The Rwd With Drilling To Expand Now The Ministry Of Bha Design And Mechanical Behavior

The reaming while drilling (RWD) is one technology that the drilling and reaming works are finished at the same time without drilling a hole before the reamer been put downhole to ream the borehole, it cuts the drilling cost. The RWD tool is made of a pilot bit, a pilot stable pad, a pilot-hole blade, and reaming blades. It's segmental design offers more alterability for the BHA and the pilot bit choices, meeting requests of most specifically trajectories strictly control, and It has the following characteristics: the simple tool structure, without active parts, the stable and regular reaming size, etc. The RWD is an effective means to solve sticking in complex deep wells, apply the un-conventional well profile and improve cementing quality. The technology is in control of overseas technique service company, providing technique service only. The data of tools development and BHA design principle were not published. Recently, the type of tool developments and fields experimentation were taken in our country. It is very important to quicken domestic RWD technology development and application, research on RWD BHA design and mechanics analysis, adapting the deep and ultra-deep wells development. In the paper, systematic researches of RWD BHA design and it's mechanics characteristics, dynamical behavior and reaming rock- breaking mechanism were made to uncover the RWD system's mechanics laws, provided theory foundation to enhance RWD technology application level.Considering the geometric non-linear questions of BHA force and it's deformation, the elastic mechanics analysis theories and methods of the little-strain & large -deformation were to adopted in the paper to study the load and deformation of RWD BHA. At the same time, after considering RWD tool's torsion , a three-dimension finite element analysis model was established. The BHA deformations and strength characteristics can be simulated by the model more really. The lateral force and the rotary angle on the bit (pilot hole bit, reamer) are main performance indexes to RWD BHA mechanics performances, and synthesizing the effects of deformations and mechanics behaviors of the bit, the stabilizers, the reamer, the contact point between the drilling string and borehole . So a clear mechanics index was put forward to confirm RWD BHA mechanics characteristics and evaluate analyze RWD behavior. Some typical RWD BHA designs and mechanics characteristics analysis were taken The BHAincludes : 1) RWD BHA without the stabilizer;2). RWD BHA with a single stabilized). RWD BHA with two stabilizers; 4). RWD BHA with three stabilizers. These researching achievements offer some scientific theories foundations for the RWD BHA optimization designs and it's construction.Three-dimension drilling stem strength analysis based on considering the torsion load and studies deformation, bend-moment, stress, the distribution characteristics of RWD BHA was made . The tangential load of the RWD string, i.e. the torsion load, does a striking effect on its deformation and strength. So RWD string's strength should be fully attached importance to in optimization RWD designs and in the actual construction works.Considering the load of RWD BHA actually in the borehole, a three-dimension finite element simulation of RWD torsion vibration was finished.. In the meantime; a mechanics analysis model is established which embodies the effecting factors as the reamer's quality eccentricity, the top rig's support, etc. Some discussion such as the RWD BHA's torsion vibration frequency, its dynamic characteristics was done. At last, a technology methods is offered to avoid the dangers bring about by the torsion vibration.In the course of reaming, the rock mechanics' coupling analysis between the reamer and the rock is very important for studying rock- breaking mechanism. The elastic-plastic finite element mechanics analysis models were established, by using the numerical analysis principles and methods, reamer rock-breaking mechanism simulations was done applying the Mohre-Kulun strength rule, then the studies on...