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.

Study on Borehole Stability of Unconsolidated Sandstone in Depleted Reservior

2012 ◽  
Vol 616-618 ◽  
pp. 720-725
Author(s):  
Qiang Tan ◽  
Jin Gen Deng ◽  
Bao Hua Yu
Keyword(s):  
Oil And Gas ◽  
Drilling Fluid ◽  
Wellbore Stability ◽  
Formation Pressure ◽  
Borehole Stability ◽  
Oil And Gas Development ◽  
Collapse Pressure ◽  
Lost Circulation ◽  
Fracture Pressure ◽  
Pressure Depletion

Reservoir pressure will decline generally along with production in the oil and gas development process. There are some problems such as borehole collapse or reduced diameter and lost circulation in drilling of initial production stage in unconsolidated sandstone. As the formation pressure declines the stress around borehole changes, and then collapse pressure and fracture pressure are affected. Especially in directional wells, variation of wellbore stability is more complex with different borehole deviation and azimuth. The calculation models of collapse and fracture pressure in depleted reservoirs were established, and relevant data in unconsolidated sand reservoir of an oilfield in Bohai Sea was used to calculate collapse pressure and fracture pressure of directional wells in the condition of pressure depletion before and after. The results showed that collapse and fracture pressure decreased as formation pressure depletion, and safe drilling fluid density window was wider when drilled to the direction of minimum horizontal principle stress. The calculation results can be reference to drilling design of adjustment wells in unconsolidated sandstones.

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.

Borehole Temperature Modelling in High Temperature Drilling Environment Based on Heat Transfer Laws

2019 ◽  
Author(s):  
Abhijeet D. Chodankar ◽  
Cheng-Xian Lin
Keyword(s):  
Heat Transfer ◽  
High Temperature ◽  
Drilling Fluid ◽  
Drill String ◽  
Wellbore Stability ◽  
Heat Transfer Analysis ◽  
Drilling Fluids ◽  
Concentric Cylinder ◽  
Composite Wall ◽  
Borehole Temperature

Abstract High temperature drilling environment has a drastic effect on drilling fluids, wellbore stability, and drilling system components. It has been observed that drilling fluids displace conventional halide based fluids in High Pressure and High Temperature (HPHT) wells leading to corrosion and environmental hazards, while wellbore strengthens further as a result of an increase in fracture initiation pressure in high temperature environment. However, it seriously damages the downhole tools like sensors, elastomer dynamic seals, lithium batteries, electronic component and boards leading to increases in cost and non-productive time. The main objective of this paper is to present an analytical borehole temperature model based on classical heat transfer laws in a high temperature drilling environment. The borehole is modelled using two approaches: composite wall and concentric cylinders. The composite wall and concentric cylinder approaches consist layers of geological formations, drilling fluids outside the drill string, drill string, and drilling fluid inside the drill string. Temperature, heat transfer coefficient, and heat transfer variations along the borehole layers are determined using the derived analytical solutions and tested for different drilling fluid types, air drilling environment, and different drill string materials. The results of composite wall and concentric cylinder models are obtained by using the input field temperatures data in the geological formation and inner annulus of drill pipe to determine the borehole temperature profile in HPHT wells. Therefore, a thorough borehole heat transfer analysis will help in wellbore stability, drilling fluid selection, corrosion control, and optimal placement and material selection of drilling components in HPHT drilling environments.

Integrated Experimental and Analytical Wellbore Strengthening Solutions by Mud Plastering Effects

2016 ◽  
Vol 138 (3) ◽  
Author(s):  
Saeed Salehi ◽  
Raj Kiran
Keyword(s):  
High Pressure ◽  
High Temperature ◽  
Drilling Fluid ◽  
Wellbore Stability ◽  
Stress Profile ◽  
Laboratory Studies ◽  
Mud Cake ◽  
Stress Changes ◽  
Wellbore Strengthening ◽  
The Impact

Wellbore stability has plagued oil industry for decades. Inclusion of the mud in drilling and the effect of mud cake build up incorporate very complex chemical, thermal, mechanical, and physical phenomena. It is very difficult to quantify all these phenomena in one model. The after effects of mud cake buildup, its permeability and variation in thickness with time alter the actual stress profile of the formation. To see the impact of the whole mechanism, a combination of laboratory studies and numerical modeling is needed. This paper includes the procedure and results on stress profiles in near wellbore region based on laboratory studies of mud cake buildup in high pressure and high temperature environment using permeability plug apparatus (PPA). The damaged formation zone is very susceptible to drilling fluid and results in alteration of existing pore pressure and fracture pressure. This paper presents integrated experimental and analytical solutions for wellbore strengthening due to mud cake plastering. Conducting experiments on rock core disks has provided more realistic results which can resemble to field conditions. The experimental work here provides an insight to effect of mud cake build up at high pressure and high temperature conditions using a heterogeneous filtration medium prepared from different sandstone cores. Results were used in the analytical model to see the effect of stresses in the formation. The primary objective is to investigate the wellbore hoop stress changes due to formation of filter cake by mud plastering using the analytical models built upon the laboratory results. The models developed in this work provide insights to quantify on wellbore plastering effects by mud cake build up.

