scholarly journals Borehole Stability in Shale Formation: Modeling the Effects of Molecular Weight and Concentration of Polymers in the Drilling Fluids Formulation

2014 ◽  
Vol 5 (1) ◽  
pp. 260-270
Author(s):  
Khoshniyat A ◽  
Shojaei M. ◽  
Jarahian K. ◽  
Mirali M. ◽  
Ghorashi S. ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Reflection Coefficient ◽  
Drilling Fluid ◽  
Exchange Capacity ◽  
Oil Field ◽  
Wellbore Stability ◽  
Drilling Fluids ◽  
Drilling Process ◽  
Borehole Stability ◽  
Shale Formation

A new experimental model was developed to predict the role of special polymeric additives, in the drilling fluid formulation, on the wellbore stability in shale formation. The shale formation was regarded as a non-ideal membrane and the effects of various characteristics of the added polymers were studied on the membrane reflection coefficient. The model was applied to unique field data from the oil field in south of Iran, including clay structure, cation exchange capacity (CEC), density and porosity of the shale. The results, using various polyglycols and polyacrylamides as the polymeric additive, showed that the structure of the polymeric chains e.g. type and content of ionic segments had significant effect on their adsorption mechanism and its strength.  It was concluded that increasing the molecular weight of the polymer chains decreased the rate and amount of the adsorption due to the increasing of the entanglements between the chains which in turn limited their mobility. So, adsorption of the polymeric material on the shale had significant impress on its performance as a membrane by increasing the shale reflection coefficient enhancing its stability during drilling process. Finally, the developed model results were in good agreement by experimental test results which was done in a specific shale stability set up.

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.

Mechanical-Thermal-Chemical Coupled Research of Wellbore Stability in Jabung Oil Field, Indonesia

2011 ◽  
Vol 402 ◽  
pp. 709-714 ◽  
Author(s):  
Pei Yang ◽  
Mian Chen ◽  
Yan Jin ◽  
Bing Hou ◽  
Kang Qiu ◽  
...  
Keyword(s):  
Stress Distribution ◽  
Drilling Fluid ◽  
Great Influence ◽  
Chemical Properties ◽  
Oil Field ◽  
Wellbore Stability ◽  
Additional Stress ◽  
Borehole Stability ◽  
Well Trajectory ◽  
The Impact

The Jabung oilfield in Indonesia is characterized by complex geological structural movement, large tectonic stress and high temperature gradient. Accidents such as borehole collapse and sticking were frequently encountered when drilling shale formations, which often result in serious damage. In this paper, a series of experiments were conducted to evaluate the performance of shale in drilling fluid, including linear expansion rate evaluation tests and rolling recovery evaluation tests. Also X-ray diffraction was used to analyze the mineral composition of shale. The mechanical parameters of shale were obtained through statistical analysis. By using ABAQUS software, the temperature difference induced by thermal stress distribution was analyzed. After that, the borehole stress distribution was determined by coupling the additional stress with in-situ stress. Finally, based on borehole stability mechanical models, the effects of well trajectory on borehole stability were analyzed. We found that the chemical properties of drilling fluid, wellbore trajectory and temperature has a great influence on wellbore stability, and the impact of temperature changes and of well trajectory are the largest factor.

The Research of the Oil Base Drilling Fluid Hard Brittle Shale Sidewall Instability Mechanism

2014 ◽  
Vol 513-517 ◽  
pp. 309-313 ◽  
Author(s):  
Guang Feng Zhen ◽  
Go Lin Jing ◽  
Wei Jie Hu ◽  
Bai Sun Liao
Keyword(s):  
Drilling Fluid ◽  
Continuous Production ◽  
Exchange Capacity ◽  
Wellbore Stability ◽  
Instability Mechanism ◽  
X Ray Diffraction ◽  
X Ray ◽  
Mechanism Research ◽  
Shale Formation ◽  
Temperature Time

