Research On The Nonlinear Vibration Characteristics Of The Reaming While Drilling System In The Horizontal Sectio

With the deterioration of the quality of oil and gas resources,the exploration and development of oil and gas resources will go deep.Horizontal wells play an important role in increasing production of reserves,therefore,the drilling technology of deep horizontal wells will be more widely used and developed in the future.However,due to the small annular space gap and thin cement sheath in deep wells,accidents such as formation pressure leakage,hole shrinkage,sticking and casing collapse often occur.With the improvement of HEWD technology,the above problems can be solved.The synchronization of drilling and reaming can be achieved by connecting reamer to conventional BHA.But reamer is easy to cause severe vibration of bottom hole assembly(BHA),leading to wear and tear of reamer blade,which seriouslys restrict the exploitation of deep oil and gas resources.In order to reveal the mechanical characteristics of HEWD’s BHA in horizontal well,decrease the vibration of the reamer,and increase the rate of penetration and the quality of the hole,this dissertation based on drill string dynamics,elastoplastic mechanics and rock mechanics,used numerical calculation method and studied the axial,transverse and torsional vibration characteristics of the HEWD’s BHA in horizontal well,and the influence of BHA and drilling parameters on its vibration characteristics.The main contents of this dissertation are summarized as follows:(1)The contents and methods of this dissertation are determined by extensive investigation of the development of HEWD technology and its related dynamics.(2)The numerical model of HEWD system in horizontal well is established based on actual drilling process and conditions.The coupling effects of the interaction between bit/reamer and rock,the interaction among three cutting structures,and the contact between drill string and borehole wall are considered comprehensively.Finally,the reliability of the model is verified by comparing the simulation and actual drilling results under the same working conditions and assembly of drilling tools.(3)In order to find out which of the axial,transverse and torsional vibration is the main factors leading to the failure of reamer,this dissertation studied the vibration characteristics of HEWD in horizontal well,and also compares and analyses the differences of vibration characteristics between single and double reamer while drilling under the same weight and rotary.(4)Regard the distance between the bit and the main reamer,the position of the stabilizer and the drilling parameters as the research object,this dissertation analyzed the influence of these factors on the vibration intensity,rate of penetrate and well track of the HEWD system in horizontal wellThe results of this dissertation gives a theoretical support of application of HEWD technology in horizontal well section,and provides theoretical guidance for the design of HEWD’s BHA and the selection of drilling parameters.