scholarly journals Liquid–liquid gravity displacement in a vertical fracture during drilling: Experimental study and mathematical model

2019 ◽  
Vol 38 (2) ◽  
pp. 533-554
Author(s):  
Dong Xiao ◽  
Yingfeng Meng ◽  
Xiangyang Zhao ◽  
Gao Li ◽  
Jiaxin Xu
Keyword(s):  
Mathematical Model ◽  
Drilling Fluid ◽  
Effective Means ◽  
Fluid Density ◽  
Shape Factors ◽  
Fracture Width ◽  
Factors Affecting ◽  
Double Substrate ◽  
Fracture Height ◽  
Liquid Displacement

Gravity displacement often occurs when drilling a vertical fractured formation, causing a downhole complexity with risk of blowout and reservoir damage, well control difficulty, drilling cycle prolongation, and increased costs. Based on an experimental device created for simulating the gravity displacement, various factors affecting the displacement quantity were quantitatively evaluated by simulating the fracture width, asphalt viscosity, drilling fluid density, and viscosity under different working conditions, and a liquid–liquid displacement law was obtained. Using the theories of rock mechanics, fluid mechanics, and seepage mechanics, based on conformal mapping, as well as a fracture-pore double substrate fluid flow model, we established a steady-state mathematical model of fractured formation liquid–liquid gravity displacement by optimizing the shape factors and using a combination of gravity displacement experiments to verify the feasibility of the mathematical model. We analyzed the influence of drilling fluid density, fracture height and length, and asphalt viscosity on displacement rate, and obtained the corresponding laws. The results show that when the oil–fluid interface is stable, the fracture width is the most important factor affecting the gravity displacement, and plugging is the most effective means of managing gravity displacement.

scholarly journals Analysis of factors affecting drilling friction and investigation of the friction reduction tool in horizontal wells in Sichuan

2019 ◽  
Vol 11 (7) ◽  
pp. 168781401986296 ◽  
Author(s):  
Yong Chen ◽  
Chuan He ◽  
Xu Zhou ◽  
Hao Yu
Keyword(s):  
Horizontal Well ◽  
Drilling Fluid ◽  
Drill Pipe ◽  
Drill String ◽  
Friction Reduction ◽  
Fluid Density ◽  
Horizontal Section ◽  
Well Drilling ◽  
Factors Affecting ◽  
The Mathematical Model

Based on field data and the related theories, the effects of drill string length, rotation speed, trajectory, and drilling fluid density on the friction during horizontal well drilling are analyzed in Sichuan. With increasing the length of drill string in the horizontal section, the friction grows. The drill pipe rotates faster and the torque decreases. Large undulation of borehole deviation and the “W” shape of the horizontal section lead to excessive friction. A higher fluid density causes higher torque and drag. Moreover, a friction reduction tool is designed to reduce friction, decrease the wear between the casing and the drill pipe joint, and prevent the differential pressure sticking, which improves the rate of penetration, and the specially designed spiral diversion channels improve the efficiency of borehole cleaning. The field experimental results have shown that the accumulated operational time of the friction reduction tool is more than 130 h and its fatigue life reaches up to 3 × 105 cycles. A plan of improving the tool structure is proposed to reduce the mud balling after the experiment. Finally, the mathematical model of calculating the spacing of the friction reduction tools is established, which provides technical support for investigating the friction in horizontal well drilling.

MODELING OF THE DYNAMIC PROCESS RELEASE OF STUCK DRILLING TOOLS BY HYDRO-PULSE METHOD

2019 ◽  
pp. 94-103
Author(s):  
K. H. Levchyk ◽  
M. V. Shcherbyna
Keyword(s):  
Mathematical Model ◽  
Dynamic Process ◽  
Drilling Fluid ◽  
Pulse Method ◽  
Geometrical Parameters ◽  
Technical Solution ◽  
Rock Layer ◽  
Drilling Tool ◽  
Drilling Tools ◽  
Drill Pipes

A technical solution is proposed for the elimination the grabbing of drilling tool, based on the use of energy due to the circulation of the drilling fluid. The expediency eliminating the grabbing drilling tool using the hydro-impulse method is substantiated. A method of drawing up a mathematical model for the dynamic process of a grabbing string of drill pipes in the case of perturbation of hydro-impulse oscillations in the area of the productive rock layer is developed. The law of longitudinal displacements arising in the trapped string is obtained, which allows choosing the optimal geometrical parameters of the passage channels and the frequency rotational of shutter for these channels. Recommendations for using this method for practical use have been systematized.

