单一低渗煤层水力压冲增透抽采瓦斯技术

Hydraulic Pressure Burst Increasing Permeability Technology for Single Low Permeability Coal Seam

井下钻孔水力压裂作为单一低渗煤层增透抽采的有效技术,近年来得到了较广泛应用,但受限于井下空间及设备能力,难以实现大排量及加支撑剂压裂,存在压裂范围有限、裂缝不均一、易闭合等问题。因此提出了水力压冲增透抽采瓦斯技术,即以"单元压裂缝网增透,单孔出煤卸压增透"为主要思路,在控制单元内"先压",使单元内的裂缝开启、延伸、沟通,初次形成"裂缝",在"裂缝"的基础上"后冲"进一步形成均匀的"缝网"并出煤卸压,这样既避免了单压的不均匀性,又增大了单冲的出煤量,在单元内形成有助于抽采的"立体缝网"。试验表明,单元水力压冲抽采纯量是是常规抽采钻孔的10.6倍,水力压裂的12倍,水力冲孔的2.78倍。

Underground drilling hydraulic fracturing as a kind of increasing permeability effective extraction technology for single low gas permeability coal seam has the widespread application, but confined to the underground space and equipment ability, it is difficult to achieve large displacement or add proppant fracturing; crack is not uniform and easy to closing, hydraulic pressure burst increasing permeability extraction technology is proposed in this paper. The technology, taking ＂ cell increasing permeability fracture network, the coal unloading single -hole increasing permeability＂ as the main thought, ＂pressure＂ inside the control unit makes the unit within the cracks open, extension, connection, and form a ＂crack＂ for the first time, on the basis of the ＂cracks＂ after ＂blunt＂ , it forms a uniform ＂net＂ slot and the coal unloading further, which avoids single pressure unevenness, increases the single shot landings, helps to form extraction in the unit ＂stereo net＂. Hydraulic pressure burst test shows that unit extraction from scalar is 10.6 times that of the conventional extraction from drilling, hydraulic fracturing of 12 times, 2.78 times that of the hydraulic punching.