With the continuous production of the well development, sidewall instability phenomenon has become increasingly serious, mostly occurs in the shale formation, benefit for oilfield produced great harm. Water-based drilling fluid sidewall instability mechanism has been basically clear, the oil-base drilling fluid influence on sidewall stability is not yet concrete. So this paper mainly for oil-based drilling fluid hard brittle shale sidewall instability mechanism research. This article first from the perspective of chemistry, the hard brittle shale borehole wall instability is studied, the experiment tested respectively by the white oil and water treatment of hard brittle shale of cation exchange capacity (CEC) value, so as to analyze the same and the hydration of clay mineral equivalent after processing samples, through analysis of the temperature, time, media's impact on hard brittle shale wellbore stability. Secondly, from the Angle of mechanics, stress and mechanical properties of mud shale formation is analyzed, and the minimum drilling fluid density model, gives a variety of analysis and calculation formula. In addition, this paper adopted the X ray diffraction (XRD)

scholarly journals Studying the Wellbore Stability Enhancement Mechanism during Drilling through Fractured Argillites

2020 ◽  
Vol 20 (3) ◽  
pp. 231-241
Author(s):  
Mariia V. Nutskova ◽  
◽  
Inna V. Chudinova ◽  
Aleksandr N. Sobolev ◽  
◽  
...  
Keyword(s):  
Potassium Chloride ◽  
Drilling Fluid ◽  
Experimental Studies ◽  
Wellbore Stability ◽  
Drilling Fluids ◽  
Drilling Process ◽  
Sample Length ◽  
Construction Costs ◽  
Well Abandonment ◽  
A Minor

The paper presents the relevance of enhancing wellbore stability by developing and applying efficient drilling fluid compositions for well constructions in fractured argillite. In the process of well constructions, there comes a range of complications associated with instability of rocks forming borehole walls, which sometimes results in lower penetration rates, higher construction costs and well abandonment. Often, drilling problems occur at drilling through mudrocks that account for up to 70 % of field sections. When using water-base drilling fluids, the mudrock swelling due to the contact with the fluid dispersion medium adversely affects the drilling process and can significantly increase well construction costs. The accumulation of wellbore cavings inhibits well circulation, causes landing of drilling tools and may result in tool sticking. An analysis of drilling problems in fractured argillite is presented; the mechanisms affecting open hole stability in the fractured argillite deposits are shown. The use of potassium chloride is recommended to enhance the stability of argillite-formed borehole walls. The results are supported by experimental studies using the Chenevert method, as well as fracture propping tests. When the argillite sample was placed in potassium chloride (KCl) solution, there was a minor fracture expansion and propagation over the entire sample length, which is a positive result. To enhance wellbore stability, further study approaches are proposed: upgrading mud by adding inhibiting compounds, such as salt solutions in combination with high-molecular polymer compositions.

Integrated Multidisciplinary Solution for Improving Wellbore Stability and Drilling Efficiency in a Conglomerate Reservoir, a Case Study from North-West China

2021 ◽  
Author(s):  
Yalin Li ◽  
Jiangang Shi ◽  
Fang Zhang ◽  
Shanshan Wang ◽  
David Wiprut ◽  
...  
Keyword(s):  
Multidisciplinary Approach ◽  
Drilling Fluid ◽  
Junggar Basin ◽  
Wellbore Stability ◽  
Drilling Fluids ◽  
Drilling Process ◽  
Rotary Drilling ◽  
North West ◽  
Field Development ◽  
Weight Window

Abstract Drilling long horizontal development wells in a conglomerate reservoir with strong heterogeneity has been challenging in the Junggar Basin, onshore China. To develop the fields economically, rapid and safe drilling with minimal non-productive time (NPT) is required. However, various drilling problems such as stuck pipe, mud losses have been experienced in the build-up section while the horizontal conglomerate section experienced an extremely low rate of penetration (ROP). To overcome the drilling challenges, a thorough understanding of the subsurface characteristics of the formations is critical to develop effective engineering solutions. To improve drilling efficiency, an integrated multidisciplinary approach was applied to derive an effective drilling solution. Drilling experiences from offset wells were reviewed systematically to identify the possible reasons that have caused the drilling problems. This diagnostic approach helped to identify appropriate drilling solutions for mitigating the different drilling risks. Detailed geomechanical models were also constructed to understand the stress state and rock mechanical properties of the conglomerate reservoir and the overburden formations so that proper mud weights can be defined for each section to control both wellbore collapse and mud losses. Mud weight recommendations and failure mechanism diagnosis also provided the basis for drilling fluids designs. Additionally, in order to achieve a better hole quality as well as increase the reservoir contact and ROP, advanced rotary drilling systems were also used with real time monitoring. The latter enabled the tracking of rock property and ECD changes as well as other drilling parameters during the drilling process. This integrated solution was applied in the drilling of several horizontal wells. One typical case is presented in this paper. In this well, the risk of hole instability was very high because the well was targeting a deeper formation with a few shaly intervals in the build-up section which are known to cause serious wellbore stability problems. The safe mud weight window inferred from geomechanical analyses appears to be very narrow, particularly at the casing shoe where the mud weight required to control borehole collapse is very close or even higher than the fracture gradient. To help with drilling the well cost-effectively, drilling fluid was designed to perform three (3) critical functions - 1) maintaining wellbore stability, 2) increasing ROP and 3) broadening the mud weight window to minimize mud losses. The successful drilling of this well broke the drilling record in the same block. The integrated multidisciplinary approach successfully reduced the occurrence of borehole instability related problems and NPT in the study well. Following the same methodology, the drilling efficiency will improve with more experience and understanding obtained from continuous drilling. This continuous learning process will be the key aspect of this project, eventually contributing to the success of the field development.

