天然气水合物的开采——以马利克钻井为例

Gas hydrates production——in case of mallik test well

马利克水合物钻井项目是以加拿大为主执行的一个国际大陆钻探项目.该项目的目标是在多学科科研框架内,尝试几种水合物分解激发方法,并进行水合物连续生产效应评价.钻井位置选在加拿大西北地区贝夫特大陆边缘马更些三角洲的最北端,这里是加拿大油气储量最为丰富的地区之一.本项目共完成三口间距40米的钻井,中间为生产井,用于水合物的生产实验,两侧为观测井,用于水合物生产之前、生产中及生产之后的各种观测.在生产井中使用减压法、热激发法以及两者组合进行了水合物的短期生产开采实验.在马利克钻探之前,人们通过计算机模拟来评价热激发和降压法进行水合物开发的评价.计算机模拟结果显示,在技术上,水合物的产气速率完全可以达到作为资源开发的要求.但利用这种方法进行水合物开采,在经济上是否合算,则没有可靠的评估和先验的知识.马利克的研究钻探首次证实从水合物储层进行天然气体生产在技术和经济上都是可行的.实验证明,在气体采收过程中减压比单纯加温能更快地产生气体,而加温和减压组合则能高效率地从水合物储层中产生气体.

Mallik gas hydrate production test well was the first International Continental Scientific Drilling Program （ICDP） executed within Canada and leaded by Canada. The purposes of this program were to conduct short term but continuous gas hydrate production in several different ways and to assess the environmental implications of gas hydrate production activity under a multidisciplinary frame. The well location was chosen on the Beaufort Continental Margin, at the north most Mackenzie Delta, which is an area rich of oil and gas in Northwest Territories of Canada. Three holes with 40 m apart were drilled. The middle served as the production well, while the other two besides as the observation wells. Pressure-drawdown and thermal-stimulation were used on the middle hole during the production test. Before this program, based on the produc tion modeling studies, we only known that by pressure-drawdown and thermal-stimulation, gas hydrate dissociation could be fast enough for the gas production, but the economic feasibility remain unknown. The Mallik test result for the first time proved the economic feasibility of gas hydrate production by means of either of pressure-drawdown or thermal stimulation or the two methods combined. The result also shown that when combined the pressure-drawdown and thermal stimulation together we will get the highest gas production rate.