张晓娜, 康永尚, 姜杉钰, 顾娇杨, 孙晗森. 沁水盆地柿庄区块3号煤层压裂曲线类型及其成因机制[J]. 煤炭学报, 2017, 42(S2): 443-453. DOI: 10.13225/j.cnki.jccs.2017.1227
引用本文: 张晓娜, 康永尚, 姜杉钰, 顾娇杨, 孙晗森. 沁水盆地柿庄区块3号煤层压裂曲线类型及其成因机制[J]. 煤炭学报, 2017, 42(S2): 443-453. DOI: 10.13225/j.cnki.jccs.2017.1227
ZHANG Xiaona, KANG Yongshang, JIANG Shanyu, GU Jiaoyang, SUN Hansen. Fracturing curve types and their formation mechanism of coal seam 3 in Shizhuang block, Qinshui basin[J]. Journal of China Coal Society, 2017, 42(S2): 443-453. DOI: 10.13225/j.cnki.jccs.2017.1227
Citation: ZHANG Xiaona, KANG Yongshang, JIANG Shanyu, GU Jiaoyang, SUN Hansen. Fracturing curve types and their formation mechanism of coal seam 3 in Shizhuang block, Qinshui basin[J]. Journal of China Coal Society, 2017, 42(S2): 443-453. DOI: 10.13225/j.cnki.jccs.2017.1227

沁水盆地柿庄区块3号煤层压裂曲线类型及其成因机制

Fracturing curve types and their formation mechanism of coal seam 3 in Shizhuang block, Qinshui basin

  • 摘要: 煤层气井压裂曲线提供了煤储层中压裂缝扩展的动态信息,压裂曲线的形态特征可在一定程度上反映出煤储层的压裂效果。基于柿庄区块单层压裂3号煤层的45口煤层气井的压裂资料,划分了压裂曲线类型,探讨了压裂曲线类型和排采效果的关系,并首次从地应力类型和压裂缝类型的角度深入分析了不同类型压裂曲线的成因机制。研究表明:根据携砂液阶段形态特征,柿庄区块3号煤层压裂曲线可划分为稳定、下降、上升和波动4种类型。稳定型和下降型曲线对应的煤层气井的排采效果一般较好,而波动型和上升型曲线对应的煤层气井的排采效果往往较差。地应力类型通过影响压裂缝形态影响压裂曲线类型,在II类(σH > σh > σv)地应力区域,多发育以水平压裂缝为主的“T”型或“工”型压裂缝系统,容易形成上升型或波动型压裂曲线;而在III类(σH > σv > σh)或I类(σv > σH > σh)地应力区域,多发育垂直压裂缝或以垂直压裂缝为主的“T”型或“工”型压裂缝系统,容易形成下降型、稳定型或波动型压裂曲线。柿庄区块3号煤层的压裂曲线类型平面上呈现出一定的规律性,在以II类(σH > σh > σv)或III类(σH > σv > σh)地应力类型为主的东部,出现稳定、下降、上升和波动多种压裂曲线类型;而在以I类(σv > σH > σh)地应力类型为主的西部,压裂曲线类型单一,多为稳定型和波动型。

     

    Abstract: Fracturing curve of coalbed methane (CBM) wells offers lots of dynamic information of fracture extension, which is able to reflect fracturing effect.Based on the fracturing data of 45 CBM wells where coal seam 3 was only fractured and drained in Shizhuang CBM block, fracturing curve types were classified and the relationship between fracturing curve types and gas production of CBM wells were discussed.Most importantly, the formation mechanism of fracturing curve types were first time discussed.The study shows that the fracturing curves of coal seam 3 in Shizhuang CBM block can be divided, according to the morphological characteristics during sand-bearing stage, into four types including stable, descending, rising and fluctuating.The stable and descending curves always lead to high gas productions.However, the rising and fluctuating curves are usually corresponding to low gas productions.The in-situ stress types and related hydraulic fracture types have a controlling effect on fracturing curve types.In a field of in-situ stress type II (σH > σh > σv), horizontal hydraulic fractures accompanied with “T”-shape or “工”-shape complex fractures are developed and results in rising and fluctuating fracturing curves.However, in a region where the in-situ stress type is either type III(σH > σv > σh)or type I (σv > σH > σh), vertical hydraulic fractures or vertical hydraulic fractures accompanied with “T”-shape or “工”-shape complex fractures are developed and results in stable and descending fracturing curves.The distribution of fracturing curve types in Shizhuang CBM block shows a certain regularity.In the eastern part of the block where in-situ stress type II (σH > σh > σv) or type III(σH > σv > σh)was identified, the stable, descending, rising and fluctuating fracturing curve types were observed.In the western part of the block where in-situ stress type I (σv > σH > σh) were identified, only the stable and fluctuating fracturing curve types were observed.

     

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