Abstract:With regard to the challenges of high friction， drag force， etc. during drilling directional and horizontal wells， ??127 hydraulic oscillation friction reduction tool was developed， which is able to effectively reduce the friction force between the drill string and the wellbore or inner wall of casing， improve weight on bit transfer， extend the length of directional and horizontal sections， and increase the rate of penetration. The mechanism of hydraulic oscillation antifriction drilling technology is introduced. The main parts of the tool are analyzed， and the operating principle is studied. The feasibility and the vibration stability of the tool were verified by numerical simulation， laboratory test and field test. The results showed that the performance of the device was reliable， and the hydraulic pulse frequency， pressure fluctuation amplitude and axial vibration displacement increased with flow rates. The results can provide references for research and development of related drilling tools and technologies for friction reduction， ROP improvement， etc.

Abstract:The difficulty in casing running needs to be solved urgently for extended reach wells in Bohai Oilfield. Taking a well A in Bohai Oilfield as an example, this paper analyzes the technical difficulties in φ244.5mm casing running from the design point of view, and analyzes the factors affecting casing running using the software of LANDMARK. The results show that if the kick off point becomes shallow, the surface casing running depth becomes deeper, and the hold angle is over large, then less casing unit weight, reduction in the friction coefficient, and increase in the floating section will lead to reduction in casing running friction, and increase in the casing hanging weight. By optimizing the above parameters, the φ244.5mm casing running plan was designed with the floating manner with the length of the floating section as 1200m. The relative error between the predicted value and the measured value of the casing hanging weight was 6.34%, which was within the allowable engineering error range. The casing running design process has been developed for extended reach wells in Bohai Oilfield. In the casing running design, the kick off point, the surface casing running depth, the case weight, the friction coefficient and the floating section should be considered comprehensively to optimize the running plan to ensure successful casing running.

Abstract:Torque and drag are major problems in extended reach well drilling, which restrict the effective well trajectory extension, especially in the application of conventional drilling and completion technologies. In Jidong oilfield, based on the conventional drilling and completion technologies, by the detailed study and optimization of well trajectory design, BHA optimization, accurate prediction and control of the torque and drag and the comprehensive evaluation of extension limit in recent years, the stimulation analysis and verification are made on the wellbore mechanical behavior of middle-deep extended well in Nanpu beach area, the feasibility knowledge of extended well drilling practice is enhanced to guide the design of drilling and completion program. Dozens of extended wells with horizontal displacement more than 3000m have been constructed in Nanpu beach, the maximum horizontal displacement reaches 4940m, which provides technical support for the extended reach well drilling of Nanpu beach under the conventional economic and technological conditions.

Abstract:Well Hasheng-X1 is an important risk wildcat in Shengli oilfield, which is a directional well with double targets with high deviation angle, long steady inclined section and large horizontal displacement. As a risk wildcat, there is less drilling data of adjacent wells and there are uncertain factors of formation lithology, formation pressure and layer section variety. It is an important basis to ensure smooth construction to determine reasonable casing program, optimized trajectory, good mud performance parameters and other relevant technical measures. Based on the detail analysis on the very few information, the optimized schemes and technical measures were proposed in well trajectory design, casing program design, bottom hole assembly & drilling method selection, drilling fluid design and cementing design; these above could be the technical support and theoretical basis to the design of the risk wildcat in Shengli oilfield.

Abstract:The design constrained equations of azimuth drift is a nonlinear one that contains 3 independent and several hidden unknowns, the numerical iteration method should be used to get the numerical solution. The vertical depth increasing equation was provided, by using vertical depth increasing equation of the constrained equations, one of the 3 independent unknowns was expressed as functions of the other 2 unknowns, which were used for dimension reduction of the design constraint equations. The paper analyzed the calculation details of hidden unknowns and gave the recursive algorithm for hidden unknowns. The numerical value arithmetic of constrained equations after dimension reduction was also put forward, that was half- shrinkage grid method, which could be applied to quickly and reliably find the numerical solutions of design, especially for programming computer software.

Abstract:Friction and torque are main factors that hinder extending of long horizontal section well. Optimization of well trajectory is one way to reduce friction and torque. Friction and torque of various well profiles with different build-up rate and different displacement before target are calculated, and the influence of friction coefficient on various well profiles is analyzed. The results show that low build-up rate and simple trajectory are suitable for extended reach horizontal well with long horizontal section.

Abstract:Catenary shape profile is a classical type of extended reach well; a nonlinear equation with the initial well oblique angle as unknown factor should be solved for its design. As this unknown factor exists in several triangular functions and logarithmic functions, large amount of calculation is required; and commonused interative solution method is not so ideal. The nonlinear equation is changed to a new one only with logarithmic function and polynomial function, to which geometric analysis is made on the function character, and step search algorithm and adaptive step search algorithm are proposed for solution interval. Numerical solution of new equation can be got rapidly in solution interval by dichotomy. The effectiveness of the above algorithm was proved by the design case of extended reach well, and relationship between hole curvature in arc well section and equation solution was discussed. The algorithm introduced in this paper can be applied in the development of computer software for the design on extended reach well trajectory.

Abstract:The trajectory of cycloid extended reach well consists of straight section-arc section-cycloid section-steady inclined section with the minimum or very small friction and friction moment. The design comes down to solution for system of two elements equations, when the unknown design parameters are according to the initial well deviation angle of cycloid section or deviation angle of remained inclined section, the equations are nonlinear without analytical solution. The equivalent triangle function equation is obtained by mathematical transformation and simplification; numerical iterative algorithm for triangle function equation approximate solution is put forward by interval query and bisection method. The numerical examples show the algorithm has high calculation accuracy and quick operation with good iterative stability. This new algorithm can be applied in the development of computer software to improve the applicability.