The Research Of Technology On Bottom Extension With Coiled Tubing

Arised in the international oil industry in the late 20 th century,Coiled tubing drilling technology is a very popular new drilling technology.This new drilling technology uses a continuous length of tubing to replace the conventional drill pipe,and cooperate with the downhole drilling tools for bottom extension.This technique does not require stopping the pump and make a connection in the drilling process,and can achieve the continuous circulation of the drilling fluid,improve the speed of tripping and job security,reduce the drilling time and drilling cycle.The old oil fields,by using the CTD technical to reentrant deepen or sidetrack,not only can save the cost of drilling,but also can be found and develop the new reserves,contribute to the stable output of old oil fields,enhance oil recovery and increase oilfield efficiency.At the same time,CTD technology is conductive to the implementation of slimhole,underbalanced drilling.For low pressure easy leakage layer drilling,can be negative pressure drilling,safe and convenient to improve the success rate of drilling;For water sensitive fragile formation,CTD can use nitrogen drilling,oil-based drilling fluid,drilling and other methods,for coalbed gas and shale gas and other special gas reservoir development to provide a safe and reliable drilling technology.At present,many oilfields in the world has entered the late development,especially in our country most mainland oilfield has entered high water cut stage,production fell sharply,as well as restricted by comprehensive drilling technology and equipment,etc,there are some low permeability reservoirs and special reservoirs is not yet fully developed,and CTD technology is definitely a good way to solve this kind of problem.Combined with the significant professional project of the National Science and Technology(task 6 of project 36)“The coiled tubing equipment and the application of technology” research the process for coiled tubing sidetracking.In view of the coiled tubing bottom hole stretching process were studied.Research results can be used for guiding the scene of the coiled tubing drilling test,And preliminary form adapted to the study of coiled tubing drilling sidetracking technology in China,making a little contribution to the development and improvement of coiled tubing drilling technology.This article are mainly studied from the following aspects:(1)Articles of coiled tubing drilling equipment and tools required for summary,and introduced the important function of equipment and tools and technical parameters in detail.Recommended the bottom hole assembly for drilling extension.Also analyzed the factors that affect the working life of CT,and made detailed instructions of coiled tubing operating characteristics.(2)Using the Energy conservation and the Differential equation method to derived the formula of critical bending coiled tubing.The study found that the coiled tubing occurring sinusoidal buckling critical axial compression was 25.1 KN.(3)Established the physical model of CTD for Jet drilling.Presents a small size bit(Φ118)construction parameters and defined the key parameters.(4)In porous jet,before the hole jet is responsible for the broken rock,the back-ward jet is responsible for generating reverse thrust.After the detailed calculation,we can get that when the backward nozzle diameter is 4mm,the forward nozzle diameter is 3.2mm,and the backward nozzle spray angle is 20 degrees,the forward nozzle spray angle is 30 degrees,as well as the number of nozzles(the backward nozzles and the forward nozzles)are four.So as to produce certain propulsion.(5)Using FLUENT software for flow field simulation.Through calculation combined with software simulation of the nozzle structure and parameter optimization design of bit.In this paper,the level of coiled tubing period of form a complete set of tools and auxiliary of the bit nozzle jet structure parameters for the design,can increase to a certain extent,an extension of the horizontal interval distance.The design scheme as a kind of effective means of technological innovation,the field work will produce certain guiding significance.