Experimental Investigation on Wellbore Strengthening Based on a Hydraulic Fracturing Apparatus

2017 ◽  
Vol 140 (5) ◽  
Author(s):  
Cheng Cao ◽  
Xiaolin Pu ◽  
Zhengguo Zhao ◽  
Gui Wang ◽  
Hui Du
Keyword(s):  
Plastic Deformation ◽  
Hydraulic Fracturing ◽  
Development Stage ◽  
Pressure Curve ◽  
Lost Circulation ◽  
Fracture Pressure ◽  
Instability Development ◽  
Fracturing Process ◽  
Crack Stability ◽  
Wellbore Strengthening

Lost circulation is a serious problem which always exists in the petroleum industry. Wellbore strengthening by lost circulation materials (LCMs) is a commonly applied method for mitigating lost circulation. This paper presents a hydraulic fracturing apparatus to investigate the effect of material type, concentration, and particle size distribution (PSD) of LCMs on wellbore strengthening behavior. In addition, the characteristics of pressure curves in the fracturing process are analyzed in detail. The results showed that the fracture pressure of the artificial core can be increased by LCMs, and there exists an optimum concentration of LCMs for the maximum wellbore strengthening effect. The LCMs with wide PSD can significantly increase the fracture pressure. However, some LCMs cannot increase or even decrease the fracture pressure; this is resulting from the LCMs with relatively single PSD that makes the quality of mud cake worse. The representative pressure curve in the fracturing process by drilling fluids with LCMs was divided into five parts: the initial cake formation stage, elastic plastic deformation stage, crack stability development stage, crack instability development stage, and unstable plugging stage. The actual fracturing curves were divided into four typical types due to missing of some stages compared with the representative pressure curve. In order to strengthen the wellbore in effective, good LCMs should be chosen to improve the maximum pressure in the elastic plastic deformation stage, extend the stable time of pressure bearing in the crack stability development stage, and control the crack instability development stage.

scholarly journals Laboratory Study on Core Fracturing Simulations for Wellbore Strengthening

Geofluids ◽  
2019 ◽  
Vol 2019 ◽  
pp. 1-18 ◽  
Author(s):  
Biao Ma ◽  
Xiaolin Pu ◽  
Zhengguo Zhao ◽  
Hao Wang ◽  
Wenxin Dong
Keyword(s):  
Bearing Capacity ◽  
Laboratory Study ◽  
Drilling Fluid ◽  
Drilling Fluids ◽  
Lost Circulation ◽  
The Core ◽  
Fracture Pressure ◽  
Fluid Systems ◽  
Fracturing Process ◽  
Wellbore Strengthening

The lost circulation in a formation is one of the most complicated problems that have existed in drilling engineering for a long time. The key to solving the loss of drilling fluid circulation is to improve the pressure-bearing capacity of the formation. The tendency is to improve the formation pressure-bearing capacity with drilling fluid technology for strengthening the wellbore, either to the low fracture pressure of the formation or to that of the naturally fractured formation. Therefore, a laboratory study focused on core fracturing simulations for the strengthening of wellbores was conducted with self-developed fracture experiment equipment. Experiments were performed to determine the effect of the gradation of plugging materials, kinds of plugging materials, and drilling fluid systems. The results showed that fracture pressure in the presence of drilling fluid was significantly higher than that in the presence of water. The kinds and gradation of drilling fluids had obvious effects on the core fracturing process. In addition, different drilling fluid systems had different effects on the core fracture process. In the same case, the core fracture pressure in the presence of oil-based drilling fluid was less than that in the presence of water-based drilling fluid.

scholarly journals The Calculation Model of Initiation Pressure During Hydraulic Fracturing Process of Perforated Coal Seams

2013 ◽  
Vol 6 (1) ◽  
pp. 30-35 ◽  
Author(s):  
Li Yuwei ◽  
Ai Chi
Keyword(s):  
Hydraulic Fracturing ◽  
Pressure Gauge ◽  
Calculation Model ◽  
Tensile Failure ◽  
Coal Seams ◽  
Rock Body ◽  
Fracture Pressure ◽  
Fracturing Process ◽  
Pressure Calculation ◽  
Initiation Pressure

