【摘要】：伴隨注CO_2開發(fā)的推進(jìn),大慶C區(qū)近年來暴露出了氣竄的問題,CO_2無效循環(huán)嚴(yán)重,產(chǎn)油量下降。因此急需合理有效的控氣竄技術(shù)來輔助CO_2驅(qū)試驗(yàn)區(qū)的開發(fā)。本文根據(jù)研究區(qū)目的層的地質(zhì)條件,分析了氣竄的原因和難點(diǎn),針對(duì)性的研制了封竄劑,并開展了封竄礦場(chǎng)試驗(yàn)。大慶C區(qū),構(gòu)造位于松遼盆地,以河流-三角洲相為主的沉積,扶余油層成巖作用強(qiáng),巖性相對(duì)致密,分選系數(shù)平均為3.7,粒度中值0.07-0.14mm,以泥質(zhì)膠結(jié)為主。區(qū)塊內(nèi)扶余油層50%的巖心滲透率都小于0.1×10-3μm~2,滲透率分布分散,其各向異性比較嚴(yán)重,導(dǎo)致地層條件下流度很高的超臨界CO_2很容易發(fā)生指進(jìn),無效循環(huán)嚴(yán)重。尤其當(dāng)滲透率小于1×10-3μm~2時(shí),巖心水敏程度為中等偏強(qiáng),前期的注水開發(fā)加劇了這一現(xiàn)象。結(jié)合目的層的這些地質(zhì)條件,確定了適合這種特低滲透氣驅(qū)油藏的封竄體系為泡沫類封竄體系。泡沫體系粘度低,其較低的表界面張力能夠?qū)崿F(xiàn)其有效注入,并在地層內(nèi)發(fā)泡發(fā)揮堵氣不堵油的作用;同時(shí)在起到穩(wěn)泡作用的弱凝膠的選擇上,也針對(duì)區(qū)塊低孔低滲的特點(diǎn)優(yōu)選了低分子量產(chǎn)品,體系基液粘度僅為8-12 mPa·s。該區(qū)塊屬于高地溫梯度油藏,油藏溫度大于80℃,需要選擇耐溫性高的泡沫劑和凝膠,針對(duì)C區(qū)扶余油層這種情況也做出了相應(yīng)的優(yōu)選和調(diào)整,實(shí)現(xiàn)了成膠時(shí)間3-7天可控;發(fā)泡體積550mL;泡沫半衰期60天以上。同時(shí)考慮到平均單井日產(chǎn)油0.3t的低產(chǎn)能,在工藝上取消了成本過高的氣液混注工藝,調(diào)整為由泡沫、凝膠泡沫、防凍防腐段塞構(gòu)成的段塞式封竄工藝,成本較氣液混注工藝節(jié)約了一半�，F(xiàn)場(chǎng)試驗(yàn)2口井,施工成本降低了一半。措施后注入壓力上升了4MPa;注入剖面得到明顯改善,原不吸氣層位得到有效動(dòng)用;連通油井日產(chǎn)油上升明顯,取得較好效果。
[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，

本文編號(hào)：2418452