Research And Application Of Full-process Underbalanced Drilling Casing Value

The casing valve adopts the downhole isolation method to achieve the under-balanced operation of the whole process.While protecting the reservoir,it can effectively reduce the risk of starting and leaving the drilling operation with pressure,which is one of the necessary technical equipments for achieving underbalanced drilling in the whole process.However,the cost of downhole casing valves of foreign companies is extremely expensive.In order to reduce the production cost and realize the localization of this technology,it is necessary to independently develop downhole casing valves whose performance reach the international advanced level,low service costs,and independent intellectual property rights.Providing equipment and technology for Daqing Oilfield in order to realize downhole isolation method economically and effectively.Based on the investigation of the casing valve technology and the underbalanced drilling technology,this paper has carried out the structural design of the casing valve assembly and the strength check of the corresponding valve body components according to the working principle of the downhole casing valve.The key technologies such as downhole depth,high pressure sealing performance and reciprocating drive structure stability are determined,and corresponding operating procedures are established.On this basis,the laboratory experiments were carried out to optimize performance of clack unit,reasonable assembly,commissioning and performance of the whole set of prototype.and examine the sleeve valve equipment with ground testing,installation,debugging,ground control,the reliability of the operations such as underground movement,and casing valve equipment and related application process whether meet the needs of oilfield process of underbalanced drilling.And sleeve valve equipment the ground testing are verified by field experiments,field installation,debugging,ground control,the reliability of the operations such as underground movement,and casing valve equipment and related application process whether to meet the needs of oilfield process of underbalanced drilling.Through the above research,a relatively complete set of downhole casing valve and its application process have been formed,which has realized the negative pressure of the bottom hole during the whole drilling process.(Including non-compression logging,no pressure downhole into the screen or tail pipe,no pressure downhole into the completion string,etc.).The unobvious balance of the entire process,the obvious effect of protecting the reservoir,reducing the pollution of the reservoir,and increasing the output have been demonstrated,which shows a good application prospect of this technology.