应用模糊数学优选页岩气地质调查井位——以黔西北地区为例

Application of fuzzy mathematics in selecting the favorable location of shale gas survey well:Taking northwest Guizhou as an example

我国当前处于页岩气勘探开发的早–中期阶段,钻探地质调查井是获取资料、发现页岩气的重要手段,尤其在南方下古生界页岩资料空白区,构造、地貌及地面条件极为复杂,井位优选困难很大。以黔西北地区为例,基于大量野外地质调查工作,针对复杂的地质和工程地质条件,初步提出了页岩气调查井位优选的地质和工程地质条件评价标准:在地质条件方面,依据页岩厚度、预测深度、断裂发育程度、地层倾角、距最近露头距离、有机碳含量和成熟度、应力场、脆性矿物含量、水文地质条件及开口层位确定程度等条件将备选井位分为优、良、中、较差和差5个级别;在工程地质条件方面,依据井场地形高差、道路交通、可利用水源、空中障碍物、与村庄/铁路/景区/水库/电网的距离、勘探儀深面积及土地使用情况等要素将备选井位同样分为5个级别;并确定了各个要素在评价中所占的权重。应用模糊数学方法对5口备选调查井井位进行了综合评判与排序,并顺利对优选出的2口调查井实施了钻探,取得了良好效果。该方法对于高效获取空白区页岩气资料,快速发现页岩气,并开展进一步评价工作具有参考意义。

Exploration and development of shale gas in China is now in the early-middle stage.Drilling geological survey well is an important mean to obtain data and discover shale gas in the blank area of Lower Paleozoic shale data in south China.However,due to the extremely complex structure and geomorphic conditions in these areas,it is very difficult to optimize the location of wells.Taking northwest Guizhou as an example,based on a large number of field geological survey work,the evaluation criteria of geological and engineering geological conditions for shale gas survey well location are put forward.In the respects of geological conditions,according to shale thickness,predicted depth,dip angle,fracture density,organic matter features,stress field,hydrogeology and other conditions,the alternative well position is divided into 5 levels:excellent,good,medium,medium deviation and poor.In the respects of engineering geological conditions,according to topographic height difference in well site,road distribution,water resources can be used,air barrier,the distance from the building and other conditions,the alternative well position is divided into the same 5 levels.At the same time,the weight of each element in the evaluation is determined.5 alternative well locations were evaluated and sorted by using fuzzy mathematics.And 2 selected drilling wells have been drilled successfully.This method has reference value for obtaining shale gas data in the blank area,obtaining shale gas quickly and carrying out further evaluation work.