四川盆地上震旦统灯四段气藏提高单井产量的技术措施

四川盆地上震旦统灯影组四段气藏的储层类型多样、非均质性强,前期探井开发效果较差,亟需研发适合于不同储层类型的增产改造技术措施,以提高单井产量。为此,开展了5个方面的优化研究,提出了有针对性的技术措施:①依据储层特征、缝洞发育程度等与产能的相关性研究结果,优选出了灯四段以斜井为主兼顾纵向各层储量有效动用的方案;②采用改造—完井—投产一体化管柱进行储层改造,降低储层伤害、提高试油效率;③充分考虑井壁稳定性、储层改造的需要及对储层的伤害,确定裂缝、孔洞发育储层采用裸眼完井、孔隙型储层采用射孔完井;④基于酸与岩石反应实验结果及酸蚀裂缝刻蚀形态等成果优选出了高温胶凝酸为主体酸液,自生酸前置液为深度酸压主体前置液;⑤以储层特征为基础,提出分别针对裂缝—溶洞型、孔隙—溶洞型和孔隙型储层的缓速酸酸压、前置液酸压和复杂网缝酸压3套工艺。现场实施上述技术措施31口井,平均单井获得井口测试天然气产量68.33×10~4 m~3/d,与前期的探井相比,平均单井增加井口测试天然气产量22.85×10~4 m~3/d。

Technological measures for improving single-well productivity of gas reservoirs of Upper Sinian Deng 4 Member in the Sichuan Basin

In the fourth Member of Upper Sinian Dengying Fm (Deng 4 Member) in the Sichuan Basin, there are various types of reservoirs with strong heterogeneity, and the early exploratory wells are poorly developed. Therefore, it is in urgent need to research and develop stimulation technologies and measures suitable for different types of reservoirs so as to increase single-well productivity. In this paper, an optimization study was carried out in five aspects, and technical measures were put forward correspondingly. First, according to the analysis on the correlation between the productivity and the reservoir characteristics and fracture-vug development degree, it was proposed to drill deviated wells dominantly in Deng 4 Member and give consideration to the effective production of reserves of vertical layers. Second, the integrated string of stimulation–well completion–production was adopted for reservoir stimulation to reduce reservoir damage and improve well test efficiency. Third, sufficient consideration was given to borehole wall stability, reservoir stimulation and the damage to reservoirs before open hole completion suitable for reservoirs with developed fractures and vugs and perforated completion suitable for porous reservoirs were performed. Fourth, based on acid/rock reaction experiment results and the etch forms of etched fractures, it is determined to take high-temperature gelling acid as the host acid and self-generating acid prepad as the host prepad fluid for in-depth acid fracturing. And fifth, on the basis of reservoir characteristics, it is recommended to apply retarded acid fracturing in fracture-vug reservoirs, prepad acid fracturing in pore-vug reservoirs and complex fracture net based acid fracturing in porous reservoirs. These measures are practically taken at 31 wells and their single-well natural gas production rates measured at the wellhead average 68.33×104 m3/d, which is 22.85×104 m3/d higher than those of early exploration wells.