A Novel Method to Determine the Drilling Fluid Density for Gypsum-Salt Layer

2021 ◽  
Author(s):  
Jitong Liu ◽  
Wanjun Li ◽  
Haiqiu Zhou ◽  
Yixin Gu ◽  
Fuhua Jiang ◽  
...  
Keyword(s):  
Drilling Fluid ◽  
In Situ Stress ◽  
Wellbore Stability ◽  
Shrinkage Rate ◽  
Fluid Density ◽  
Salt Layer ◽  
Rock Creep ◽  
Key Factor ◽  
Well Abandonment

Abstract The reservoir underneath the salt bed usually has high formation pressure and large production rate. However, downhole complexities such as wellbore shrinkage, stuck pipe, casing deformation and brine crystallization prone to occur in the drilling and completion of the salt bed. The drilling safety is affected and may lead to the failure of drilling to the target reservoir. The drilling fluid density is the key factor to maintain the salt bed’s wellbore stability. The in-situ stress of the composite salt bed (gypsum-salt -gypsum-salt-gypsum) is usually uneven distributed. Creep deformation and wellbore shrinkage affect each other within layers. The wellbore stability is difficult to maintain. Limited theorical reference existed for drilling fluid density selection to mitigate the borehole shrinkage in the composite gypsum-salt layers. This paper established a composite gypsum-salt model based on the rock mechanism and experiments, and a safe-drilling density selection layout is formed to solve the borehole shrinkage problem. This study provides fundamental basis for drilling fluid density selection for gypsum-salt layers. The experiment results show that, with the same drilling fluid density, the borehole shrinkage rate of the minimum horizontal in-situ stress azimuth is higher than that of the maximum horizontal in-situ stress azimuth. However, the borehole shrinkage rate of the gypsum layer is higher than salt layer. The hydration expansion of the gypsum is the dominant reason for the shrinkage of the composite salt-gypsum layer. In order to mitigate the borehole diameter reduction, the drilling fluid density is determined that can lower the creep rate less than 0.001, as a result, the borehole shrinkage of salt-gypsum layer is slowed. At the same time, it is necessary to improve the salinity, filter loss and plugging ability of the drilling fluid to inhibit the creep of the soft shale formation. The research results provide technical support for the safe drilling of composite salt-gypsum layers. This achievement has been applied to 135 wells in the Amu Darya, which completely solved the of wellbore shrinkage problem caused by salt rock creep. Complexities such as stuck string and well abandonment due to high-pressure brine crystallization are eliminated. The drilling cycle is shortened by 21% and the drilling costs is reduced by 15%.

Simulation of oscillatory processes in the MVSTUDIUM package

2022 ◽  
Vol 14 (4) ◽  
pp. 139-148
Author(s):  
Aleksandr Poluektov ◽  
Konstantin Zolnikov ◽  
V. Antsiferova
Keyword(s):  
Mathematical Model ◽  
Friction Force ◽  
Computer Models ◽  
3D Models ◽  
Oscillatory Process ◽  
Suspension Point ◽  
Factors Affecting ◽  
2D And 3D ◽  
The Mathematical Model ◽  
Oscillatory Processes

The mathematical model and algorithms of oscillatory movements are considered. Various factors affecting the oscillatory process are considered. Oscillatory movements are constructed in the MVSTUDIUM modeling environment. The schemes of three computer models demonstrating oscillatory processes are determined: a model of a pendulum with a non-movable suspension point, a model of a pushing pendulum with friction force and a model of a breaking pendulum. Classes are being built to execute models with embedded properties, as well as with the ability to export the created classes to other models, and embed classes created by the program developer into the model. Creation of 2D and 3D models of oscillatory processes, an experiment behavior map and a virtual stand.

Density and Drag Reduction With Hollow Glass Additives

2014 ◽  
Author(s):  
Bahri Kutlu ◽  
Evren M. Ozbayoglu ◽  
Stefan Z. Miska ◽  
Nicholas Takach ◽  
Mengjiao Yu ◽  
...  
Keyword(s):  
Drag Reduction ◽  
Rheological Behavior ◽  
Drilling Fluid ◽  
Hydraulic Drag ◽  
Effect Of Temperature ◽  
Survival Ratio ◽  
Fluid Density ◽  
Hollow Glass ◽  
Glass Spheres ◽  
Reduction Effect

This study concentrates on the use of materials known as hollow glass spheres, also known as glass bubbles, to reduce the drilling fluid density below the base fluid density without introducing a compressible phase to the wellbore. Four types of lightweight glass spheres with different physical properties were tested for their impact on rheological behavior, density reduction effect, survival ratio at elevated pressures and hydraulic drag reduction effect when mixed with water based fluids. A Fann75 HPHT viscometer and a flow loop were used for the experiments. Results show that glass spheres successfully reduce the density of the base drilling fluid while maintaining an average of 0.93 survival ratio, the rheological behavior of the tested fluids at elevated concentrations of glass bubbles is similar to the rheological behavior of conventional drilling fluids and hydraulic drag reduction is present up to certain concentrations. All results were integrated into hydraulics calculations for a wellbore scenario that accounts for the effect of temperature and pressure on rheological properties, as well as the effect of glass bubble concentration on mud temperature distribution along the wellbore. The effect of drag reduction was also considered in the calculations.

scholarly journals Study on Method of Determining the Safe Operation Window of Drilling Fluid Density with Credibility in Deep Igneous Rock Strata

