-place in nine well groups,and the same with the VHSD technology in nine well groups,the 60 m HHSD technology and the HHSD technology in four well groups.According to the development regular of steam injection and puff of ultra-heavy oil,the time of the transforming development modes in the late steam huff and puff has been set up.Meanwhile,fine control technology of the oil displacement-drainage effect,whose cores are discharge injection production voidage technology,sub-cool control technology,equilibrium expansion of steam cavity technology,has also initially formed by the use of oil reservoir engineering tracking optimization technology.The following understandings are figured out by this programme research: 1.The replacement development process of thermal production in ultra-heavy oil reservoir in the later huff and puff period is formed on the basis of the oil displacement-drainage effect andthe previous study on optimization of reservoir engineering;2.According to the development regular of steam injection and puff of ultra-heavy oil,the time of the transforming development modes in the late steam huff and puff has been determined at the point when the inflection point appears in the injection ratio,liquid yield and reservoir water storage,usually is 8 cycles,and the recovery degree is 15% to 20%;The compound fine control technology,whose core is discharge injection production voidage technology,sub-cool control technology,equilibrium expansion of steam cavity technology,has also initially formed.The multi-layer comprehensive adjustment scheme of field Zhong 32 oil block is formed based on describing the reservoir accurately,understanding the development regular further and exploring the development tests,which offers some technological references for the similar reservoir's development and adjustment and has great application prospect and extensive popularization space.