scholarly journals Chemical Effect on Wellbore Instability of Nahr Umr Shale

2013 ◽  
Vol 2013 ◽  
pp. 1-7 ◽  
Author(s):  
Baohua Yu ◽  
Chuanliang Yan ◽  
Zhen Nie
Keyword(s):  
Drilling Fluid ◽  
Ionic Concentration ◽  
Chemical Effect ◽  
Drilling Fluids ◽  
Collapse Pressure ◽  
Wellbore Instability ◽  
Sealing Capacity ◽  
Engineering Data ◽  
Forward Engineering ◽  
Rock Mechanical Properties

Wellbore instability is one of the major problems that hamper the drilling speed in Halfaya Oilfield. Comprehensive analysis of geological and engineering data indicates that Halfaya Oilfield features fractured shale in the Nahr Umr Formation. Complex accidents such as wellbore collapse and sticking emerged frequently in this formation. Tests and theoretical analysis revealed that wellbore instability in the Halfaya Oilfield was influenced by chemical effect of fractured shale and the formation water with high ionic concentration. The influence of three types of drilling fluids on the rock mechanical properties of Nahr Umr Shale is tested, and time-dependent collapse pressure is calculated. Finally, we put forward engineering countermeasures for safety drilling in Halfaya Oilfield and point out that increasing the ionic concentration and improving the sealing capacity of the drilling fluid are the way to keep the wellbore stable.

scholarly journals Experimental study of Zubair shale stability of east Baghdad oil field using different additives in water based mud

2019 ◽  
Vol 10 (3) ◽  
pp. 1215-1225
Author(s):  
Asawer A. Alwassiti ◽  
Mayssaa Ali AL-Bidry ◽  
Khalid Mohammed
Keyword(s):  
Drilling Fluid ◽  
Oil Field ◽  
Oil Fields ◽  
Drilling Fluids ◽  
Fluid Type ◽  
Wellbore Instability ◽  
Immersion Period ◽  
Shale Formation ◽  
Shale Recovery ◽  
Polymer Type

AbstractShale formation is represented as one of the challenge formations during drilling wells because it is a strong potential for wellbore instability. Zubair formation in Iraqi oil fields (East Baghdad) is located at a depth from 3044.3 to 3444 m. It is considered as one of the most problematic formations through drilling wells in East Baghdad. Most problems of Zubair shale are swelling, sloughing, caving, cementing problem and casing landing problem caused by the interaction of drilling fluid with the formation. An attempt to solve the cause of these problems has been adapted in this paper by enhancing the shale stability through adding additives to the drilling fluid. The study includes experiments by using two types of drilling fluids, API and polymer type, with five types of additives (KCl, NaCl, CaCl2, Na2SiO3 and Flodrill PAM 1040) in different concentrations (0.5, 1, 5 and 10) wt% and different immersion period (1, 24 and 72 h) hours. The effect of drilling fluids and additive salts on shale has been studied by using different techniques: (XRD, XRF, reflected and transmitted microscope) as well shale recovery. The results show that adding 10 wt% of Na2SiO3 to API drilling fluid results in a high percentage of shale recovery (78.22%), while the maximum shale recovery was (80.57%) in polymer drilling fluid type gained by adding 10 wt% of Na2SiO3.

scholarly journals Oil-Based Drilling Fluid Plugging Method for Strengthening Wellbore Stability of Shale Gas

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-13
Author(s):  
Pengcheng Wu ◽  
Chengxu Zhong ◽  
Zhengtao Li ◽  
Zhen Zhang ◽  
Zhiyuan Wang ◽  
...  
Keyword(s):  
Shale Gas ◽  
Drilling Fluid ◽  
Wellbore Stability ◽  
Drilling Fluids ◽  
Fluid System ◽  
Horizontal Drilling ◽  
Wellbore Instability ◽  
Filtration Loss ◽  
Treatment Agent ◽  
Stability Method