Anti-Collapse Drilling Fluids for the Cretaceous Scientific Drilling in Songliao Basin, China: A Case Study

2012 ◽  
Vol 170-173 ◽  
pp. 1196-1201
Author(s):  
Ji Hua Cai ◽  
Xiao Ming Wu ◽  
Sui Gu
Keyword(s):  
Drilling Fluid ◽  
Songliao Basin ◽  
Wellbore Stability ◽  
Drilling Fluids ◽  
Shale Formations ◽  
Scientific Drilling ◽  
Fluid Systems ◽  
Managed Pressure Drilling ◽  
Shale Formation

CCSD-SK1 well was the first Cretaceous scientific drilling well in the world, locating in Songliao basin, Northeast China. It included main well (also called north well) and south well. This paper introduced the anti-collapse drilling fluid technology in main well where the desired continuous coring section was from 164.77 m to 1792.00 m. Continuous technical barriers challenged the intelligence of drilling engineers of this project. First, preserving the wellbore stability was the most critical aspect of continuous core drilling. From top to bottom, the unconsolidated sandstone in the Quaternary super stratum, the water sensitive shale in the Sifangtai group and upper stratum of the Nenjiang group, and the brittle shale of under stratum of the Nenjiang group increased the difficulty of anti-collapse drilling fluid technology. Water invasion into the shale formation often weakens the wellbore and causes problems such as wellbore collapse, shale destabilization and stuck pipe. Fluids should be designed to mitigate these shale problems. Secondly, the openhole strategy imposed the difficulty of maintaining wellbore stability in the second open process (from 245.00 m to the bottom). Finally, the total expense of the well was only one fifth of south well, which was drilled by an oilfield drilling contractor. To overcome these technical challenges, not only different drilling fluid systems such as PAM drilling fluid, DFD-LG-CMC drilling fluid and DFD-NH4HPAN-SAKH drilling fluid were adopted separately, but also technology of feasible viscosity and managed pressure drilling were used. A total of 395 trips had been run in this Cretaceous scientific drilling well and no accidents even dangerous cases occurred. The experience of CCSD-SK1 (main well) explored a successful way of employing economic drilling fluid to preceding similar scientific drilling projects in similar shale formations.

Organophilic Clay-Based Drilling Fluids for Mitigation of Unconventional Shale Reservoirs Instability and Formation Damage

2019 ◽  
Vol 141 (9) ◽  
Author(s):  
Hafiz Mudaser Ahmad ◽  
Muhammad Shahzad Kamal ◽  
Mohamed Mahmoud ◽  
S.M. Shakil Hussain ◽  
Mohamed Abouelresh ◽  
...  
Keyword(s):  
Molecular Weight ◽  
High Molecular Weight ◽  
Gemini Surfactant ◽  
Drilling Fluid ◽  
Formation Damage ◽  
Drilling Fluids ◽  
Borehole Stability ◽  
High Molecular Weight Polymer ◽  
Molecular Weight Polymer ◽  
Organophilic Clay

