黔西松河井田龙潭煤系煤层气-致密气成藏特征及共探共采技术

Reservoir formation characteristics and co-exploration and concurrent production technology of Longtan coal measure coalbed methane and tight gas in Songhe field,western Guizhou

基于煤系气共探共采示范工程,分析了黔西松河井田龙潭煤系煤层气-致密气赋存特征及开发条件,探讨了煤系气共探共采的适配性技术工艺。研究表明:井田煤系气主要赋存于龙潭煤系多个煤层及临近细砂岩、粉砂岩中,具备多煤层共采、煤系气共采的资源及开发条件。煤储层具有高温、超压、高含气量、含气高-过饱和的特点,适宜进行煤层气地面开发;但在区域高地应力背景下,裂隙闭合、矿物充填等原因导致储层原始渗透性差,煤系气地面开发需进行储层改造。气测录井、裸眼综合测井及含气层综合评价是井田煤系气共探共采中发现、认识、评价含气层及产气层段优选的关键技术,可为煤系气共探共采方案制定提供依据。在丛式井组开发模式下,"小层射孔、组段压裂、合层排采"系列工艺与井田地形地质条件相匹配,可显著提高多煤层共采、煤系气共探共采的工程效果。

Based on a demonstration project of coal-formed gas co-exploration and concurrent production,this paper analysed the occurrence characteristics and development conditions of Longtan coal measure coalbed methane and tight gas,and discussed the suitable technology for the coal-formed gas co-exploration and concurrent production.The results show that coal-formed gas is mainly hosted in the multiple coal seams of Longtan coal measures and closes to the gas bearing formation which contains fine sandstone and siltstone; it has enough resource and favorable development conditions that include the multi-layer commingling development and the concurrent production of coal-formed gas.The coal reservoir with the characteristics of high temperature,overpressure,high gas content and gas supersaturated is suitableto coalbed methane ground development; but some factors including the reservoir fracture closing and mineral filling could lead to the lower original permeability at high ground stress area.Therefore,the coal-formed gas ground development needs to carry out the reservoir reconstruction.The key technology of discovering,recognizing and evaluating the optimization of gas bearing and producing layers in field coal-formed gas co-exploration and concurrent production are gas logging,uncorrected comprehensive logging and the comprehensive evaluation of gas bearing layer.They provide the basis for establishing the coal-formed gas co-exploration and concurrent production scheme.In the development mode of collecting well group,the technologies including the small-layer perforating,group-segment fracturing and multi-layer drainage need to match with the topography and geology conditions of the field. Thus it can significantly improve the engineering effect of the multi-layer commingling development and the coal-formed gas co-exploration and concurrent production.