Finding out the reasons for wellbore instability in the Longmaxi Formation and Wufeng Formation and putting forward drilling fluid technical countermeasures to strengthen and stabilize the wellbore are very crucial to horizontal drilling. Based on X-ray diffraction, electron microscope scanning, linear swelling experiment, and hot-rolling dispersion experiment, the physicochemical mechanism of wellbore instability in complex strata was revealed, and thus, the coordinated wellbore stability method can be put forward, which is “strengthening plugging of micropores, inhibiting filtrate invasion, and retarding pressure transmission.” Using a sand bed filtration tester, high-temperature and high-pressure plugging simulation experimental device, and microporous membrane and other experimental devices, the oil-based drilling fluid treatment agent was researched and selected, and a set of an enhanced plugging drilling fluid system suitable for shale gas horizontal well was constructed. Its temperature resistance is 135°C and it has preferable contamination resistibility (10% NaCl, 1% CaCl2, and 8% poor clay). The bearing capacity of a 400 μm fracture is 5 MPa, and the filtration loss of 0.22 μm and 0.45 μm microporous membranes is zero. Compared with previous field drilling fluids, the constructed oil-based drilling fluid system has a greatly improved plugging ability and excellent performance in other aspects.

Wellbore Shielding Technique Increases Operative Window, Avoiding Formation Instability and Losses, Minimizing NPT, and Optimizing Drilling Operations in the Unconventional Plays

2021 ◽  
Author(s):  
Gaston Lopez ◽  
Gonzalo Vidal ◽  
Claus Hedegaard ◽  
Reinaldo Maldonado
Keyword(s):  
Drilling Fluid ◽  
Drilling Fluids ◽  
Wellbore Instability ◽  
Lost Circulation ◽  
Drilling Performance ◽  
Drilling Parameters ◽  
Vaca Muerta ◽  
Drilling Operations ◽  
Fracture Gradient ◽  
Vaca Muerta Formation

Abstract Losses, wellbore instability, and influxes during drillings operations in unconventional fields result from continuous reactivity to the drilling fluid causing instability in the microfractured limestone of the Quintuco Formation in Argentina. This volatile situation becomes more critical when drilling operations are navigating horizontally through the Vaca Muerta Formation, a bituminous marlstone with a higher density than the Quintuco Formation. Controlling drilling fluids invasion between the communicating microfractures and connecting pores helps to minimize seepage losses, total losses, wellbore fluid influxes, and instabilities, reducing the non-productive time (NPT) caused by these problems during drilling operations. The use of conventional sealants – like calcium carbonate, graphite, asphalt, and other bridging materials – does not guarantee problem-free drilling operations. Also, lost circulation material (LCM) is restricted because the MWD-LWD tools clearances are very narrow in these slim holes. The challenge is to generate a strong and resistant seal separating the drilling fluid and the formation. Using an ultra-low-invasion technology will increase the operative fracture gradient window, avoid fluid invasion to the formation, minimize losses, and stop the cycle of fluid invasion and instability, allowing operations to maintain the designed drilling parameters and objectives safely. The ultra-low-invasion wellbore shielding technology has been applied in various fields, resulting in significantly improved drilling efficiencies compared to offset wells. The operator has benefited from the minimization of drilling fluids costs and optimization in drilling operations, including reducing the volume of oil-based drilling fluids used per well, fewer casing sections, and fewer requirements for cementing intervals to solve lost circulation problems. This paper will discuss the design of the ultra-low-invasion technology in an oil-based drilling fluid, the strategy for determining the technical limits for application, the evaluation of the operative window with an increase in the fracture gradient, the optimized drilling performance, and reduction in costs, including the elimination of NPT caused by wellbore instability.

Study on Shale Gas Drilling Fluids Technology

2013 ◽  
Vol 868 ◽  
pp. 651-656
Author(s):  
Gang Xie ◽  
Ming Yi Deng ◽  
Jun Lin Su ◽  
Liang Chun Pu
Keyword(s):  
Shale Gas ◽  
Drilling Fluid ◽  
Blocking Agent ◽  
Drilling Fluids ◽  
Collapse Pressure ◽  
Gas Drilling ◽  
Advantages And Disadvantages ◽  
Water Based ◽  
Column Pressure ◽  
Shale Gas Drilling

Via discussing the advantages and disadvantages of different types of oil-based drilling fluids, the main reason why oil-based drilling fluids are less used in our country is obtained that dont form a complete series of matching technology. The essence of wellbore instability caused by using water-based drilling fluids to drill shale is analyzed that the formation collapse pressure is greater than drilling fluids column pressure. The fundamental way of controlling borehole wall stability that use water-based drilling fluids to drill shale horizontal well was proposed that deeply researched the shale hydration mechanism, developed efficient blocking agent and inhibitors and established shale gas drilling fluid suppression system, which made water-based drilling fluids have excellent performance.