2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
Chao Han ◽  
Zhichuan Guan ◽  
Chuanbin Xu ◽  
Fuhui Lai ◽  
Pengfei Li
Keyword(s):  
Igneous Rock ◽  
Drilling Fluid ◽  
Prediction Method ◽  
Large Error ◽  
Fluid Density ◽  
Safe Operation ◽  
Collapse Pressure ◽  
Modified Method ◽  
Fracture Pressure ◽  
Rock Strata

It is difficult to determine the safe operation window of drilling fluid density (SOWDFD) for deep igneous rock strata. Although the formation three-pressure (pore pressure, collapse pressure, and fracture pressure) prediction method with credibility improves the accuracy of formation three-pressure prediction, it still has a large error for deep igneous strata. To solve this problem, a modified method of the SOWDFD in deep igneous rock strata is proposed based on the leakage statistics of adjacent wells. This method is based on the establishment of the SOWDFD with credibility. Through statistical analysis of drilling fluid density of igneous rock leaky formation group in adjacent wells, the fracture leakage law of the formation is revealed and the upper limit of leak-off pressure containing probability information is obtained. Finally, the modified SOWDFD with credibility for deep igneous rock strata is formed. In this work, the proposed method was used to compute the SOWDFD with credibility of SHB well in Xinjiang, China. Results show that the modified density window is consistent with the field drilling conditions and can reflect the narrow density window in the Permian and lower igneous strata. Combined with the formation three-pressure prediction method with credibility and the actual leakage law of adjacent wells, it can effectively improve the prediction accuracy of the SOWDFD for deep igneous rock strata. The findings of the study can help in better understanding of the complex downhole geological environment in deep igneous rock strata and making reasonable drilling design scheme.

scholarly journals OPTIMISATION OF HYDRAULIC FRACTURING DESIGN IN LOWER OLIGOCENE RESERVOIR, KINH NGU TRANG OILFIELD

2018 ◽  
Vol 18 (3) ◽  
pp. 323-337
Author(s):  
Nguyen Huu Truong
Keyword(s):  
Hydraulic Fracturing ◽  
Complex Structure ◽  
Power Requirement ◽  
Fracture Conductivity ◽  
Fracture Width ◽  
The North ◽  
Fracture Closure ◽  
Average Water ◽  
White Tiger ◽  
Fracture Height

Kinh Ngu Trang oilfield is of the block 09-2/09 offshore Vietnam, which is located in the Cuu Long basin, the distance from that field to Port of Vung Tau is around 140 km and it is about 14 km from the north of Rang Dong oilfield of the block 15.2, and around 50 km from the east of White Tiger in the block 09.1. That block accounts for total area of 992 km2 with the average water depth of around 50 m to 70 m. The characteristic of Oligocene E reservoir is tight oil in sandstone, very complicated with complex structure. Therefore, the big challenges in this reservoir are the low permeability and the low porosity of around 0.2 md to less than 1 md and 1% to less than 13%, respectively, leading to very low fracture conductivity among the fractures. Through the Minifrac test for reservoir with reservoir depth from 3,501 mMD to 3,525 mMD, the total leak-off coefficient and fracture closure pressure were determined as 0.005 ft/min0.5 and 9,100 psi, respectively. To create new fracture dimensions, hydraulic fracturing stimulation has been used to stimulate this reservoir, including proppant selection and fluid selection, pump power requirement. In this article, the authors present optimisation of hydraulic fracturing design using unified fracture design, the results show that optimum fracture dimensions include fracture half-length, fracture width and fracture height of 216 m, 0.34 inches and 31 m, respectively when using proppant mass of 150,000 lbs of 20/40 ISP Carbolite Ceramic proppant.

scholarly journals Analysis on Present Mathematical Model for Predicting the Crop Production

2020 ◽  
Vol 9 (12) ◽  
pp. 168-170
Keyword(s):  
Mathematical Model ◽  
Mathematical Models ◽  
Real World ◽  
Crop Production ◽  
Ghg Emissions ◽  
Data Set ◽  
Factors Affecting ◽  
The Government ◽  
The Mathematical Model ◽  
Government Website

India is a worldwide agriculture business powerhouse. Future of agriculture-based products depends on the crop production. A mathematical model might be characterized as a lot of equations that speak to the conduct of a framework. By using mathematical model in agriculture field, we can predict the production of crop in particular area. There are various factors affecting crops such as Rainfall, GHG Emissions, Temperature, Urbanization, climate, humidity etc. A mathematical model is a simplified representation of a real-world system. It forms the system using mathematical principles in the form of a condition or a set of conditions. Suppose we need to increase the crop production, at that time the mathematical model plays a major role and our work can be easier, more significant by using the mathematical model. Through the mathematical model we predict the crop production in upcoming years. .AI, ML, IOT play a major role to predict the future of agriculture, but without mathematical models it is not possible to predict crop production accurately. To solve the real-world agriculture problem, mathematical models play a major role for accurate results. Correlation Analysis, Multiple Regression analysis and fuzzy logic simulation standards have been utilized for building a grain production benefit depending model from crop production. Prediction of crop is beneficiary to the farmer to analyze the crop management. By using the present agriculture data set which is available on the government website, we can build a mathematical model.

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