Wenhua Xu^1,3, Yuming Zhu², Yingrong Wei², Ya Su², Yan Xu^1,3, Hui Ji¹, Dehua Liu^1,3,*

Energy Engineering, Vol.120, No.7, pp. 1701-1715, 2023, DOI:10.32604/ee.2023.027703

Abstract Drilling costs of ultra-deep well is the significant part of development investment, and accurate prediction of drilling costs plays an important role in reasonable budgeting and overall control of development cost. In order to improve the prediction accuracy of ultra-deep well drilling costs, the item and the dominant factors of drilling costs in Tarim oilfield are analyzed. Then, those factors of drilling costs are separated into categorical variables and numerous variables. Finally, a BP neural network model with drilling costs as the output is established, and hyper-parameters (initial weights and bias) of the BP neural network is optimized by genetic… More >

Zubing Tang^*

FDMP-Fluid Dynamics & Materials Processing, Vol.19, No.8, pp. 2161-2170, 2023, DOI:10.32604/fdmp.2023.026608

Abstract The mechanical behavior of the test string in deep wells is generally relatively complex as a result of the high temperature and high pressure, severe dogleg and buckling effects, which in some circumstances can even lead to string failure. Traditional computational methods for the analysis of these behaviors are often inaccurate. For this reason, here a more accurate mechanical model of the test string is introduced by considering variables such as temperature, pressure, wellbore trajectory, and buckling, as well as combining them with the deformation and string constraint conditions brought in by changes in temperature and pressure during the tripping,… More >

Yanxian Wu¹, Shouming Zhong¹, Zhigang Guan¹, Lin Song¹, Kun Li², Jiarui Sun², Yuqiang Xu^2,*, Maochuan Tu³, Chaobin Fan³, Jinbin Yang⁴

FDMP-Fluid Dynamics & Materials Processing, Vol.19, No.1, pp. 261-271, 2023, DOI:10.32604/fdmp.2023.020076

Abstract A three-dimensional model for the numerical simulation of casing-cement behavior is used to investigate residual strength in the perforated casing of ultra deep wells. The influence of the hole diameter, hole density and phase angle on the residual strength of the casing under non-uniform stress and fracturing conditions is revealed through the consideration of different perforation parameters. It is shown that the residual strength of the casing increases with the hole diameter and periodically changes with the hole density; the phase angle is the main factor that affects the residual strength of the perforated casing, and the perforation should be… More >

Jingpeng Wang¹, Wei Zhang¹, Zhiwei Lin¹, Lin Song¹, Shiyuan Xie¹, Qi Liu², Wei Wang², Tao Yang², Kai Xu², Meng Li², Yuqiang Xu^3,*

FDMP-Fluid Dynamics & Materials Processing, Vol.19, No.1, pp. 105-116, 2023, DOI:10.32604/fdmp.2023.020049

Abstract An uncertainty analysis method is proposed for the assessment of the residual strength of a casing subjected to wear and non-uniform load in a deep well. The influence of casing residual stress, out-of-roundness and non-uniform load is considered. The distribution of multi-source parameters related to the residual anti extrusion strength and residual anti internal pressure strength of the casing after wear are determined using the probability theory. Considering the technical casing of X101 well in Xinjiang Oilfield as an example, it is shown that the randomness of casing wear depth, formation elastic modulus and formation Poisson’s ratio are the main… More >

Meng Li¹, Kanhua Su¹, Zijian Li², Dongjie Li³, Lifu Wan¹

CMES-Computer Modeling in Engineering & Sciences, Vol.113, No.4, pp. 475-495, 2017, DOI:10.3970/cmes.2017.113.475

Abstract With the consideration of the randomness of complex geologic parameters for ultra-deep wells, an uncertainty analysis method is presented for the extrusion load on casing in ultra-deep wells through complex formation at a certain confidence level. Based on the extrusion load model for casing in ultra-deep wells and the prerequisite of integrity of formation-cement ring-casing, the probability and statistics theory is introduced and the sensitivity analysis on the uncertainty of extrusion load on casing is conducted. The distribution types of each formation parameters are determined statistically. The distribution type and distribution function of the extrusion load on casing are derived.… More >