scholarly journals Modelling of Formation Pore Pressure Inversion during Tight Reservoir Drilling

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
Xiaohui Sun ◽  
Youqiang Liao ◽  
Zhiyuan Wang ◽  
XinXin Zhao ◽  
Baojiang Sun
Keyword(s):  
Pore Pressure ◽  
Early Stage ◽  
Computation Method ◽  
Good Convergence ◽  
Gas Kick ◽  
Tight Reservoir ◽  
Convergence Performance ◽  
Formation Pore Pressure ◽  
Gas Volume ◽  
Robust To Noise

Identifying and controlling a kicking well hinge on quickly obtaining reliable and accurate formation pore pressure. In this study, we derive an analytical model for estimating formation pore pressure when a gas kick occurs during tight reservoir drilling. The model considers the variations in gas volume and pressures in the annulus affected by mutual coupling between the wellbore and formation, as well as bubble migration and expansion in the annulus. Additionally, a numerical computation method that reduces the effect of measurement noise using the Hooke-Jeeves algorithm is proposed. The method is capable of estimating pore pressure during the early stage of a kick in real time, is robust to the inherit noise of the measurements, and can be applied in scenarios when a well shut-in process cannot be performed. The simulation results demonstrate that both kick simulation and formation pore pressure inversion can be conducted via the proposed methodology. The errors of the pore pressure estimating results are less than 2.03% compared to the field data of seven wells. The method is tested and validated to be robust to noise and maintain good convergence performance, thereby providing drilling engineers with a simple and quick way to estimate pore pressure during a kick.

Predicting Formation Pore-Pressure from Well-Log Data with Hybrid Machine-Learning Optimization Algorithms

2021 ◽  
Author(s):  
Mohammad Farsi ◽  
Nima Mohamadian ◽  
Hamzeh Ghorbani ◽  
David A. Wood ◽  
Shadfar Davoodi ◽  
...  
Keyword(s):  
Machine Learning ◽  
Pore Pressure ◽  
Optimization Algorithms ◽  
Well Log ◽  
Log Data ◽  
Hybrid Machine ◽  
Formation Pore Pressure

scholarly journals Study on the combined threshold for gully-type debris flow early warning

2019 ◽  
Vol 19 (1) ◽  
pp. 41-51 ◽  
Author(s):  
Jian Huang ◽  
Theodoor Wouterus Johannes van Asch ◽  
Changming Wang ◽  
Qiao Li
Keyword(s):  
Debris Flow ◽  
Pore Pressure ◽  
Early Warning ◽  
Early Stage ◽  
Warning System ◽  
Early Warning Systems ◽  
Great Loss ◽  
Mountainous Regions ◽  
Pressure Threshold

Abstract. Gully-type debris flow induced by high-intensity and short-duration rainfall frequently causes great loss of properties and causalities in mountainous regions of southwest China. In order to reduce the risk by geohazards, early warning systems have been provided. A triggering index can be detected in an early stage by the monitoring of rainfall and the changes in physical properties of the deposited materials along debris flow channels. Based on the method of critical pore pressure for slope stability analysis, this study presents critical pore pressure threshold in combination with rainfall factors for gully-type debris flow early warning. The Wenjia gully, which contains an enormous amount of loose material, was selected as a case study to reveal the relationship between the rainfall and pore pressure by field monitoring data. A three-level early warning system (zero, attention, and warning) is adopted and the corresponding judgement conditions are defined in real time. Based on this threshold, there are several rainfall events in recent years have been validated in Wenjia gully, which prove that such a combined threshold may be a reliable approach for the early warning of gully-type debris flow to safeguard the population in the mountainous areas.

Evaluation of formation pore pressure behind the casing using borehole gravity data

2016 ◽  
Vol 61 (1) ◽  
pp. 69-92
Author(s):  
Yuliy A. Dashevsky ◽  
Semen Petrov ◽  
Alexandr N. Vasilevskiy ◽  
Oleg B. Bocharov ◽  
Gleb V. Dyatlov
Keyword(s):  
Pore Pressure ◽  
Gravity Data ◽  
Formation Pore Pressure

The Use of LWD Data for the Prediction and Determination of Formation Pore Pressure

2009 ◽  
Author(s):  
Jeremy A. Greenwood ◽  
Michael Raymond Dautel ◽  
Richard Buchanan Russell
Keyword(s):  
Pore Pressure ◽  
Formation Pore Pressure

scholarly journals Transient response of near-wellbore supercharging during filter cake growth

2021 ◽  
Vol 76 ◽  
pp. 46
Author(s):  
Tianshou Ma ◽  
Nian Peng ◽  
Ping Chen ◽  
Yang Liu
Keyword(s):  
Pore Pressure ◽  
Filter Cake ◽  
Early Stage ◽  
Drilling Fluid ◽  
Reduction Rate ◽  
Time Dependent ◽  
Low Permeability ◽  
Drilling Fluids ◽  
Dynamic Filter ◽  
Cake Porosity

Supercharging in the vicinity of a borehole is an important factor that affects formation damage and drilling safety, and the filter cake growth process has a significant impact on supercharging in the vicinity of the borehole. However, existing models that predict pore pressure distribution overlook dynamic filter cake growth. Thus, an analytical supercharging model was developed that considers time-dependent filter cake effects, and this model was verified using a two-dimensional numerical model. The influences of filter cake, formation, and filtrate properties on supercharging were investigated systematically. The results indicate that time-dependent filter cake effects have significant influence on supercharging. Supercharging increases in the early stage but decreases over time because of the dynamic growth of filter cake, and the supercharging magnitude decreases along the radial direction. Because of filter cake growth, the magnitude of supercharging falls quickly across the filter cake, and the decreased magnitude of pore pressure caused by the filter cake increases. Supercharging in low-permeability formations is more obvious and the faster rate of filter cake growth, a lower filtrate viscosity and faster reduction rate of filter cake permeability can help to weaken supercharging. The order of importance of influencing factors on supercharging is overbalance pressure > formation permeability > formation porosity ≈ filtrate viscosity > filter cake permeability attenuation coefficient > initial filter cake permeability control ratio > filter cake growth coefficient > filter cake porosity. To alleviate supercharging in the vicinity of the borehole, adopting drilling fluids that allow a filter cake to form quickly, optimizing drilling fluid with a lower filtrate viscosity, keeping a smaller overbalance pressure, and precise operation at the rig site are suggested for low-permeability formations during drilling.

