Loss Circulation Materials Research Articles

Shape memory polymers as new advanced loss circulation materials for drilling applications

Shape memory polymers as new advanced loss circulation materials for drilling applications

Magnesium Oxychloride and Magnesium Oxysulfate Cements as Temporary Plugging Agents in Geothermal Drilling.

The development and utilization of geothermal resources are effective ways to alleviate the current haze situation, adjust the energy structure, and achieve energy conservation and emission reduction. Geothermal formations typically contain extensive fracture networks, with fracture openings. These fracture networks can result in substantial losses of the drilling fluid and increased costs for geothermal drilling. Temporary plugging cements are used to solve the problem of lost circulation due to their high strength and high acid solubility. In this paper, two types of temporary plugging materials, magnesium oxysulfate (MOS) cement and magnesium oxychloride (MOC) cement, were prepared. The influence of the plugging agent on the flow field and the force exerted on the solid under the action of the fluid was analyzed using fluid-solid coupling software. The simulation results show that when subjected to a flow rate of 10 m/s, the edge of the cement experiences a significant force, while the stress is not widely transmitted to the middle and rear of the cement. This indicates that the cement has a strong resistance to the fluid flow. The fundamental characteristics of MOC cement and MOS cement, such as compressive strength and setting time, were investigated. The test results show that adjusting the molar ratio of the two types of cements can shorten the setting time by 60% and increase the compressive strength to up to 23 MPa. In addition, the acid solubility of the cement with different ratios of raw materials is above 95%. The plugging performance of these two cements as loss circulation materials was evaluated by using a physical simulation device. The pressure bearing capacity of the MOC cement with different MgO/MgCl2·6H2O/H2O molar ratios ranged between 13.4 and 23.6 MPa. The maximum bearing capacity of the MOS cement can reach up to 18.6 MPa. The results showed that both cements possess excellent plugging and pressure bearing capacity.

The Development and Evaluation of Novel Self-Degrading Loss-Circulation Material for Ultra-Deepwater Drilling in South China Sea

Focusing on the problem of drilling fluid loss circulation due to fractured granite formation in ultra-deepwater drilling in the research area, a novel self-degrading loss-circulation material is developed with polymer resin as the core material, according to the principles of loss-circulation prevention and reservoir and environmental protection. The relevant properties of the novel self-degrading loss-circulation material are evaluated by using tests or experiments. The pressure-bearing properties are evaluated by using a sealing capability test; the self-degrading properties are evaluated by using a self-degrading performance test; the pressure-bearing capability and reservoir protection properties are tested by measuring pressure sealing and gas permeability. The results of the tests and experiments show that the grinding rate of the loss-circulation material is less than 6% under 25 MPa, indicating that the novel loss-circulation material is of high compressive strength. The degradation process of the novel self-degrading loss-circulation material can be accelerated by increasing temperature and pH, and the degradation of the self-degradable polymer composite can be accomplished within 5 days under 95 °C and pH = 14. After self-degrading, the permeability recovery values of the highly permeable reservoir and the fractured reservoir are more than 96.9% and 99.15%, respectively, which indicates outstanding reservoir protection capability. Therefore, the novel self-degrading loss-circulation material has excellent temporary plugging and reservoir protection performance and can be used for plugging while drilling in ultra-deepwater drilling.

Development and application of guar gum crosslinked gel with adjustable gelation time for total loss treatment

To remediate the problem of severe or total losses, and meet the requirements of borehole plugging and pumping at different well depths, a novel crosslinked polymer gel (named HPG/Zr gel) with controlled gelation time and high gel strength was developed as loss circulation material, which mainly comprised hydroxypropyl guar gum, zirconium compound and triethanolamine. The influence of hydroxypropyl guar gum concentration, zirconium compound concentration, triethanolamine concentration and temperature on the gelation time of HPG/Zr gel was evaluated. In addition, the performance of HPG/Zr gel was investigated in terms of temperature resistance and shear resistance property, plugging ability and supporting cement slurry ability. According to the results, HPG/Zr gel can form a viscoelastic body with a network structure, and its gelation time can be practically adjustable. The results of the plugging experiment at different temperatures, pressures and pore sizes of quartz sand revealed that HPG/Zr gel could effectively plug sand pores at 150°C, and its pressure-bearing capacity can be up to 5 MPa. Employing its flow resistance and ability of supporting cement slurry, HPG/Zr gel was successfully applied in two geological boreholes by combining with cement slurry. Overall, the results of laboratory research and field tests indicate that HPG/Zr gel is useful for mitigating the lost circulation, and it is of huge importance to engineering applications.

