Wenchang Wang

Prediction of Burst Pressure of Pipes With Geometric Eccentricity

The number of papers submitted to the JPVT has increased significantly this year. By the end of this third quarter, the total number of submitted papers exceeded the average number for the past years. This is a good sign for the health of the journal. The JPVT is unique in some aspects. The contents of the papers are diverse including basic science, applied science, and practical engineering solutions to systems being operated in PVP industries. Many of the papers have been used for developing ASME Codes and Standards. As a result, there is a good mixture of authorships from Academies, Industries, and Government Agencies. Two special issues have progressed well so far. One is a special issue for the Golden Anniversary of Pressure Vessels and Piping Division (PVPD), and the other is a special issue for Application of Composite Materials to PVP Technology. If you have any suggestions or comments to improve the journal in every aspect, please feel free to provide me with your input.

Lateral vibration analysis of pre-bent pendulum bottom hole assembly used in air drilling

In the air drilling process, the pre-bent pendulum bottom hole assembly (PBP-BHA) has excellent performance in controlling the well deviation and improving the wellbore quality, but the mechanism that is closely related to the dynamics of the PBP-BHA has not been ascertained. In this paper, an effective technique combining the weighted residuals method with the finite element method is presented to study the PBP-BHA lateral vibration. First, a three-dimensional nonlinear static model of pre-bent BHA is established under small deformation condition and solved by the weighted residuals method and optimization method, so as to define the tangent point according to the deformation characteristics of the PBP-BHA. This tangent point determines the end of the effective PBP-BHA length that starts from the drill bit. Subsequently, the finite element model of PBP-BHA is established to solve the lateral natural frequencies and mode shapes of the PBP-BHA. After considering the borehole wall constraint, the modal superposition technique is used to obtain the steady dynamic responses of the PBP-BHA. Meanwhile, the dynamic performance of the PBP-BHA used in the actual air drilling process is calculated to obtain its critical speeds and working status chart. The critical speeds of the PBP-BHA are 80 r/min and 190 r/min, which are far away from the surface rotary speed in the actual drilling site. Through comparing with the dynamic characteristics of regular BHA with the same structural parameters, it is discovered that the bend angle in the PBP-BHA plays a crucial role in improving the dynamic performance of the PBP-BHA. Moreover, the technique presented in this study can be used to make a reasonable design of BHA configuration and optimize drilling parameters.

The Determination of Ultimate Releasable Hook Load in Casing Running Through an Air-filled Wellbore

The pipe is frequently stuck in casing running through the wellbore drilled by air hammer, and releasing part of suspending weight is commonly practiced to solve this problem, which would engender the strong axial vibration of casing string and make the operation in high risk when wellbore is filled with air or gas. In this paper, the propagation mode of the stress wave has been distinguished based on explicit dynamic finite analysis, where various length of string and released load have been considered. The influence of damping to the fluctuation characteristics of hook load has been discussed, and Rayleigh damping has been applied. With the investigation of the stress wave characteristics in the vibration of casing string, a new method to determine the ultimate releasable hook load in casing running through an air-filled wellbore has been proposed. The results have been validated in an oilfield of western China. The methodology and approach presented in this paper can be used to guide operation in casing running practices by engineers.