scholarly journals Post Drill Pore Pressure Prediction for Geo-hazard Assessment of Offset Wells in Hamoru Field

2020 ◽  
Vol 17 (2) ◽  
pp. 97-103
Author(s):  
A. Ogbamikhumi ◽  
O.M. Hamid-Osazuwa ◽  
E.A. Imoru
Keyword(s):  
Pore Pressure ◽  
Hazard Assessment ◽  
Seismic Data ◽  
Field Analysis ◽  
Well Logs ◽  
Formation Pressure ◽  
Pore Pressure Prediction ◽  
Pressure Regime ◽  
Formation Pore Pressure ◽  
Subsurface Formation

Understanding the distribution and variation of subsurface formation pressure is key to preventing geo-hazards associated with drilling activities such as kicks and blow out. To assess and prevent such risk in drilling offset wells in the Hamoru field, prediction of pore pressure was done to understand the pressure regime of the field using well logs in the absence of seismic data. Two commonly used methods for formation pressure prediction; Bower’s and Eaton’s methods were adopted to predict pore pressure and determine the better of the two methods that will be more suitable for the field. The cross-plot of Vp against density disclosed that compaction disequilibrium is the prevalent overpressure mechanism. The prediction of Pore pressure with Eaton’s method gave results comparable to the acquired pressure in the field, typical of what is expected when compaction disequilibrium is the dominant overpressure mechanism. Since the result of Bower’s method over estimated formation pressure, Eaton’s method appears to be the better choice for predicting the formation pore pressure in the field. Analysis of the predicted pore pressure reveals the onset of overpressure at depth of 2.44 km. The formation pressure gradient ranges from 10.4 kPa/m to 15.2 kPa/m interpreted as mild to moderately over pressure. Keywords: Geohazard, over-pressure, Eaton’s method, Bower’s method, normal compaction trend

scholarly journals Division Method and Seepage Law of Seepage Channels in a Tight Reservoir

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-18
Author(s):  
Zhenkai Wu ◽  
Feifei Fang ◽  
Xizhe Li ◽  
Hanmin Xiao ◽  
Xuewei Liu ◽  
...  
Keyword(s):  
Two Phase Flow ◽  
Early Stage ◽  
Stress Sensitivity ◽  
Phase Flow ◽  
Threshold Pressure ◽  
Two Phase ◽  
Threshold Pressure Gradient ◽  
Tight Reservoir ◽  
Oil Water ◽  
Seepage Law

Tight oil reservoirs are characterized by a low porosity, low permeability, and strong heterogeneity. The macropores, throats, and microcracks in reservoirs are the main seepage channels, which affect the seepage law in the reservoirs. In particular, oil-water two-phase flow in different types of pores requires further study. In this study, two groups of online NMR displacement experiments were designed to study the seepage characteristics of tight oil reservoirs. It was found that the main seepage channels for oil-water two-phase flow are the microcracks, large pores, and throats in the reservoir. The large pores are mainly micron and submicron scale in size. The oil in the small pores is only transferred to the large pores through imbibition to participate in the flow, and there is no two-phase flow. Based on the influence of different pore structures on the seepage law of a tight reservoir, the pores were divided into seepage zones, and a multistage seepage model for tight reservoirs was established. Based on this model, the effects of the imbibition, stress sensitivity, threshold pressure gradient, and Jamin effect on model’s yield were studied. The results show that imbibition is no longer effective after a while. Owing to the stress sensitivity, the threshold pressure gradient, and the Jamin effect, oil production will be reduced. As the parameter value increases, the oil production decreases. The production decreases rapidly in the early stage of mining while decreases slowly in the later stage, exhibiting a trend of high yield in the early stage and stable yield in the later stage.

Two-Dimensional Pore Pressure Distribution Model to Evaluate Effects of Shale Semipermeable Membrane Characteristics

2019 ◽  
Vol 142 (1) ◽  
Author(s):  
Jia Wei ◽  
Yuanfang Cheng ◽  
Chuanliang Yan
Keyword(s):  
Diffusion Coefficient ◽  
Pressure Distribution ◽  
Pore Pressure ◽  
Effective Diffusion Coefficient ◽  
Early Stage ◽  
Drilling Fluid ◽  
Effective Diffusion ◽  
Solute Diffusion ◽  
Sensitivity Analyses ◽  
Distribution Model

During the drilling of shale formations, drilling fluids can intrude into the wellbore, raise the pore pressure, and lead to wellbore instability. Based on the thermodynamic theory, a new model was established to calculate pore pressure. The model considers the effects of solute diffusion and solution convection and conducts sensitivity analyses. The results show that the drilling fluid activity significantly affects the pore pressure distribution. The pore pressure under high drilling fluid activity will increase rapidly in the early stage. Low drilling fluid activity can effectively suppress the growth of pore pressure. And a low effective diffusion coefficient of solute and a high membrane efficiency also help to reduce pore pressure. Therefore, reducing drilling fluid activity should be conducted in priority in drilling fluid design. Lowering its solute effective diffusion coefficient and increasing its viscosity can also be considered as auxiliary methods.

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