scholarly journals Experimental approach for assessing filter-cake removability derived from reservoir drill-in fluids

2021 ◽  
Vol 11 (11) ◽  
pp. 4029-4045
Author(s):  
Asad Elmgerbi ◽  
Gerhard Thonhauser ◽  
Alexander Fine ◽  
Rafael E. Hincapie ◽  
Ante Borovina

AbstractPredicting formation damage in cased-hole and open-hole completion wells is of high importance. This is especially relevant when the damage is caused by reservoir drill-in fluids hence being well-bore induced. Cake filter removal has proven to be a good approach to estimate induced damage and to evaluate drill-in fluids’ performance. We present an experimental methodology to evaluate filter cake removal, which could be achieved during the well's initial production. An improved experimental setup, to the ones presented in literature, has been developed to enhance data quality. A twofold approach was used for setup design, and first, it can be integrated with devices used to evaluate the static/dynamic filter-cake. Second, it can be used to simulate more realistic cases (field related) by adjusting the experiment parameters. Hence, to replicate the expected drawdown pressure as well as the corresponding flow rate of the studied reservoir. Three key indicators directly related to filter-cake removal were used as evaluators in this work. Lift-off pressure, internal and external filter cakes removal efficiency. Three reservoir fluid systems were studied, two polymer-based and one potassium carbonate. Results show that pressure required to initiate the collapsing process of the filter cake is not significant. Polymer-based drilling fluids showed better performance in terms of external and internal filter cake cleaning efficiency comparing to potassium carbonate. Moreover, we observed that filtrate volume has no clear relation with the degree of residual damage.

2019 ◽  
Vol 141 (10) ◽  
Author(s):  
Mohamed Mahmoud

The well clean-up process involves the removal of impermeable filter cake from the formation face. This process is essential to allow the formation fluids to flow from the reservoir to the wellbore. Different types of drilling fluids such as oil- and water-based drilling fluids are used to drill oil and gas wells. These drilling fluids are weighted with different weighting materials such as bentonite, calcium carbonate, and barite. The filter cake that forms on the formation face consists mainly of the drilling fluid weighting materials (around 90%), and the rest is other additives such as polymers or oil in the case of oil-base drilling fluids. The process of filter cake removal is very complicated because it involves more than one stage due to the compatibility issues of the fluids used to remove the filter cake. Different formulations were used to remove different types of filter cake, but the problem with these methods is the removal efficiency or the compatibility. In this paper, a new method was developed to remove different types of filter cakes and to clean-up oil and gas wells after drilling operations. Thermochemical fluids that consist of two inert salts when mixed together will generate very high pressure and high temperature in addition to hot water and hot nitrogen. These fluids are sodium nitrate and ammonium chloride. The filter cake was formed using barite and calcite water- and oil-based drilling fluids at high pressure and high temperature. The removal process started by injecting 500 ml of the two salts and left for different time periods from 6 to 24 h. The results of this study showed that the newly developed method of thermochemical removed the filter cake after 6 h with a removal efficiency of 89 wt% for the barite filter cake in the water-based drilling fluid. The mechanisms of removal using the combined solution of thermochemical fluid and ethylenediamine tetra-acetic acid (EDTA) chelating agent were explained by the generation of a strong pressure pulse that disturbed the filter cake and the generation of the high temperature that enhanced the barite dissolution and polymer degradation. This solution for filter cake removal works for reservoir temperatures greater than 100 °C.


Author(s):  
Tianshou Ma ◽  
Nian Peng ◽  
Ping Chen ◽  
Yang Liu

Supercharging in the vicinity of a borehole is an important factor that affects formation damage and drilling safety, and the filter cake growth process has a significant impact on supercharging in the vicinity of the borehole. However, existing models that predict pore pressure distribution overlook dynamic filter cake growth. Thus, an analytical supercharging model was developed that considers time-dependent filter cake effects, and this model was verified using a two-dimensional numerical model. The influences of filter cake, formation, and filtrate properties on supercharging were investigated systematically. The results indicate that time-dependent filter cake effects have significant influence on supercharging. Supercharging increases in the early stage but decreases over time because of the dynamic growth of filter cake, and the supercharging magnitude decreases along the radial direction. Because of filter cake growth, the magnitude of supercharging falls quickly across the filter cake, and the decreased magnitude of pore pressure caused by the filter cake increases. Supercharging in low-permeability formations is more obvious and the faster rate of filter cake growth, a lower filtrate viscosity and faster reduction rate of filter cake permeability can help to weaken supercharging. The order of importance of influencing factors on supercharging is overbalance pressure > formation permeability > formation porosity ≈ filtrate viscosity > filter cake permeability attenuation coefficient > initial filter cake permeability control ratio > filter cake growth coefficient > filter cake porosity. To alleviate supercharging in the vicinity of the borehole, adopting drilling fluids that allow a filter cake to form quickly, optimizing drilling fluid with a lower filtrate viscosity, keeping a smaller overbalance pressure, and precise operation at the rig site are suggested for low-permeability formations during drilling.