Application of Artificial Clay Samples (Pellets) in Laboratory Testing of Shale/Drilling Fluid Interaction

2013 ◽  
Author(s):  
Borivoje Pasic ◽  
Nediljka Gaurina-Medjimurec ◽  
Bojan Moslavac
Keyword(s):  
Laboratory Testing ◽  
Drilling Fluid ◽  
Petroleum Industry ◽  
Drilling Fluids ◽  
Surface Sampling ◽  
Laboratory Equipment ◽  
Wellbore Instability ◽  
Research Activities ◽  
Physico Chemical ◽  
Fluid Interaction

Wellbore instability was and is one of the most frequent problems in petroleum industry, especially in the drilling operations. It is mainly caused by the shale formations which represent 75% of all drilled formations. The wellbore instability problems involve tight hole spots, wellbore diameter enlargement, the appearance of cavings, the inability of carrying out wireline operations, poor hole cleaning, unsuccessful wellbore cementing operations and other. The wellbore instability is the result of mechanical and physico-chemical causes mostly acting concurrently. The shale instability basically comes out of its mineralogical composition (especially clay minerals content) and physico-chemical properties. Shale-mud interaction includes water/ions movement in and out of the shales due to pressure differential, osmosis, diffusive flow and capillary pressure. Many research activities about shale instability causes and shale properties (affecting shale behavior) definition have been carried out by now. Different shale samples, laboratory equipment and inhibitive muds have been used. Laboratory tested shale samples are provided by the wellbore cores, surface sampling or, which is the simplest method, by collecting the samples at the shale shakers during drilling operation. The amount of these samples is not enough for laboratory testing. Another problem is closely connected to sample quality and preservation. There are also differences in drilling fluids used in these laboratory tests, especially in their composition (sometimes containing more than one shale inhibitor). It is difficult to compare test results and conclusions made by different authors. The laboratory study presented within this paper are done with artificial clay samples (pellets) made by compacting the powderish material containing exact quantity of quartz, montmorillonite and kaolinite. The laboratory testing is done by treating the powderish samples inside the desiccator (24 hours), compacting (30 minutes), swelling (24 hours) and drying samples (24-hour). Sample swelling is tested by using different mud types and the sample mass is measured in each above mentioned phase. Special attention is directed to preparation and pellets content definition as a good replacement for the original shale in laboratory testing of shale and drilling fluid interaction. The influence of used muds on the total pellet swelling and swelling intensity, especially at the early phase of testing was determined.

The Influence of SiO2 and TiO2 Nanoparticles on the Properties of Water-Based Mud

2017 ◽  
Author(s):  
Petar Mijić ◽  
Nediljka Gaurina-Međimurec ◽  
Borivoje Pašić
Keyword(s):  
Filter Cake ◽  
Drilling Fluid ◽  
Wellbore Stability ◽  
Drilling Fluids ◽  
Drilling Mud ◽  
Shale Formations ◽  
Wellbore Instability ◽  
Water Based ◽  
Fluid Properties

