Reservoir Characteristics And Fracability Research, Case Study On Well YuYe-1

Domestic scholars focuse on the accumulation mechanism, enrichment conditions and favorable region of shale gas. But studies on reservoir stimulation methods are fewer.Weak research on shale reservoir restricts the progress of shale gas development in China. The reservoir characteristics research and evaluate shale fracability of Well YuYe-1 is of great significance to guide the further development.Shale gas well hydraulic fracturing techniques include multistage fracturing, water fracturing, hydrojet fracturing, refracturing and simultaneous fracturing. Multistage fracturing is suitable for long horizontal well with many producing layers; Water fracturing applied to the well which clay content is moderate and natural fractures in the reservoir is plentiful; Hydrojet fracturing is not restricted by the completion method and especially suitable for openhole horizontal wells; Refracturing is usually used in later development stage after the initial fracturing results decline and it is suitable for the well that first fracturing didn’t get desirable results; Simultaneous fracturing is suitable for two or more parallel wells which are in close proximity.This paper presents fracability of shale and its evaluation methods at the first time in China and applies it to Well YuYe-1. The key parameters of shale fracability contain the reservoir depth, fractures, brittleness, quartz content. This paper calculates the weights of the four different parameters according to the principle of Analytic Hierarchy Process, and standardizes the dimension of the four different parameters according to the principle of range transformation. The fracability index of Well YuYe-1 is 0.524 which is much lower than Barnett shale.Barnett shale fracability index is 0.655.Longmaxi formation depth in Southeast of Chongqing increases from southeast to northwest areas gradually .Quartz content and the brittleness increases from the Southwest to northeast and the highest value is between Pengshui and Qianjiang. This paper optimized Lianhu-Canggou-Wulong (Except Wulong county and its edge, Canggou and its edge), Pingan-Pengshui-Huangan, Shaba-Sangtuo as the higer fracability region and the fracability increases from southwest to northeast.The fracability index is over 0.594.There are two aspects for hydraulic fracturing of shale gas well in China at this stage. The old wells which have good shale gas shows during drilling and get a certain production after reconstruction can be refracted using modern hydraulic fracturing technology. Taking technical characteristics of hydraulic fracturing and the cost into consideration, the favorable reservoir over 1500 m or exploration shallow wells could be fractured with nitrogen foam and high-energy gas. The reservoir between 1500 m and 3000 m, water fracturing can be used and water multistage fracturing could be used in thick shale reservoirs. However, the reservoir below 3000 m can not be taken into consideration at present. Simultaneous fracturing is necessary of the large-scale shale gas development.