水平井高效开采Class 3天然气水合物研究  

A simulation study of Class Ⅲ hydrate production with a high efficiency through the depressurization recovery and thermal stimulation in horizontal wells

作　　者：樊栓狮[1] 杨圣文[1] 温永刚[1] 王燕鸿[1] 郎雪梅[1] 

机构地区：[1]华南理工大学化学与化工学院.传热强化与过程节能教育部重点实验室

出　　处：《天然气工业》2013年第7期36-42,共7页Natural Gas Industry

基　　金：国家重点基础研究计划(973计划)项目"南海沉积物中天然气水合物形成动力学研究"(编号:2009CB219504-03);国家自然科学基金"提高天然气水合物生成速率强化传热传质研究"(编号:51176051);中国石油科技创新基金项目(编号:2012D-5006-0210)

摘　　要：中国目前所发现的水合物藏缺乏下伏流动层,比较接近有上、下盖层的Class 3水合物,业内对其开采的经济性和能效比有质疑且相关研究成果鲜见。为此,采用HydrateResSim模拟水平井加热减压联合开采Class 3水合物,研究了其开采的能效比、气水比、采收率等参数。首先定义水合物开采所获得的天然气的热值和水合物开采过程输入物藏热量之比为水合物开采的能效比(EER),采用能效比对水合物开采过程进行评价;然后,设定开采井的温度为42℃,在0.2 p0(p0为水合物藏初始压力,1.383×107Pa)、0.5 p0、0.8 p03种压力条件下进行水平井加热减压联合开采模拟。结果发现:①开采前期能量消耗大,产水量多;②只有在0.2 p0、42℃条件下,气水比长期大于100,采收率在50%左右,同时,EER达到188;③而0.5 p0和0.8 p0条件下的开采指标较0.2 p0小很多。进一步分析0.2 p0、42℃条件下水合物开采过程中井内热流数据,得到加热只分解了5.28%的水合物,其他大量水合物由减压驱动力分解,因而能效比较高。结论认为:水平井加热减压联合的方法能够高效开采Class 3水合物。Natural gas hydrate is a potential and alternative energy source. For lack of the flowing layers underlain, the discovered hydrate reservoirs in China belong to Class Ill hydrate pools, which have top and bottom covered layers. However, most domestic scholars still doubt about the economic possibility and energy efficiency ratio （EER） of Class UI hydrate production and no such liter- atures have ever been found yet. In view of this, the reservoir simulation tool HydrateResSim was adopted to simulate the production process of Class UI hydrate through the depressurization recovery and thermal stimulation in a horizontal well, which aims to study the indicators such as EER, gas-water ratio, the gas recovery rate, etc. First, EER, defined by the ratio between energy output from hydrate and energy input to dissociate hydrate, was applied to evaluate the possibility of hydrate dissociation through the above two recovery methods in this case study. Then, the simulation conditions were as follows in the horizontal well： well temperature was 42℃; well pressure was 0.2 P0, 0.5 P0, 0.8 P0 respectively. P0, the initial pressure of a hydrate reservoir, was equal to 1. 383×10^7 Pa. The following findings were concluded, a. At the early stage of hydrate production, there is huge energy consumption needed and a great volume of water produced, b. Only when the well temperature is 42℃ and the well pressure 0.2 P0, the gas-water ratio will be kept above 100 for a long time, the gas recovery rate about 50%, and the EER up to 188, the indicators of which are all much bigger than those under the other two well pressures. Furthermore, through the analysis of other heat flow values in the case of 0.2 P0, it was found that only about 5.28% hydrate was dissociated by the thermal stimulation; and the others were all by the depressurization recovery. That could explain why the EER in this case is much higher. In conclusion, this study proves that the depressurization recovery and thermal stimulation in a horizontal well will be a

关 键 词：CLASS 3天然气水合物 水平井 加热减压联合开采 气水比 采收率 能效比 高效开采 

分 类 号：TE37[石油与天然气工程—油气田开发工程]