A Steady-State Approach for Surge and Swab Pressures Calculation of Herschel-Buckley Fluids in Directional/Horizontal Wells

2016 ◽  
Author(s):  
Wenlong Jiang ◽  
Honghai Fan ◽  
Rongyi Ji ◽  
Deqiang Tian ◽  
Zixiang Wen ◽  
...  
Keyword(s):  
Pressure Gradient ◽  
Flow Rate ◽  
Flow Model ◽  
Drilling Fluid ◽  
Flow Behavior ◽  
Fluid Velocity ◽  
Velocity Model ◽  
Bingham Plastic ◽  
Eccentric Annulus ◽  
Lost Circulation

ABSTRACT Surge and swab pressures have been known as one of the most important factors for formation fracture, lost circulation and well control problems. Previous surge/swab pressures models are mostly based on Bingham plastic (BP) or Power law (PL) fluids, which cannot adequately describe the flow behavior of drilling fluid. This paper presents a new model for computing surge/swab pressures of Herschel-Buckley (HB) fluids in horizontal/directional wells which involves the effect of eccentric annuli. A axial laminar flow model in eccentric annulus is developed using narrow slot flow model with the H-B rheological model. The drilling fluid velocity model caused by the moving drillstring is developed, through which the flow rate can be calculated. Based on the equal flow rate from the flow model and the drilling fluid velocity model, the pressure gradient equation is obtained. The numerical solution of the pressure gradient is calculated utilizing adaptive Simpson integral method which is of high accuracy. Lastly, a case study is conducted. The model proposed in the current study is meaningful for safety drilling.

Impact of Multi-Branched Ionic Liquid on Shale Swelling and Hydration for High Temperature Drilling Applications

2021 ◽  
Author(s):  
Rizwan Ahmed Khan ◽  
Hafiz Mudaser Ahmad ◽  
Mobeen Murtaza ◽  
Abdulazeez Abdulraheem ◽  
Muhammad Shahzad Kamal ◽  
...  
Keyword(s):  
Contact Angle ◽  
Ionic Liquid ◽  
High Temperature ◽  
Hot Rolling ◽  
Drilling Fluid ◽  
Wellbore Stability ◽  
Drilling Fluids ◽  
Swell Index ◽  
Clay Surface ◽  
Shale Recovery

Abstract Shale swelling and hydration during the drilling operation have adverse effects on the stability of a wellbore. Hydrophilic interactions of shale results in swelling and disintegration of the shale formation. This paper discusses wettability changes and hydration characteristics of shale to improve the wellbore stability. The use of multibranched ionic liquid as drilling fluid for high temperature applications was investigated. The novel multibranched ionic liquid (Trihexyltetradecyl phosphonium bis (2,4,4-trimethyl pentyl) phosphinate, denoted as Tpb-P) water-based drilling fluid was prepared by mixing different concentrations of ionic liquid and other additives such as filtration controller, rheological modifier, and pH controller. The wettability of bentonite powder was determined using a contact angle in the presence of various concentrations of ionic liquids. Several other experimental techniques, such as linear swelling, hot rolling recovery, and bentonite swell index, were used to examine the inhibition performance of ionic liquid. The rheology and filtration properties of ionic liquid-based drilling fluid were also examined. Various concentrations of multibranched ionic liquid were used to formulate the drilling fluids ranging from (0.1 to 0.5 wt.%), and their performances were compared with the base drilling fluid prepared without ionic liquid. The hydrophobicity of the shale surface was determined by measuring the contact angle, and results showed that drilling fluid having 0.1 wt.% concentration of ionic liquid has a maximum contact angle indicating the highly hydrophobic shale surface. The hot rolling shale recovery experiment was conducted at 150°F, and it was observed that adding ionic liquid improved the shale recovery (24.4%) compared to the base fluid recovery (12.8%). The linear swelling was evaluated over the time of 24 hours, and the least swelling of bentonite was noticed with 0.1 wt.% ionic liquid (98.1%) compared to linear swelling in deionized water (125%). The results suggested that the ionic liquid in the drilling fluid chemically interacted with the clay surface and reduced the hydrophilicity of clay, which restricts the exchange of water onto the clay surface.

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.

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