Eco-Friendly Bridging Material: Experimental Characterization of Eggshells as an Affordable Natural Waste Non-Damaging Lost Circulation Material to Reduce Drilling Fluid Cost in Reservoir Drill-In-Fluid System

Lost circulation nowadays became one of the major problems in many drilling operations worldwide. This problem is complicated for it can significantly cause non-productive time during drilling operations. This research aims to study eggshells as a LCM and to provide further insight about the reliability and cost analysis of eggshells as a potential drilling fluid additive. Moreover, the research successfully identified the usage of an abundant natural waste, i.e. eggshells, as an environmentally friendly fluid additive. This research also investigated the technical feasibility of the eggshells and also its economics impact on drilling operations. In addition, it is found that the eggshells can also act as a non-damaging LCM for production zone that is more affordable as compared to other natural waste loss circulation materials and current commercially chemical. Series of laboratory tests were conducted such as mud balance for the density test, rheological test using viscometer Fann Vg, filtration loss test with filter press, and also alkalinity (pH) test. An excellent result from filtration loss test i.e. decreased fluid losses and showed great improvement almost same as commercially CaCO3 result in the filter cake thickness. The research proves great potential of the utilization of eggshells as a multi-purpose additive in a drilling fluid. Economic analysis also suggests that it can possibly be implemented and to be further developed for a large-scale field operations. Finally, it is found that using eggshells as LCM can reduce the cost up to 72.2 % cheaper than commercial CaCO3. It is also safe for drilling in the production zone (pay-zone) because of its solubility on acid that it can disappear during the acidizing job. If this paper can be implemented on a wide-range scale it will be very beneficial to reduce other commercial additives usage without losing its reliability.

Performance evaluation of nanosilica derived from agro-waste as lost circulation agent in water-based mud

Seepage or loss of the mix-water from the drilling muds into the porous and permeable formations is a common problem during drilling operation. The drilling mud design requires a good knowledge of sealing integrity and all the factors influencing the mud to bridge through fractures or pore throat of exposed rocks. Loss circulation materials (LCMs) are commonly introduced into the drilling mud to prevent or minimize filtrate loss. This study investigates silica nanoparticle (SNP) derived from rice husk (RH) termed RH-SNP using the wet-milling method as an LCM in water-based mud (WBM). The impact of the RH-SNP in the enhancement of rheology and filtrate loss control properties of WBM was studied. Subsequently, the sealing integrity of the RH-SNP in a 1 mm and 2 mm simulated fracture for 7 min was determined using a stainless-steel slotted filter disk. The performance of the developed RH-SNP was compared with the widely applied nutshell. The synthesized RH-SNP at amount of 2.0 wt% significantly enhanced the yield point and plastic viscosity of the WBM by 75% and 386%, respectively, and minimized the fluid loss of the WBM by 47% at 80 °F. The enhancement is due to the particles ability to spread and interact efficiently with the WBM. With the use of 1 mm and 2 mm simulated fracture for 7 min, the mud loss volume of the base mud reduced by 50%, 66.7%, 86%, and 90% (for 1 mm) and 40%, 65.7%, 77.1%, and 80% (for 2 mm) with the inclusion of 0.5 wt%, 1.0 wt%, 1.5 wt%, and 2.0 wt% of RH-SNP, respectively. Overall, the results showed that RH-SNP enhanced the seal integrity of the drilling mud and was more resistant to deformation compared to the nutshell. The findings of this study can help for better understanding of the application of RH-SNP as a loss circulation agent owing to its superior ability to seal fractured formation compared with the often used nutshell.

