大庆C区扶余油层二氧化碳驱控气窜技术研究及其效果分析
发布时间：2019-01-30 20:03
【摘要】：伴随注CO_2开发的推进,大庆C区近年来暴露出了气窜的问题,CO_2无效循环严重,产油量下降。因此急需合理有效的控气窜技术来辅助CO_2驱试验区的开发。本文根据研究区目的层的地质条件,分析了气窜的原因和难点,针对性的研制了封窜剂,并开展了封窜矿场试验。大庆C区,构造位于松辽盆地,以河流-三角洲相为主的沉积,扶余油层成岩作用强,岩性相对致密,分选系数平均为3.7,粒度中值0.07-0.14mm,以泥质胶结为主。区块内扶余油层50%的岩心渗透率都小于0.1×10-3μm~2,渗透率分布分散,其各向异性比较严重,导致地层条件下流度很高的超临界CO_2很容易发生指进,无效循环严重。尤其当渗透率小于1×10-3μm~2时,岩心水敏程度为中等偏强,前期的注水开发加剧了这一现象。结合目的层的这些地质条件,确定了适合这种特低渗透气驱油藏的封窜体系为泡沫类封窜体系。泡沫体系粘度低,其较低的表界面张力能够实现其有效注入,并在地层内发泡发挥堵气不堵油的作用;同时在起到稳泡作用的弱凝胶的选择上,也针对区块低孔低渗的特点优选了低分子量产品,体系基液粘度仅为8-12 mPa·s。该区块属于高地温梯度油藏,油藏温度大于80℃,需要选择耐温性高的泡沫剂和凝胶,针对C区扶余油层这种情况也做出了相应的优选和调整,实现了成胶时间3-7天可控;发泡体积550mL;泡沫半衰期60天以上。同时考虑到平均单井日产油0.3t的低产能,在工艺上取消了成本过高的气液混注工艺,调整为由泡沫、凝胶泡沫、防冻防腐段塞构成的段塞式封窜工艺,成本较气液混注工艺节约了一半。现场试验2口井,施工成本降低了一半。措施后注入压力上升了4MPa;注入剖面得到明显改善,原不吸气层位得到有效动用;连通油井日产油上升明显,取得较好效果。
[Abstract]:Along with the development of CO_2 injection, the gas channeling problem has been exposed in Daqing C area in recent years. The ineffective cycle of CO_2 is serious and the oil production is decreasing. Therefore, reasonable and effective gas channeling control technology is urgently needed to assist the development of CO_2 flooding test area. According to the geological conditions of the target bed in the study area, the causes and difficulties of gas channeling are analyzed, the channeling sealing agent is developed, and the field test of channeling sealing is carried out. In Daqing C area, the structure is located in Songliao basin, with fluvial and delta facies as the main sedimentary facies. Fuyu reservoir is characterized by strong diagenesis, relatively compact lithology, average separation coefficient of 3.7, median granularity of 0.07-0.14mm, and muddy cementation. The core permeability of 50% Fuyu reservoir in the block is less than 0.1 脳 10 ~ (-3) 渭 m ~ (-2), the permeability distribution is dispersed, and its anisotropy is serious, which leads to the supercritical CO_2 with high mobility easily occurring in the formation, and the invalid cycle is serious. Especially when the permeability is less than 1 脳 10 ~ (-3) 渭 m ~ 2, the water sensitivity of the core is moderate and strong, which is aggravated by water injection in the early stage. In combination with these geological conditions of the target layer, it is determined that the channeling sealing system suitable for this kind of ultra-low permeability gas drive reservoir is foam type channeling sealing system. The foam system has low viscosity and its low surface interfacial tension can realize its effective injection and foaming plays the role of plugging gas and not plugging oil in the formation. At the same time, the low molecular weight products were selected according to the characteristics of low porosity and low permeability of the block, and the viscosity of the system was only 8-12 mPa s. This block belongs to high geothermal gradient reservoir, and the reservoir temperature is more than 80 鈩，
本文编号：2418452
[Abstract]:Along with the development of CO_2 injection, the gas channeling problem has been exposed in Daqing C area in recent years. The ineffective cycle of CO_2 is serious and the oil production is decreasing. Therefore, reasonable and effective gas channeling control technology is urgently needed to assist the development of CO_2 flooding test area. According to the geological conditions of the target bed in the study area, the causes and difficulties of gas channeling are analyzed, the channeling sealing agent is developed, and the field test of channeling sealing is carried out. In Daqing C area, the structure is located in Songliao basin, with fluvial and delta facies as the main sedimentary facies. Fuyu reservoir is characterized by strong diagenesis, relatively compact lithology, average separation coefficient of 3.7, median granularity of 0.07-0.14mm, and muddy cementation. The core permeability of 50% Fuyu reservoir in the block is less than 0.1 脳 10 ~ (-3) 渭 m ~ (-2), the permeability distribution is dispersed, and its anisotropy is serious, which leads to the supercritical CO_2 with high mobility easily occurring in the formation, and the invalid cycle is serious. Especially when the permeability is less than 1 脳 10 ~ (-3) 渭 m ~ 2, the water sensitivity of the core is moderate and strong, which is aggravated by water injection in the early stage. In combination with these geological conditions of the target layer, it is determined that the channeling sealing system suitable for this kind of ultra-low permeability gas drive reservoir is foam type channeling sealing system. The foam system has low viscosity and its low surface interfacial tension can realize its effective injection and foaming plays the role of plugging gas and not plugging oil in the formation. At the same time, the low molecular weight products were selected according to the characteristics of low porosity and low permeability of the block, and the viscosity of the system was only 8-12 mPa s. This block belongs to high geothermal gradient reservoir, and the reservoir temperature is more than 80 鈩，
本文编号：2418452
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