About 75% of all formations drilled worldwide are shale formations and 90% of all wellbore instability problems occur in shale formations. This increases the overall cost of drilling. Therefore, drilling through shale formations, which have nanosized pores with nanodarcy permeability still need better solutions since the additives used in the conventional drilling fluids are too large to plug them. One of the solutions to drilling problems can be adjusting drilling fluid properties by adding nanoparticles. Drilling mud with nanoparticles can physically plug nanosized pores in shale formations and thus reduce the shale permeability, which results in reducing the pressure transmission and improving wellbore stability. Furthermore, the drilling fluid with nanoparticles, creates a very thin, low permeability filter cake resulting in the reduction of the filtrate penetration into the shale. This thin filter cake implies high potential for reducing the differential pressure sticking. In addition, borehole problems such as too high drag and torque can be reduced by adding nanoparticles to drilling fluids. This paper presents the results of laboratory examination of the influence of commercially available nanoparticles of SiO2 (dry SiO2 and water-based dispersion of 30 wt% of silica), and TiO2 (water-based dispersion of 40 wt% of titania) in concentrations of 0.5 wt% and 1 wt% on the properties of water-based fluids. Special emphasis is put on the determination of lubricating properties of the water-based drilling fluids. Nanoparticles added to the base mud without any lubricant do not improve its lubricity performance, regardless of their concentrations and type. However, by adding 0.5 wt% SiO2-disp to the base mud with lubricant, its lubricity coefficient is reduced by 4.6%, and by adding 1 wt% TiO2-disp to the base mud with lubricant, its lubricity coefficient is reduced by 14.3%.

scholarly journals New insight on studying the effect of both chemical sensitivity and rock mechanical properties in shale formation to minimize wellbore instability problems

2020 ◽  
Vol 205 ◽  
pp. 03012
Author(s):  
Mohammad H. Alqam ◽  
Hazim H. Abass ◽  
Abdullah M. Shebatalhmad
Keyword(s):  
Drilling Fluid ◽  
Wellbore Stability ◽  
High Porosity ◽  
Shale Formations ◽  
Wellbore Instability ◽  
Testing Procedures ◽  
Shale Formation ◽  
Rock Mechanical Properties ◽  
Core Volume ◽  
Shale Permeability

Historically, many of the wells drilled in in shale formations have experienced a significant rig downtime due to wellbore instabilities. Most of the instability problems originated from the encountered shale formations. The objectives of this study include (1) to measure the properties governing shale strength and drilling fluid/shale interaction, and (2) to establish a reliable and efficient rock mechanical testing procedures related to wellbore stability. Preserved shale core has been recovered from shale formation and special core handling procedure was implemented. Mineral oil was used for plugging and core preservation. Rock mechanical characterization was conducted on core samples using both XRD/SEM techniques to study the core mineralogy. In addition, shale permeability was determined by two methods: flow testing and pressure transition methods. The results indicated that shale has high percentage of quartz (30-40%) which causes the shale to have high porosity and high permeability. The unconfined compressive strength of shale is very low which any drilling fluid that contains water phase further reduces. The Young’s modulus is very low which makes near wellbore deformation high. Based on the shale swelling testing, the all-oil fluid show no volume change occurred to the shale. When the same shale was exposed to the 7% KCl, about 16% increase in core volume occurred in 48 hours. This means that all samples allowed the water to flow into the shale formation.

scholarly journals Probabilistic Approach in Wellbore Stability Analysis during Drilling

2016 ◽  
Vol 2016 ◽  
pp. 1-13 ◽  
Author(s):  
Mahmood R. Al-Khayari ◽  
Adel M. Al-Ajmi ◽  
Yahya Al-Wahaibi
Keyword(s):  
Deterministic Model ◽  
Drilling Fluid ◽  
Probabilistic Approach ◽  
Fluid Pressure ◽  
Wellbore Stability ◽  
Rock Properties ◽  
Well Drilling ◽  
Collapse Pressure ◽  
Wellbore Instability

In oil industry, wellbore instability is the most costly problem that a well drilling operation may encounter. One reason for wellbore failure can be related to ignoring rock mechanics effects. A solution to overcome this problem is to adopt in situ stresses in conjunction with a failure criterion to end up with a deterministic model that calculates collapse pressure. However, the uncertainty in input parameters can make this model misleading and useless. In this paper, a new probabilistic wellbore stability model is presented to predict the critical drilling fluid pressure before the onset of a wellbore collapse. The model runs Monte Carlo simulation to capture the effects of uncertainty in in situ stresses, drilling trajectories, and rock properties. The developed model was applied to different in situ stress regimes: normal faulting, strike slip, and reverse faulting. Sensitivity analysis was applied to all carried out simulations and found that well trajectories have the biggest impact factor in wellbore instability followed by rock properties. The developed model improves risk management of wellbore stability. It helps petroleum engineers and field planners to make right decisions during drilling and fields’ development.

