Open Access
EDITORIAL
Open Access
ARTICLE
Jun Li1, Shunji Yang1, Boyun Guo1,2, Yin Feng2, Gonghui Liu1,3
CMES-Computer Modeling in Engineering & Sciences, Vol.89, No.2, pp. 79-96, 2012, DOI:10.3970/cmes.2012.089.079
Abstract In the process of gas drilling, the mechanism of transport of the cuttings up the annulus is significant, because it controls the minimum amount of volume of the required gas, the cost of cleaning the borehole, the stability of the borewell and the drill pipe erosion, etc. However, current studies in this area are only limited to theoretical discussions. The reason why drill cuttings are of very fine sizes , in air drilling, is believed to be due to the repeated crushing action of drill bit at the bottom of the hole, and the collision between cuttings themselves and the… More >
Open Access
ARTICLE
Xuejun Hou1,2, Deli Gao1, Zhonghou Shen1
CMES-Computer Modeling in Engineering & Sciences, Vol.89, No.2, pp. 97-110, 2012, DOI:10.3970/cmes.2012.089.097
Abstract Microhole drilling (MHD) is a new frontier drilling technology in which the diameter of wellbore is less than 88.9mm and coiled tubing (CT) is used as drill string. The CT wound around reel for MHD has small bending radius and large length to result in large circulating flow resistance and affect normal MHD circulation. The calculation model for curvature radius and length of CT wound around reel are established by analyzing the relationships among the various geometrical parameters of the reel system. The calculation model is combined with Dean number and power-law fluid state equation to put forward the calculation… More >
Open Access
ARTICLE
Deli Gao1, Zhen Dong1, Hui Zhang1
CMES-Computer Modeling in Engineering & Sciences, Vol.89, No.2, pp. 111-122, 2012, DOI:10.3970/cmes.2012.089.111
Abstract The bottom hole pendulum assembly is a type of bottom hole assembly (BHA) for controlling the hole deviation, and has been widely used in drilling engineering. Generally, the ability of the drill bit to penetrate laterally, is different from its ability to penetrate axially, so that the drill bit has an anisotropy which affects the hole-deviation-control characteristics of the BHA. The tilt angle and the side force of the drill bit are obtained by a BHA analysis based on the method of weighted residuals. Thus, the effective drilling force can be determined using the rock-bit interaction model. On this basis,… More >
Open Access
ARTICLE
Yongsheng An1, Xiaodong Wu1, Deli Gao1
CMES-Computer Modeling in Engineering & Sciences, Vol.89, No.2, pp. 123-142, 2012, DOI:10.3970/cmes.2012.089.123
Abstract The accuracy of numerical simulation of a two-phase (oil and water) flow in a fractured horizontal well depends greatly upon the types of grids used in the computation. Cartesian grids have been widely used in recent years, but they have some disadvantages in describing complex structural wells, such as fractured horizontal wells. For example, Cartesian grids are not efficient in describing the main wellbores and the fractures of fractured horizontal wells, and the results can frequently suffer from grid orientation effects, even though a grid-refinement is often introduced to enhance the adaptability of a Cartesian grid.
The PEBI (Perpendicular Bisector)… More >
Open Access
ARTICLE
Deli Gao1,2, Lianzhong Sun1,3, Hongshu Wei4, Shunwen Wang4
CMES-Computer Modeling in Engineering & Sciences, Vol.89, No.2, pp. 143-162, 2012, DOI:10.3970/cmes.2012.089.143
Abstract Due to the complexity of forces acting on the down-hole tubular strings in extended
reach drilling (ERD), the factors which influence the process should be taken into
account as much as possible, in order to predict the down-hole drag & torque more
accurately. This can help us to identify and prevent the problems related to downhole drag & torque in ERD. The effects of such factors, as the tubular buckling, the
buoyancy, the mechanical resistance and the friction reducer, on down-hole drag &
torque, are taken into account in this paper, in order to improve the accuracy of the
prediction… More >
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