四川盆地北部地区巴中1HF井侏罗系河道砂岩油气勘探突破及意义

Breakthrough in oil and gas exploration of Jurassic channel sandstone in Well Bazhong 1HF in northern Sichuan Basin and its significance

2023年1月,四川盆地北部地区(以下简称川北地区)巴中1HF井首次在侏罗系河道砂岩获得超百立方米的高产工业油流,实现了川北地区侏罗系河道砂岩油气勘探的重大突破。为了进一步支撑该地区油气的深化勘探,基于巴中1HF井的最新勘探成果,分析了川北地区侏罗系凉高山组的沉积特征、储层特征与控制因素,开展了油气藏特征与油气源对比分析,攻关形成了针对多期纵向叠置、横向迁移、储层薄、非均质性强的河道砂岩油气勘探关键技术,明确了川北地区凉高山组下一步的油气勘探方向。研究结果表明:(1)巴中地区凉二段发育多期三角洲前缘水下分流河道砂体,砂岩厚度约25 m,平均孔隙度为5.6%,孔隙类型以原生粒间孔、长石/岩屑粒内溶孔为主,孔喉结构好,优质储层发育受水下分流河道沉积微相控制;(2)凉二段油气藏为高含油凝析气藏/挥发性油藏,油气主要来自凉一段和凉二段的半深湖相泥页岩;(3)凉二段上部及凉三段河道砂体叠置连片发育,源储匹配好,具有近源成藏、超压富油气的聚集特征;(4)针对多期纵向叠置、横向迁移、储层薄、非均质性强的河道砂岩,形成的以“高频层序地层切片、分频、相带控制的波形指示反演”储层预测技术实现了对窄细河道砂岩“甜点”目标精细描述,形成的“密切割+复合暂堵+高强度加砂+渗吸增油”的压裂关键技术实现了河道砂岩储层的规模改造。结论认为,巴中1HF井凉高山组油气勘探的突破进一步揭示了四川盆地侏罗系油气勘探的巨大潜力,对于加快四川盆地侏罗系河道砂岩油气勘探开发起到了积极的推动作用。

In January 2023,Well Bazhong 1HF in the northern Sichuan Basin obtained high-yield industrial oil flow of over 100 cubic meters from the Jurassic channel sandstone for the first time,realizing a major breakthrough.In order to provide more support for further oil and gas exploration in this area,this paper analyzes the sedimentary and reservoir characteristics of the Jurassic Lianggaoshan Formation in Bazhong area of northern Sichuan Basin and their control factors based on the exploration achievements of Well Bazhong 1HF.Then,oil and gas reservoir characteristics and oil and gas sources are comparatively analyzed.Finally,the key technologies for the exploration of channel sandstone oil and gas with multi-stage vertical superimposition,lateral migration,thin reservoir and strong heterogeneity are researched and developed,and the next oil and gas exploration direction in the Lianggaoshan Formation of northern Sichuan Basin is pointed out.And the following research results are obtained.First,in the second Member of Lianggaoshan Formation("Liang 2 Member"for short)in Bazhong area,multi-stage underwater distributary sand bodies of delta front are developed with sandstone thickness of about 25 m and average porosity of 5.6%.The pore types are mainly primary intergranular pores and feldspar/debris intragranular dissolved pores,the pore throat structure is good,and the development of good-quality reservoirs is controlled by the sedimentary microfacies of underwater distributary channel.Second,the oil and gas reservoir of Liang 2 Member is a highly oil-bearing condensate gas reservoir/volatile oil reservoir,whose oil and gas is mainly sourced from the semi-deep lacustrine shale of Liang 1 and 2 Members.Third,channel sand bodies are superimposed and developed continuously in the upper part of Liang 2 Member and the Liang 3 Member,and the source-reservoir configuration is good,with the characteristics of near-source hydrocarbon accumulation and overpressure hydrocarbon enrichment.Fourth,for the channel sandstones with multi-stage vertical superimposition,lateral migration,thin reservoir and strong heterogeneity,the reservoir prediction technology of"high-frequency sequence stratigraphy slice,seismic frequency decomposition and facies-constrained seismic waveform indication inversion"is developed to precisely characterize the"sweet spot"target of narrow channel sandstone,and the key fracturing technology of"dense cutting+composite temporary plugging+high-intensity proppant injection+imbibition and oil-increasing"is formed to realize the large-scale reconstruction of channel sandstone reservoir.In conclusion,the breakthrough of Well Bazhong 1HF in the exploration of Lianggaoshan Formation oil and gas in Bazhong area reveals the huge potential of Jurassic oil and gas exploration in the Sichuan Basin,and plays a positive role in promoting the exploration and development of the Jurassic channel sandstone oil and gas in the Sichuan Basin.