Research on Wellbore Stability in Formation with Anisotropic Strength

2013 ◽  
Vol 765-767 ◽  
pp. 3151-3157
Author(s):  
Hui Zhang ◽  
Fang Jun Ou ◽  
Guo Qing Yin ◽  
Jing Bing Yi ◽  
Fang Yuan ◽  
...  
Keyword(s):  
Pore Pressure ◽  
Drilling Fluid ◽  
Wellbore Stability ◽  
Rock Body ◽  
Collapse Pressure ◽  
Wellbore Instability ◽  
Transversely Isotropic Rock ◽  
Fracture Development ◽  
Anisotropic Formation ◽  
The Impact

As most of sedimentary rocks are anisotropic, it is significant to research the impact of the anisotropy of strength on wellbore stability in drilling engineering. Particularly, in the Kuqa piedmont exploration area, the anisotropy of strength caused by various jointed surfaces, fracture surfaces and fault planes in formation cause the formation of several groups of weak low-intensity planes traversing borehole . These weak planes will become failure earlier than the rock body in the context of strong stress and high pore pressure, causing chipping, breakouts and sticking. If fractures have good permeability and drilling fluid column pressure is greater than pore pressure, loss may occur. The loss pressure would not be controlled by fracturing pressure and horizontal minimum principal stress, but it depends on the relationship between fracture occurrence and triaxial stress state. In the event of loss, the drilling fluid will flow into these weak structural planes, causing the decrease of friction between rocks and increase of wellbore instability. As a result, for strongly anisotropic formation, the collapse pressure and leakage pressure of weak planes are key factors for evaluating well drilling stability. In this study, according to the stability evaluation on the transversely isotropic rock mechanics in Keshen zone of Kuqa piedmont, the impacts of fracture development on wellbore instability is analyzed; relevant suggestions on engineering geology for the special pressure window in strong anisotropic formation are also put forward.

scholarly journals Application of Thermal Resistant Gemini Surfactants in Highly Thixotropic Water-in-oil Drilling Fluid System

2019 ◽  
Vol 17 (1) ◽  
pp. 1435-1441
Author(s):  
Yonggui Liu ◽  
Yang Zhang ◽  
Jing Yan ◽  
Tao Song ◽  
Yongjun Xu
Keyword(s):  
Gemini Surfactants ◽  
Drilling Fluid ◽  
Drilling Fluids ◽  
Excellent Thermal Stability ◽  
Oil Drilling ◽  
Low Viscosity ◽  
Emulsion Drops ◽  
Oil Emulsions ◽  
Building Capability ◽  
Liquid Precipitation

AbstractTraditional water-in-oil drilling fluids are limited by their shear thinning behavior. In this article, we propose the synthesis of a thermal resistant quaternary ammonium salt gemini surfactant DQGE-I. This surfactant was synthesized using monomers such as N,N-dimethyl-1,3-propanediamine, organic acids and epichlorohydrin, as well as blocking groups such as N-vinylpyrrolidone (NVP). The prepared surfactant exhibited various advantages over traditional surfactants, including excellent thermal stability, good emulsifying and wetting capability. The use of these surfactants was shown to improve the compactness of emulsifier molecules at the oil/water interface, as well as the overall emulsificaiton effect. Laboratory studies revealed that water-in-oil emulsions prepared using DQGE-I showed high emulsion breaking voltage, low liquid precipitation and small and uniformly distributed emulsion drops. Highly thixotropic water-in-oil drilling fluids based on DQGE-I showed low viscosity, high shear rate and thermal tolerance up to 260oC. Additionally, the proposed fluid was applied in 16 wells (including WS1-H2, GS3 and XS1-H8) in the Daqing Oilfield. Testing showed that DQGE-1 exhibited excellent rheological behavior and wall-building capability. The emulsion breaking voltage exceeded 1500 V, and the yield point/ plastic viscosity ratio exceeded 0.4. The use of this surfactant can help to solve problems such as high formation temperature and poor well wall stability.

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