There are lots of cleats, fractures and many other structure weak planes in coal seams, which make the bullet holes and cleats intersecting. During the hydraulic fracturing process in coal seams, fractures will initiate at coal rock body of borehole wall, and cleats or fractures are different from conventional reservoirs. Thus a new model for initiation pressure calculation during coal seams fracturing should be established. Based on the rock mechanics and elasticity mechanics, and also on network distribution characteristics of coal seam cleats and the space position relationships between the intersected bullet holes and cleats, stress distribution around the bullet holes and at the cleats wall were deducted. The model was established in tensile failure condition. The calculated initiation fracture pressure of Well HX-3 was 10.71MPa. The pressure obtained from bottom hole pressure gauge was 11.24MPa. The relative error was 4.72%. The model could be applied for initiation pressure calculation during hydraulic fracturing process in coal seams. The fractures would initiate at the cleats during fracturing.

Leak-Off Pressure Prediction with the Integration of Fully Coupled 3D DFN Modeling in Fractured Reservoir

2021 ◽  
Author(s):  
Dan Xie ◽  
Wei Zhou ◽  
Sinan Cheng ◽  
Gang Tian ◽  
Sheng Zheng ◽  
...  
Keyword(s):  
Rational Design ◽  
Drilling Fluid ◽  
Prediction Method ◽  
Junggar Basin ◽  
Natural Fracture ◽  
Pressure Curve ◽  
Fractured Reservoir ◽  
Lost Circulation ◽  
Fracture Pressure ◽  
Fully Coupled

Abstract Leak-off pressure is a main factor to induce formation leak-off so that it can be utilized as a crucial parameter to analyze the causation of well leak-off accidents, and that in-depth investigation on leak-off pressure is of vital importance for secure drilling. By analyzing the characteristics of leak-off formation, this paper divides the leak-off into natural leak-off and fractured leak-off, and then defines the conception of minimal leak-off pressure. The leak-off mechanism of fractured formation is investigated. Investigation results show that the currently existent prediction method of fracture pressure is established on the foundations of non-filtration borehole wall assumption as well as the Terzaghi effective stress model. These foundations are not consistent with the practical features of thief formation, which would inevitably cause deviation of calculated results with actualization. Natural leak-off formation constitutes the majority of formation leak-off phenomena. Therefore, it is urgent to build up the leak-off pressure curve instead of fractured pressure curve and take precautions against natural leak-off. The technique of leak-off pressure prediction with fully-coupled 3D natural fracture modeling was applied in the fractured reservoir which located in the northwest of Junggar Basin, China. Case analyses have proved that this lost circulation pressure model is of sufficiency in scientific bases and pertinence. The prediction result derived from the model is relatively consistent with the actual situation and consequently provides a substantial basis for a rational design of the drilling fluid density as well as the leak resistance and sealing. Therefore it is suggested that the design of drilling engineering should take the lost circulation pressure into consideration.

The evolution of lost circulation prevention and mitigation based on wellbore strengthening theory: A review on experimental issues

2022 ◽  
pp. 110149
Author(s):  
Seyed Morteza Mirabbasi ◽  
Mohammad Javad Ameri ◽  
Mortadha Alsaba ◽  
Mohsen Karami ◽  
Amir Zargarbashi
Keyword(s):  
Lost Circulation ◽  
Wellbore Strengthening

Effect of plastic deformation on hydraulic fracturing with extended element method

2018 ◽  
Vol 14 (6) ◽  
pp. 2083-2101 ◽  
Author(s):  
Qingdong Zeng ◽  
Jun Yao ◽  
Jianfu Shao
Keyword(s):  
Plastic Deformation ◽  
Hydraulic Fracturing ◽  
Extended Element ◽  
Element Method

Effect of Drilling Fluid Temperature on Formation Fracture Pressure Gradient

2021 ◽  
Author(s):  
Ahmed Mostafa Samak ◽  
Abdelalim Hashem Elsayed
Keyword(s):  
High Temperature ◽  
Pressure Gradient ◽  
Thermal Effect ◽  
Drilling Fluid ◽  
Wellbore Stability ◽  
Cooling Effect ◽  
Fluid Temperature ◽  
Lost Circulation ◽  
Fracture Pressure ◽  
Downhole Temperature