High-performance drilling fluid was designed for unconventional reservoirs to minimize the formation damage and borehole instability using organophilic clay treated with trimethyloctylammonium bromide, novel in-house synthesized gemini surfactant, and a high-molecular weight polymer. This gemini surfactant has not been reported in the literature for drilling fluid applications. The performance of designed drilling fluid was evaluated and compared with the base drilling fluid (4 w/v.% bentonite dispersion water). Shale dispersion, linear swelling, filtration, and rheological experiments were performed to investigate the effect of drilling fluids on borehole stability and formation damage. The combined use of organophilic clay and surfactant in the drilling fluid formulation reduced the shale dispersion up to 89%. The linear swelling experiment of shale sample shows 10% swelling of the core in the modified drilling fluid while in base fluid 13% swelling of shale was observed. It was found that modified drilling fluid interactions with shale were greatly reduced using a surfactant and associative polymer in the drilling fluid formulation. Rheological properties of drilling fluids were stable, and filtration characteristics showed that the filtrate volume was within the acceptable limit. The designed drilling fluid made a thin and impermeable filter cake that prevents the invasion of drilling fluid into the formation. This study opens a new direction to reduce the formation damage and borehole instability using organophilic clay, surfactant and high-molecular weight additive in water-based drilling fluid.

Inhibiting Calcium Chloride Heavy Brines to be Used as Drilling Fluids: Hurdles Encountered in Treatment, Application, Corrosion Mitigation, Solubility, and Foaming Tendencies for Drilling Sites in Canada

2021 ◽  
Author(s):  
Thenuka M. Ariyaratna ◽  
Nihal U. Obeyesekere ◽  
Tharindu S. Jayaneththi ◽  
Jonathan J. Wylde
Keyword(s):  
Corrosion Inhibitor ◽  
Corrosion Inhibitors ◽  
Drilling Fluid ◽  
Solvent System ◽  
Test Fluid ◽  
Drilling Fluids ◽  
Drilling Process ◽  
Drill Cuttings ◽  
Well Completion ◽  
Completion Fluids

Abstract A need for more economic drilling fluids has been addressed by repurposing heavy brines typically used as completion fluids. Heavy brine corrosion inhibitors have been designed for stagnant systems. Drilling fluids are subjected to both heavy agitation and aeration through recirculation systems and atmospheric exposure during the various stages of the drilling process. This paper documents the development of heavy brine corrosion inhibitors to meet these additional drilling fluid requirements. Multiple system scenarios were presented requiring a methodical evaluation of corrosion inhibitor specifications while still maintaining performance. Due to the high density of heavy brine, traditional methods of controlling foaming were not feasible or effective. Additional product characteristics had to be modified to allow for the open mud pits where employees would be working, higher temperatures, contamination from drill cuttings, and product efficacy reduction due to absorption from solids. The product should not have any odor, should have a high flash point, and mitigate corrosion in the presence of drill cuttings, oxygen, and sour gases. Significant laboratory development and testing were done in order to develop corrosion inhibitors for use in heavy brines based on system conditions associated with completion fluids. The application of heavy brine as a drilling fluid posed new challenges involving foam control, solubility, product stability, odor control, and efficacy when mixed with drill cuttings. The key to heavy brine corrosion inhibitor efficacy is solubility in a supersaturated system. The solvent packages developed to be utilized in such environments were highly sensitive and optimized for stagnant and sealed systems. Laboratory testing was conducted utilizing rotating cylinder electrode tests with drill cuttings added to the test fluid. Product components that were found to have strong odors or low flash points were removed or replaced. Extensive foaming evaluations of multiple components helped identify problematic chemistries. Standard defoamers failed to control foaming but the combination of a unique solvent system helped to minimize foaming. The evaluations were able to minimize foaming and yield a low odor product that was suitable for open mud pits and high temperatures without compromising product efficacy. The methodology developed to transition heavy brine corrosion inhibitors from well completion applications to drilling fluid applications proved to be more complex than initially considered. This paper documents the philosophy of this transitioning and the hurdles that were overcome to ensure the final product met the unique system guidelines. The novel use of heavy brines as drilling fluids has created a need for novel chemistries to inhibit corrosion in a new application.

Keeping Shale Formation Stability by Optimizing Drilling Fluids, in Yangta Oil Field, Western China

2009 ◽  
Author(s):  
Xiangjun Liu ◽  
Pinya Luo ◽  
Hong Liu ◽  
DaChuan Liang ◽  
Faqian Luo
Keyword(s):  
Oil Field ◽  
Western China ◽  
Drilling Fluids ◽  
Shale Formation
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