川东侏罗系——四川盆地亟待重视的一个致密油气新领域

Jurassic tight oil & gas resources in East Sichuan Basin: A new exploration target

四川盆地侏罗系油气勘探开发主要集中在川中和川西地区,长期以来对川东地区侏罗系蕴藏的丰富油气资源与勘探潜力未能给予足够的重视。在四川盆地近60年的勘探开发历史中,川东侏罗系至今几乎还是一片尚待开发的油气资源处女地。事实上,川东地区许多钻井在钻遇侏罗系时都曾发现过大量的油气显示,少量钻井经测试甚至获得过工业油气流。初步研究结果表明,川东地区侏罗系具有与川中地区侏罗系十分相似的油气成藏条件,其烃源岩厚度大、储层致密、油气资源丰富,是四川盆地内除川中侏罗系之外还有希望找到原生油藏的一个有利地区。建议尽快将川东侏罗系油气藏作为四川盆地一个重要的致密油气勘探新领域,开展整体评价研究,实施专层勘探,并采用非常规油气勘探评价技术与方法,在油气保存条件较好的低缓、潜伏构造以及宽缓的向斜区,优选有利区块,开展水平井钻井与储层改造先导性试验。与目前在渝东南等构造复杂区开展的页岩气勘探相比,川东侏罗系油气勘探的地质风险与开采成本将更低,探明油气资源并投入商业开发的成功率与机遇更大,更具有找到规模性油气田(藏)的现实必然性。

The Jurassic hydrocarbon exploration and development have always focused on the middle and west of the Sichuan Basin but ignored the huge hydrocarbon resources and great exploration potential in the east of this basin.This virgin land has been left there unexplored and undeveloped over the past almost 6 decades.In reality,a great volume of oil and gas shows have been discovered in many wells targeting the Jurassic pay zones in East Sichuan Basin,even industrial oil and gas flows have been achieved in a few cases.A preliminary study shows that there are good conditions in this virgin land for the formation of hydrocarbon reservoirs,very similar to those in Middle Sichuan Basin: great thickness of source rocks,tight reservoirs,rich hydrocarbon resources,etc.Thus,this virgin land will become another prospective area favorable for the exploration of original oil and gas reservoirs in this basin.Therefore,this paper suggests that the Jurassic tight oil and gas reservoirs in East Sichuan Basin should be taken as an important new target;overall assessment and specific Jurassic exploration should be carried out;pilot tests for horizontal wells and reservoir stimulation should be made in the low,buried structures or the wide synclines with better preserving conditions by use of such exploration evaluation technologies and methods for the discovery and exploitation of unconventional hydrocarbon resources.Compared with shale gas exploration in the complex areas like the structure in the southeastern Chongqing,oil and gas exploration in the Jurassic of East Sichuan Basin is of lower geological risk and exploitation cost but of higher success rate and opportunity of delivering oil and gas resources and putting into commercial production,therefore it is more realistic and inevitable to discover large-scale hydrocarbon reservoirs or fields.