Research On String Of Separate Layer Water Injection Technology In Slim Hole

The large-scale development and construction of Liaohe Oilfield was earlier,and it was initially completed in the early 1980 s.In 1986,it became the third largest oil field in China.Due to the limitation of geological conditions,drilling technology and funds at that time,the borehole size of early completion was mostly five and a half inches.It was established thatφ139.7mm and φ177.8mm were the standard casing sizes of Liaohe Oilfield,and the oil with outer diameter of oil casing less than φ139.7mm was determined water well is called slim hole.After slim hole completion,because the inner diameter of casing is too small,it belongs to unconventional size,there is no relevant mature separate injection technology at home and abroad,and there is also a lack of matching test method in slim hole water injection well.In some domestic oilfields,the general water injection mode and the surface oil casing separate injection mode are mostly adopted.However,due to the limited technology of separate injection level,the separate injection rate of water injection wells will be affected ultimately.At present,there are more than 170 slim hole wells in Liaohe Oilfield.If all these water injection wells realize separate injection,if one water well corresponds to three production wells on average,more than 510 oil wells will increase production because of the effect of separate injection,and solve the problem that a batch of 4-inch,5-inch and 5.5-inch casing change wells can not implement fine stratified water injection.Therefore,it is urgent to study the separate layer water injection string in slim hole.In order to solve the contradiction that water injection wells can not realize multi-layer water injection development in slim holes,this paper takes 4-inch and 5-inch slim hole separate layer water injection technology strings as research content,and develops a series of slim hole separate injection technology strings with different functions according to different well conditions.Through the design of the overall structure scheme of the string,the design and verification of key parts,the optimization of rubber cylinder materials,the laboratory test and the prototype trial production and improvement,the tightness of slim hole string is ensured under the strict conditions of meeting the technical parameters of tool inner and outer diameter,and then small-diameter packer and small-diameter water distributor for well washing are designed,which are verified step by step through continuous tests improved optimization to determine the reliability of design tools.In this paper,the matching test technology in separate layer water injection technology of slim hole is also preliminarily explored,and the overall scheme of matching test technology for slim hole water injection is formulated.Finally,the feasibility of various slim hole separate injection technology string in normal production environment is evaluated through the specific application effect in the field test well.The small diameter separate layer water injection technology string studied in this paper directly overcomes the technical bottleneck of separate layer water injection in small casing wells,realizes effective multi-stage separate layer water injection with reliable sealing,plays a positive role in extending oil well production cycle and increasing crude oil production,enriches and expands the wellbore conditions of separate layer water injection,and meets the requirements of low oil price The trend of low-cost development in oil region has great market application value.