Lost circulation mitigation using modified enzyme induced calcite precipitation technique

Circulation loss is a very common and undesirable non-productive time (NPT) event that happens during the oil and gas well drilling operations. Many loss circulation materials (LCM) have been formulated and implemented in the process of gas and oil wells drilling to minimize or mitigate this problem. In-situ calcite precipitation in effective pores can restrict the movement of the water flow between the grains by forming bridges. In this study, different mixes of Enzyme-induced calcite precipitation (EICP) solution are studied and tested in the laboratory to mitigate lost circulation problem. EICP solution is primarily composed of urea, calcium chloride, magnesium chloride, Xanthan Gum, and urease enzyme. Different concentrations and compositions of reagents were tested. The properties of the created precipitates were examined through different techniques such as X-ray diffraction analysis (XRD), scanning electron microscopy (SEM), and thermogravimetric analysis (TGA). The combination that produced the highest amount of thermally stable calcite with a minimal amount of aragonite, along with the highest precipitation efficiency was further selected for lost circulation application. A solution containing 1M Urea, 0.9M CaCl 2 , 0.1M MgCl 2 , 1 g/L Xanthan Gum, and 3 g/L urease was considered as an optimum combination for an EICP process. Lost circulation experiments were carried out in core flooding experiments on a high permeable Indian Limestone sample at room and elevated temperature conditions with the optimum combination of EICP reagents. The permeability of the samples was measured before and after the treatment. Nuclear Magnetic Resonance (NMR) scan was also run before and after the treatment to determine the pore size redistribution. Results showed that the permeability of the samples was reduced by 99%, NMR results showed that the porosity of the samples was also reduced by 20%. • Investigation of the modified enzyme induced calcite precipitation as a lost circulation technique. • Investigation of incorporating magnesium in an EICP process to precipitate dolomite mineral. • Investigation of incorporating Xanthan Gum as a temperature stabilizer for an EICP reaction. • Coreflooding and NMR experiments with optimized EICP solution as a potential lost circulation material. • 99% reduction in permeability achieved with modified EICP process.

Evaluating sealability of blended smart polymer and fiber additive for geothermal drilling with the effect of fracture opening size

Geothermal formations often contain extensive fracture networks. These fracture networks contribute to the significant loss of drilling fluids during geothermal drilling. Multiple loss circulation materials (LCM) such as fiber, granules, and pills have been proposed to tackle this problem but with only limited success. Recent advances in materials science have led to the development of thermoset shape memory polymers (SMP) to address the lost circulation problem. In this paper, we evaluate a thermoset SMP performance in sealing near wellbore fractures of different sizes in geothermal wells. The SMP performance was assessed using granite disks and cylindrical granite cores having fracture sizes of 1000 μm and 3000 μm. A static filtration test was performed using cedar fiber, CaCO3, and SMP. Results showed cedar fiber performed better than the CaCO3., reducing fluid loss by 89% and improving sealing pressure by 200 psi. A novel dynamic testing unit that allows for high-temperature testing under flowing conditions was used in this study. The analysis showed that 3% by weight SMP and fiber blends could bridge and plug the 1000 μm fracture. For a larger fracture of 3000 μm width, there was a need to increase the weight concentration of the SMP to 6% to plug the fracture opening effectively. We showed the influence of key parameters such as the type of LCM, concentration, and particle size distribution in optimizing the performance of drilling fluid loss treatment.

Research on the rheological and flow characteristics of a supramolecular gel in fractures

AbstractLoss circulation is one of the major concerns in drilling and well construction. An effective way to control drilling fluid loss and strengthen the wellbore is to plug fractures and holes with loss circulation materials. In this work, a hydrophobic association supramolecular hydrogel GP‐A developed by n‐dodecylacrylamide, methacrylamide and 2‐acrylamide‐2‐methylpropylsulfonic acid was proposed as a potential lost circulation material for malignant drilling fluid loss. The results show that the initial decomposition temperature of GP‐A was 172°C, and the flow characteristics conform to the Herschel‐Bulkley model with yield stress. Microstructural analysis shows that GP‐A gel with a 3D spatial network, and hydrogen bonds between branched chains form a dynamically recoverable structure. Based on POLYFLOW, the Phan Thien–Tanner model with viscoelastic parameters was used to simulate the viscoelastic flow characteristics of the fluid in fractures. The higher the concentration is, the greaterK, and the higher the inlet driving pressure, while the nonlinear relationship between the driving pressure and the gel slug length is evident. The introduction of supramolecular gel polymer as a loss circulation material is an innovative research topic, which provides a new method to simulate the flow of polymer fluid in fractures.