Author(s):  
Osama Siddig ◽  
Ahmed Abdulhamid Mahmoud ◽  
Salaheldin Elkatatny

AbstractTreatment of the filter cake layer after drilling is essential for better cement integrity and to retain the original reservoir permeability. Compared to water-based filter cake, oil-based mud filter cake removal is more sophisticated as oil encloses the filter cake’s particles. Therefore, oil-based mud clean-up requires wettability alteration additives (mutual solvents and/or surfactants) for permitting acid/filter cake reaction. With an appropriate acid, microemulsions were reported to be very efficient in cleaning oil-based filter cakes, due to their low interfacial tension and high acid solubility. The objective of this paper is to provide an overview of the different techniques and treatment solutions utilized in oil-based filter cake clean-up. Furthermore, a synopsis of the various treatments for drilling fluids densified with different weighting materials is presented. Subsequently, the research limitations and opportunities have been highlighted for future work. In the light of the review that has been presented in this paper, it's recommended to conduct further investigation on some areas related to filter cake removal. The removal of filter cake formed from weighting materials other than barite, calcium carbonate, ilmenite, and manganese tetroxide needs to be investigated thoroughly. Additionally, the overall efficiency of oil-based mud removal needs to be studied under wide ranges of temperature, salinity, and pH. The utilization of surfactant-free microemulsions in filter cake treatment could also be investigated.


2020 ◽  
Vol 12 (8) ◽  
pp. 3427
Author(s):  
Osama Siddig ◽  
Saad Al-Afnan ◽  
Salaheldin Elkatatny ◽  
Mohamed Bahgat

An impermeable layer “filter cake” usually forms during the overbalanced drilling technique. Even though it helps in protecting the formation from a further invasion of drilling fluids, the removal of this layer is essential for a proper cement job and to avoid any reduction in wellbore deliverability. The design of the removal process is complicated and depends on the filter cake composition and homogeneity. This paper presents an experimental evaluation on the usage of a novel cake washer (NCW) in the removal of a filter cake formed by an invert emulsion oil-based drilling fluid that contains calcium carbonate as a weighting material while drilling a horizontal reservoir. The proposed NCW is a mixture of organic acid, mutual solvent and nonionic surfactant. It is designed to enable restored wellbore permeability for a sustainable production. Since the filter cake mainly consists of the weighting material, the solubility of calcium carbonate in NCW at different ranges of temperature, duration and concentration was investigated. An actual casing joint was used to test the corrosion possibility of the treating solution. High-pressure and high-temperature (HPHT) filtration tests on ceramic discs and Berea sandstone core samples were conducted to measure the efficiency of the filter cake removal and the retained permeability. Ethylene glycol mono butyl ether (EGMBE) was used as a mutual solvent and the solubility was higher compared to when the mutual solvent was not used in the washer formulation. A significant increase in calcium carbonate dissolution with time was observed for a duration of 24 h. The solubility was found to be proportional to the concentration of NCW with optimum results of 99% removal at a temperature of around 212 °F. At those conditions, no major corrosion problems were detected. Permeability of the core retained its pristine value after the treatment.


2020 ◽  
Vol 143 (2) ◽  
Author(s):  
Mobeen Murtaza ◽  
Zeeshan Tariq ◽  
Mohamed Mahmoud ◽  
Muhammad Shahzad Kamal ◽  
Dhafer Al-Shehri

Abstract Different additives such as barite, calcium carbonate, hematite, and ilmenite having high-density and fine solid materials are used to increase the density of drilling fluids. However, some of the weighting additives can cause some serious drilling problems such as barite (particle settling, formation damage, erosion, and insoluble filter cake). In this study and for the first time, anhydrite (calcium sulfate) is used as a weighting additive in the drilling fluids. Several laboratory experiments such as density, rheology, fluid loss, resistivity, and pH were carried out to assess the performance of calcium sulfate as a weighting additive in the drilling fluids. The performance of calcium sulfate as a weighting additive was compared with the commonly used weight enhancing additive calcium carbonate. The results showed that calcium sulfate has higher solubility than calcium carbonate. The fluid loss test showed that both additives lost the same volume of fluid and created the same thickness of filter cake; however, the solubility of calcium sulfate-based filter cake with organic and inorganic acids was higher compared with other weighting materials. Calcium sulfate-based filter cake was completely dissolved using a new formulation that consists of glutamic-diacetic acid (GLDA) chelating agent and potassium carbonate as a convertor. The removal efficiency after 10 h reached 100% in 20 wt% GLDA and 10 wt% potassium carbonate solution at 100 °C.