Abstract During drilling oil, gas, or geothermal wells, the temperature difference between the formation and the drilling fluid will cause a temperature change around the borehole, which will influence the wellbore stresses. This effect on the stresses tends to cause wellbore instability in high temperature formations, which may lead to some problems such as formation break down, loss of circulation, and untrue kick. In this research, a numerical model is presented to simulate downhole temperature changes during circulation then simulate its effect on fracture pressure gradient based on thermo-poro-elasticity theory. This paper also describes an incident occurred during drilling a well in Gulf of Suez and the observations made during this incident. It also gives an analysis of these observations which led to a reasonable explanation of the cause of this incident. This paper shows that the fracture pressure decreases as the temperature of wellbore decreases, and vice versa. The research results could help in determining the suitable drilling fluid density in high-temperature wells. It also could help in understanding loss and gain phenomena in HT wells which may happen due to thermal effect. The thermal effect should be taken into consideration while preparing wellbore stability studies and choosing mud weight of deep wells, HPHT wells, deep water wells, or wells with depleted zones at high depths because cooling effect reduces the wellbore stresses and effective FG. Understanding and controlling cooling effect could help in controlling the reduction in effective FG and so avoid lost circulation and additional unnecessary casing points.

Pre-Drilled ECD Design by Using Fracture Pressure Model in Satun-Funan Fields, Pattani Basin, Gulf of Thailand

2021 ◽  
Author(s):  
Nardthida Kananithikorn ◽  
Teenarat Songsaeng
Keyword(s):  
Poisson’S Ratio ◽  
Linear Trend ◽  
Time Lapse ◽  
Poisson's Ratio ◽  
Gulf Of Thailand ◽  
Local Data ◽  
Good Communication ◽  
Lost Circulation ◽  
Fracture Pressure ◽  
Input Parameters

Abstract Lost circulation is the most common drilling issue for infill drilling projects in Satun-Funan Fields, South Pattani Basin, Gulf of Thailand (GOT). The depleted sand is possible to be a root cause in many wells based on observation from resistivity time-lapse separation in depleted sands or shale nearby. Therefore, the objective of this study is to estimate fracture pressure related to the depleted sand and design an appropriate Equivalent Circulating Density (ECD) threshold for each well to avoid or minimize lost circulation and well control complication during drilling a new well. This study model is using Eaton (1969) equation. There are 3 input parameters which are Poisson's Ratio and pre-drilled estimated depletion pressure and depth. With limitations of no actual fracturing data and limited sonic log, the maximum ECD while lost circulation reading from Pressure While Drilling (PWD) tool and formation pressure test data were used to back-calculate for Poisson's Ratio and identified a relationship with depth. From the total of 68 wells in the Satun and Funan areas, the interpreted Poisson's Ratio ranges from 0.36 to 0.44 and its linear trend is apparently increasing with depth. To minimize the variation of back calculated Poisson's Ratio the local data become an important key for model validation and maintain the similarity of subsurface factors. This interpreted Poisson's ratio trend will be used to calculate for fracture pressure by incorporating with estimated depletion pressure and depth that expect to encounter in each planned well. The lowest fracture pressure in a planned well is used to prepare pre-drilled ECD management plan and a real-time well monitoring plan. Additionally, the model can be adjusted during the operational phase based on the new drilled well result. This alternative model was applied in 4 trial drilling projects in 2019 and fully implement in 6 drilling projects in 2020. The lost circulation can be prevented with value creation from expected gain reserves section is $57M and cost avoidance from non-productive time due to lost circulation is $3.4M. With an effort, good communication and great collaboration among cross-functional teams, the model success rate increases by 12%. However, there are some unexpected lost events occurred even though the maximum ECD lower than expected fracture pressure. This suspect as a combination of limitations and uncertainties on key input parameters and drilling parameters. In the future, the model is planned to expand to other gas fields in the Pattani Basin which will move to more infill phase and have higher chance of getting lost circulation to maximize benefits as the success case in Satun and Funan fields.

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