高温高压气藏地层水盐析引起的储层伤害  被引量:13

Reservoir damages caused by formation-water salt precipitation in high-pressure and high-temperature gas reservoirs

在线阅读下载全文

作  者:汤勇[1] 杜志敏[1] 蒋红梅[2] 孙雷[1] 

机构地区:[1]西南石油大学油气藏地质及开发工程国家重点实验室,四川成都610500 [2]中国石化胜利油田公司河口采油厂,山东东营257200

出  处:《石油学报》2012年第5期859-863,共5页Acta Petrolei Sinica

基  金:国家自然科学基金项目(No.50604011)资助

摘  要:针对高温高压气藏烃-水互溶加大,降压开采过程中近井带地层水的大量蒸发极易导致盐析产生,进而堵塞储层、降低气井产能的问题,通过室内实验进行了地层水蒸发盐析对储层物性影响研究,分析了地层水蒸发导致盐析前后岩心渗透率的降低程度。利用扫描电镜观测析出的结晶盐在孔道中的产状,通过流动孔隙结构实验研究岩心中发生盐析后孔隙分布的变化特征。结果表明:盐析致使地层孔隙度最大降幅约15%,渗透率最高降幅达83%;地层水矿化度越高,地层渗透率降低程度越大;地层原始渗透率越低,降低程度越大;不同水型的地层水,其盐析产物不同,以NaCl为主。盐析后,结晶盐填充了岩心中的小孔隙,小孔喉在岩心中的比例明显减少,渗流通道减小,有的甚至完全被堵塞;盐析对小孔径岩心所造成的影响远远大于大孔径岩心。因此,高温高压高矿化度地层水的气藏开发中必须考虑地层水的蒸发以及盐析可能造成的伤害。A high mutual solubility of hydrocarbons and formation waters in a high-temperature and high-pressure gas reservoir may readily cause salt precipitation when formation waters in the immediate vicinity of wellbore evaporate largely during the blowdown process, which may further plug the reservoir and impair gas-well productivity. The effect of formation-water evaporation and salt precipitation on physical properties of reservoirs was studied through laboratory experiments and the reducing level of core permeabil- ity before and after salt precipitation was analyzed as well. The occurrence of crystal salt in pore passages was observed using scan- ning electron microscopy and variation features of the pore distribution in cores after salt precipitation were studied by means of flow micro-p0re structure experiments. The result shows that porosity reduces about 15 ~ and permeability decreases about 83 ~ at maxi- mum because of salt precipitation. The higher the salinity of formation waters, the more greatly the level of formation permeability reduces, and the lower the initial permeability of formations, the greater the permeability reduction. Different types of formation wa- ters produce different salt crystals, though mainly with NaC1. After salt precipitation, fine pores are often filled with salt crystals and the proportion of small pore throats in cores reduces significantly, resulting in seepage passages narrowing down and even occa- sionally being blocked completely. Moreover, the impact of salt precipitation on fine pores in cores is generally greater than that on large pores. Therefore, the formation damage caused by formation water evaporation and salt precipitation must be taken into consid- eration in the exploitation of HP/HT gas reservoirs with high-salinity formation waters.

关 键 词:高温高压气藏 地层水蒸发 盐析 储层伤害 产能 

分 类 号:TE124.2[石油与天然气工程—油气勘探]

 

参考文献:

正在载入数据...

 

二级参考文献:

正在载入数据...

 

耦合文献:

正在载入数据...

 

引证文献:

正在载入数据...

 

二级引证文献:

正在载入数据...

 

同被引文献:

正在载入数据...

 

相关期刊文献:

正在载入数据...

相关的主题
相关的作者对象
相关的机构对象