深水多梯度钻井方法及仿真分析  

A multi-gradient deepwater drilling method and its simulation analysis

作　　者：殷志明 盛磊祥 蒋世全 陈国明[2] 

机构地区：[1]中海油研究总院 [2]中国石油大学(华东)

出　　处：《天然气工业》2012年第11期64-67,119-120,共4页Natural Gas Industry

基　　金：国家科技重大专项"深水钻完井工程技术"(编号:2011ZX05026-01);国家高技术研究发展计划(863计划)"深水表层钻井关键技术及装备研究"(编号:2007AA09A103)

摘　　要：油气勘探开发转向海洋尤其是深海已成为必然。与陆地和浅水相比,由于深水地层特殊的地质沉积条件,深水钻井面临地层压力和破裂压力之间钻井液安全密度窗口窄的问题,井筒压力很难保持在允许的压力窗口之间。为此,介绍了多梯度钻井技术的原理、采用低密度空心球随钻分离注入的实现方法以及其优点:①可以达到较高的空心球浓度(50%～60%),钻井液密度降低明显;②钻井液返回海面后不必分离空心球,可重新循环;③隔水管内钻井液密度和钻杆内钻井液密度相当,不会产生U形管效应;④设备所占空间少,系统操作和控制相对简单。同时,编写了多梯度钻井的仿真程序,分析了空心球注入对压力变化影响效果。结果表明,采用空心球随钻分离注入技术能够实现对井筒压力的优化分配,使井底压力在较长的井段内介于地层压力和破裂压力之间,从而达到简化井身结构的效果。It will be inevitable for hydrocarbon exploration and development to turn from terrestrial strata to see beds,especially deepwater formations.Unlike terrestrial strata or shallow-water formations,deepwater formations with special sedimentary conditions encounter narrow density window of drilling fluid in drilling,which makes it difficult to keep the downhole pressure within an allowable safe range.Therefore,a multi-gradient deepwater drilling method is introduced herein in this paper as well as its principles.Also,the advantages are listed as follows of adopting the lightweight hollow glass spheres injected into the wellbore during drilling process.(1) The drilling fluid could be distinctively diluted by the increased condensation of spheres in the fluid even up to 50%-60%.(2) When the drilling fluid returns to the sea surface,the sphere-mixed fluid can be circulated into use without any need to be separated.(3) The density of drilling fluid in marine riser is almost equivalent to that in drill string so that no U-tube effect ever occurs.(4) The equipment only needs little space and is quite simple to operate and control.Meanwhile,a MGD simulation program is developed to analyze the impact of hollow glass sphere injection on the down-hole pressure.The results show that this method can not only optimally distribute the borehole pressure,which can be kept between the strata pressure and breakdown pressure in a fairly long well interval,but subsequently simplify the well structure.In a word,the multi-gradient deepwater drilling method has a bright prospect in the future.

关 键 词：深水钻井 窄密度窗口 多梯度钻井 空心玻璃球 随钻分离注入 

分 类 号：TE52[石油与天然气工程—油气田开发工程]