2021 ◽  
Author(s):  
Charlotte Eliasson ◽  
Ove Braadland ◽  
Håvard Kaarigstad ◽  
Anne-Mette Mathisen ◽  
Zalpato Ibragimova ◽  
...  

Abstract For the Johan Castberg field development project, injector wells are important for achieving high production and overall high recovery factors. Injectivity has become more important due to limitations in injection pressures and required control of fracture growth. Securing injectivity has been identified as one of the project’s main risks, making drill-in fluid and breaker fluid system qualification a vital parameter for success. Operational procedures and completion design also affect the effectiveness of breaker fluid placement and, thus, the overall injectivity of the well. In this paper, we present a cross-disciplinary systematic approach for the reservoir drill-in fluid and breaker fluid qualification to ensure injectivity in these wells. Two wells were selected for covering the expected pressure and temperature range of the field in an environmentally sensitive area. Two independent fluid systems were designed, where the bridging material consisted of either sized salt particles or calcium carbonate particles. The open hole completion design has been optimized for an effective breaker fluid placement, using a modified gravel pack system with a wash pipe. The displacement sequence has been optimized for effective deployment. An extensive laboratory test matrix for both the reservoir drilling fluid (RDF) and breaker fluid system was established, including thorough analysis of the interaction between the deposited filter cake and the breaker fluid system. The RDF and breaker fluid formulation optimization was performed whilst keeping in mind the operational requirements and the well’s future injectivity The presented results show successful qualification of two independent fluid and breaker fluid systems where filter cake breakthrough is achieved within the desired time frame. The fluid systems in combination with the lower completion design and operational procedures ensure maximal reservoir exposure of the breaker fluid solution and enable rapid deterioration of the filter cake.


2007 ◽  
Author(s):  
Mathew M. Samuel ◽  
Abdul Hameed Ahmad Mohsen ◽  
Aziz Ejan ◽  
Matthew Alexander Law ◽  
Chao Wei Wrong ◽  
...  

2021 ◽  
Author(s):  
Vikrant Wagle ◽  
Abdullah Yami ◽  
Michael Onoriode ◽  
Jacques Butcher ◽  
Nivika Gupta

Abstract The present paper describes the results of the formulation of an acid-soluble low ECD organoclay-free invert emulsion drilling fluid formulated with acid soluble manganese tetroxide and a specially designed bridging package. The paper also presents a short summary of field applications to date. The novel, non-damaging fluid has superior rheology resulting in lower ECD, excellent suspension properties for effective hole cleaning and barite-sag resistance while also reducing the risk of stuck pipe in high over balance applications. 95pcf high performance invert emulsion fluid (HPIEF) was formulated using an engineered bridging package comprising of acid-soluble bridging agents and an acid-soluble weighting agent viz. manganese tetroxide. The paper describes the filtration and rheological properties of the HPIEF after hot rolling at 300oF. Different tests such as contamination testing, sag-factor analysis, high temperature-high pressure rheology measurements and filter-cake breaking studies at 300oF were performed on the HPIEF. The 95pcf fluid was also subjected to particle plugging experiments to determine the invasion characteristics and the non-damaging nature of the fluids. The 95pcf HPIEF exhibited optimal filtration properties at high overbalance conditions. The low PV values and rheological profile support low ECDs while drilling. The static aging tests performed on the 95pcf HPIEF resulted in a sag factor of less than 0.53, qualifying the inherent stability for expected downhole conditions. The HPIEF demonstrated resilience to contamination testing with negligible change in properties. Filter-cake breaking experiments performed using a specially designed breaker fluid system gave high filter-cake breaking efficiency. Return permeability studies were performed with the HPIEF against synthetic core material, results of which confirmed the non-damaging design of the fluid. The paper thus demonstrates the superior performance of the HPIEF in achieving the desired lab and field performance.


Author(s):  
E.A. Flik ◽  
◽  
Y.E. Kolodyazhnaya

The article assesses the environmental safety of drilling fluids that are currently widely used in the oil and gas industry. It shows active development of water-based drilling fluid systems using xanthan biopolymer.


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