双鱼石区块栖霞组气藏试采认识及早期开发技术对策

Understanding on production test and technological countermeasures of early development stage:Examples from Qixia gas reservoirs,Shuangyushi block,northwestern Sichuan Basin

基于川西北部地区双鱼石区块栖霞组气藏试采方案执行情况的动态跟踪,结合气藏主要地质特征,梳理气藏主要开发特点,形成了该气藏开发早期初步认识。研究认为:①气藏受成藏条件影响,构造成排成带分布特征明显,划分的6个构造高带中,③、④号高带压力连通;②储层的发育主要受滩相分布及白云岩化作用的控制,具有一定非均质性,试采井井间产能有一定差异;③、④号高带产能明显高于其他高带,且工艺井提高产能效果明显;③气藏存在局部水体,水体来源可能位于构造条带间的低洼部位;④目前气藏基本地质特征与方案设计时认识基本一致,但气水分布认识有所变化,气水关系更为复杂,受试采井数及分布限制,各条带间的连通关系认识、气藏类型定义有待进一步深化;⑤各条带储量动用略不均衡,生产井及后续投产井均集中于③、④号条带,局部采速高,建议调整产量至合理配产规模;⑥应进一步深化岩性边界刻画,加大井控程度较低区域构造、储层预测的研究力度,加快推动储量升级,有效落实储量申报面积及规模,强化超深有水含硫气藏排水采气工艺技术攻关,以支撑下步整体开发方案的编制及科学开发。

For the gas reservoirs of Qixia Formation,Shuangyushi block,northwestern Sichuan Basin,the main development characteristics were summarized and some preliminary understandings on their early development stage were gained on the basis of dynamic tracking the production-test plan and some geological features of Qixia gas reservoirs.It is deemed that in this area,(1)the gas reservoirs may be affected by reservoir-forming conditions,and structures are developed in the form of row and zonation.Among 6 structural high zones,the pressure in No.3 zone is connected with that in No.4 zone;(2)controlled by beach-facies distribution and dolomitization,the reservoirs are heterogeneous,so the productivity in test wells is different to some extent.The productivity in No.3 and No.4 zones is obviously higher than that in other zones.Moreover,the productivity in process wells is obviously improved;(3)there is local waterbody possibly from a depression among structural zones;(4)although the known geological features are basically consistent with the development plan,the understanding on gas-water distribution has been updated.The gas-water relationship is more complex.Controlled by the number and distribution of test wells,the understanding on connectivity among structural zones and the reservoir types should be further clarified;(5)the producing reserves in different zones are slightly uneven.Many existing and future production wells are concentrated in No.3 and No.4 zones,making local production rate high.It is suggested to adjust the production allocation to a reasonable extent;and(6)it is proposed to further describe the lithologic boundary in details,give more efforts to the structure and reservoir prediction in the less well-controlled zone,upgrade the reserves and define the reserve area and scale,and develop the recovery technology suitable for ultra-deep water-bearing sulfur gas reservoirs.All these countermeasures will be constructive to the future development plan.