Study on Wellbore Stability of Shallow Sediments in Deepwater Drilling

Zhang, Jun; Ai, Chi; Zeng, Bo; Li, Yuwei; Zeng, Jia

doi:10.2174/1874834101701010048

Cited by 3 publications

(2 citation statements)

References 20 publications

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“…A deep water drilling water pipe system and vibration active control system including a sensor, actuator, signal processing module control module for monitoring longitudinal and lateral vibration of the drain water pipe system. Zhang et al found that although deep-water formations have their own characteristics compared with land and shallow-water formations, it is the same in wellbore stability research methods [6]. Zheng et al studied the influence of water depth on the fracture pressure and found that the fracture pressure of the deepwater wellbore is relatively close to the pressure of the overlying strata, but no specific model [7].…”

Section: Literature Reviewmentioning

confidence: 99%

Prediction and Optimization of Stability Parameters of Borehole Sensor for Deep Water Drilling Based on Genetic Algorithm

Huang¹,

Xia

Cai

et al. 2022

Journal of Sensors

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In order to study the prediction and optimization of borehole stability parameters in deepwater drilling based on genetic algorithm. First, a genetic hybrid algorithm based on pattern search is proposed. Then, based on the adaptive genetic algorithm, the evolutionary population is searched for patterns, which makes the hybrid algorithm not only has a strong global search ability but also improves the local optimization accuracy. Finally, the unit footage cost in the drilling process is taken as the objective function, and the algorithm is verified by taking the drilling in Karamay area as an example. The calculation results show that if the bit wear reaches 0.8-0.9 and then the bit is pulled out, the utilization rate of the bit can be increased, the design efficiency and accuracy can be improved, and the drilling cost can be reduced. The wear amount of the optimized bit is higher than that of the actual bit. Increasing the utilization rate of the bit can reduce the cost of drilling meters to a certain extent and improve the economic benefits of drilling. The objective function and constraint conditions for the optimization of drilling parameters are determined, and the algorithm is verified with the drilling data of Karamay Oilfield. The results show that the algorithm improves the stability and speed of iterative convergence and improves the reliability of data analysis results. Based on the regional three-dimensional formation rock parameter data volume, the optimization method can be used to optimize the drilling parameters before drilling and provide a basis for formulating the drilling design scheme.

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Section: Literature Reviewmentioning

confidence: 99%

Prediction and Optimization of Stability Parameters of Borehole Sensor for Deep Water Drilling Based on Genetic Algorithm

Huang¹,

Xia

Cai

et al. 2022

Journal of Sensors

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“…Based on the air drilling practice in Karamay oilfield, it is put forward that the influencing factors of wellbore stability in air drilling include mechanics and chemistry (Li 1994). The concentration and chemical properties of liquid phase in mist drilling effected on borehole stability were evaluated by laboratory experiments (Huang et al 1995). The von Mises failure criterion is used to get reliable prediction of the collapse pressure (Guo and Ghalambor 2002).…”

Section: Introductionmentioning

confidence: 99%

Analysis on borehole stability of gas drilling with complete stress–strain and thermal stress theory

Zhu

Wang

Xiong³

et al. 2022

Arab J Geosci

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In conventional mud drilling, sufficient drilling fluid density is required to maintain wellbore stability. However, in gas drilling, the support ability of gas in wellbore is very weak, and the wellbore stability is usually good. This shows that the borehole instability mechanism of gas drilling is different from that of mud drilling. In gas drilling, the borehole wall rock still has a certain bearing capacity after reaching the peak strength. In this paper, the stability of gas drilling wellbore is studied by using the complete stress–strain model. The deformation of rock around borehole in gas drilling can be divided into elastic zone, plastic zone, and broken zone. The radii of plastic zone and broken zone were used to evaluate the stability of borehole wall. This method has a good general applicability to the case of no thermal stress in borehole wall rock. However, due to throttling and cooling as gas flows out of the bit nozzle during gas drilling, thermal stress occurs when the cryogenic flow in the annulus meets the hot formation. Therefore, thermal stress is introduced into the complete stress–strain calculation model. The radii of plastic zone and broken zone are calculated according to the actual drilling data, and compared with the measured borehole diameter. The results show that the model is reasonable and effective. Analysis shows that in gas drilling process, the borehole temperature is much lower than the original formation temperature near the bottom of the borehole, and the borehole temperature is higher than the formation temperature in the upper part of the borehole. Thermal stress has a significant effect on borehole stability. The thermal stress in the bottom borehole makes the rock shrink and offset the expansion of the original in situ stress on the surrounding rock, thus enhancing the stability of the borehole wall. The surrounding rock in the top borehole expands under the action of thermal stress, enhancing the expansion of the surrounding rock toward the borehole and aggravating the instability of the borehole wall. The model can be used to better explain the wellbore instability mechanism of gas drilling, and it is more intuitive to use plastic zone radius and broken zone to characterize wellbore stability of gas drilling.

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A Novel Method for Fracture Pressure Prediction in Shallow Formation During Deep-Water Drilling

Yang

Liu²,

Wang

et al. 2021

Journal of Energy Resources Technology

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A large numbers of deep-water drilling practices have shown that more than 60% of deep-water wells have the complex leak-off during the drilling process, which poses great difficulties and challenges for the safety and operation time of deep-water drilling. The purpose of this article is to establish a method for predicting the fracture pressure in shallow formations. In this study, the deep-water shallow formation was divided into the upper unconsolidated soil layer and the lower diagenetic rock layer according to the geotechnical distribution characteristics of the deep-water shallow formation. The location of the transition soil/rock layer zone was determined using the upper soil layer density trend line and the lower rock layer density log data regression trend line. The deep-water shallow fracture pressure prediction model was established based the soil/rock transition zone. Shear failure criterion was used above the transition zone and tensile failure criterion is used below the transition zone. The shallow fracture pressure of 6 drilled exploratory wells in the X block from the South China Sea were calculated using this new method and the calculation errors were all less than 3.18%. Moreover, the shallow fracture pressure body in this block was established using the Kriging interpolation method based on 6 drilled exploratory wells data. This shallow fracture pressure body established here were used to predict 9 development wells shallow fracture pressure with a predictive error less than 1.7% and there were no drilling accidents. The case study demonstrates that the new model can significantly improve the prediction accuracy, has good prospects for popularization and application.

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Study on Wellbore Stability of Shallow Sediments in Deepwater Drilling

Cited by 3 publications

References 20 publications

Prediction and Optimization of Stability Parameters of Borehole Sensor for Deep Water Drilling Based on Genetic Algorithm

Prediction and Optimization of Stability Parameters of Borehole Sensor for Deep Water Drilling Based on Genetic Algorithm

Analysis on borehole stability of gas drilling with complete stress–strain and thermal stress theory

A Novel Method for Fracture Pressure Prediction in Shallow Formation During Deep-Water Drilling

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