摘要
为了分析渤海边际油田小井眼井壁岩石应力稳定状态,确定不同井眼尺寸下的临界出砂压差,为边际油田小井眼油井防砂提供理论参考,基于岩石强度的尺寸效应理论,建立了临界出砂压差的预测模型,采用有限元软件分析了尺寸效应对近井地带及井周应力的影响规律,讨论了生产过程中井壁岩石塑性区的扩展规律。研究表明:尺寸效应对近井地带及井周应力状态有一定的影响,随着生产压差增大,设定路径上的径向应力呈增大趋势,最终逐渐趋于恒定值,而切向应力呈先增大后减小的规律,生产压差越大、切向应力峰值越高。生产压差相同时,大井眼周围塑性区面积大于小井眼周围塑性区面积,而切向应力恰好相反,说明小井眼井壁更为稳定。通过考虑尺寸效应对砂岩地层出砂数值模拟研究,证明小井眼具有较大临界出砂压差,对边际油田的开发具有一定的指导意义。
In order to analyze the stable rock stress state of the slim-hole wall in Bohai marginal oilfields,determine the critical sand production pressure difference under different well sizes,and provide theoretical reference for the sand control of the slim-hole oil well in the marginal oilfields,the prediction model of critical sand production pressure difference was established based on the size effect theory of rock strength.The influence of the borehole size effect on the near-well zone and well-wall stress was analyzed by using finite element software,and the expansion law of the plastic zone around well bore in the production process was discussed.The study shows that the size effect has certain influence on the near-well zone and well-wall stress state.With the increase of production pressure difference,the radial stress on the set path tends to increase,and finally tends to be constant.However,the tangential stress increases first and then decreases.The greater the production pressure difference,the higher the peak value of the tangential stress.Under the same production pressure difference,the area of plastic zone around the big borehole is larger than that around the small borehole,while the tangential stress is just the opposite,which shows that the wall of the small borehole is more stable.The numerical simulation of sand production in sandstone formation considering the borehole size effect proves that the critical sand production pressure difference of slim hole is larger,which has certain guiding significance for the development of marginal oil fields.
作者
龚宁
林海
李进
徐涛
贾立新
Gong Ning;Lin Hai;Li Jin;Xu Tao;Jia Lixin(Tianjin Branch,CNOOC(China)Co.,Ltd.,Tianjin 300459,China)
出处
《石油工业技术监督》
2020年第7期1-4,共4页
Technology Supervision in Petroleum Industry
基金
国家“十三五”重大科技专项“渤海油田高效钻完井及配套技术示范工程”(编号:2016ZX05058002)。
关键词
小井眼
尺寸效应
临界生产压差
数值模拟
slim-hole
size effect
critical sand production pressure difference
numerical simulation