Nanosilica-Based Loss Circulation Composition to Cure Moderate to Severe Losses

Abstract The loss circulation composition comprising a combination of a nanoparticle-based dispersion and a chemical activator has been designed to treat moderate to severe losses. The nanomaterial used is an environmentally friendly nanosilica-based dispersion. The composition is designed to give delayed gelling of the nanoparticle-based dispersion. A major advantage of this technology is its ability to place the composition into the target loss circulation zone before the nanoparticle-based dispersion gels up. Premature gelling of the nanoparticle-based dispersion would avoid premature setting of the treatment fluid before it reaches the target zone. The newly developed system can be used effectively up to 300 °F. In this paper, experiments have been performed with three different types of nanoparticles differing in their surface charges and particle sizes. Two negatively charged nanoparticle-based dispersions with a particle size of 5 nm and 17 nm, respectively, and one positively charged nanoparticle-based dispersion with a particle size greater than 17 nm have been evaluated as loss circulation materials. Two different types of chemical activators, one organic and the other inorganic, have been used in this study, and their effect on the gelling time has been evaluated. The gelling time experiments have been done at four different temperatures viz. 150 °F, 200 °F, 250 °F, and 300 °F. The effect of activator concentration and different shear rates on the gelling time of the three nanoparticle-based dispersions has been studied. Permeability plugging tests have been performed using 2 mm slotted disks to evaluate the effectiveness in controlling moderate to severe losses.

PEMANFAATAN LIMBAH STYROFOAM SEBAGAI LOSS CIRCULATION MATERIAL PADA LUMPUR PEMBORAN PANAS BUMI

Lumpur pemboran merupakan faktor penting dalam operasi pemboran. Lumpur pemboran dapat berfungsi dengan baik, apabila lumpur selalu dikontrol sifat-sifat fisiknya. Penelitian ini, memanfaatkan limbah Styrofoam yang digunakan sebagai aditif dalam lumpur pemboran pada pemboran panas bumi untuk mengatasi Loss Circulation. Sifat fisik lumpur yang digunakan sebagai pengontrol untuk mengatasi loss circulation meliputi berat jenis (densitas), viscositas, filtration loss. Tujuan dari penelitian ini adalah membuktikan limbah styrofoam yang dapat dimanfaatkan sebagai Loss Circulation Material. Metodologi yang digunakan dalam penelitian sesuai dengan Standar American Petroleum Institute API 13A. Sampel yang digunakan pada pengujian menggunakan empat sampel lumpur bor dan tiga kali pengukuran. Sampel 1 lumpur pemboran tanpa aditif, sampel kedua lumpur pemboran plus aditif 1 gram Styrofoam, sampel kedua lumpur pemboran plus aditif 2 gram styrofoam sampel kedua lumpur pemboran plus aditif 3 gram styrofoam Bahan-bahan yang digunakan antara lain aquadest, bentonite dan limbah styrofoam yang dihaluskan. Hasil penambahan styrofoam tiga gram didapatkan nilai densitas 8.63 ppg, mud cake bernilai 1,254 mm, volume filtrate 13 ml per tiga puluh menit dengan pH 9 dan memenuhi standar API., penambahan limbah styrofoam menurunkan densitas dan menambah ketebalan mud cake sehingga limbah styrofoam dapat digunakan sebagai loss circulation material pada pemboran panas bumiKata kunci: Limbah styrofoam, lumpur pemboran, loss circulation material, panas bumi

Hybrid machine learning algorithms to enhance lost-circulation prediction and management in the Marun oil field

Drilling fluid loss of circulation is a challenging issue to resolve for many oil and gas wells as drilling progresses. It imposes enormous expenses on drilling industry. One of the common practices to solve this problem or make it less severe is introducing various loss circulation materials (LCM) into the circulating drilling fluid. The ability to predict the amount of mud loss before drilling a particular formation would provide engineers with invaluable information to assist them in selecting appropriate LCM properties such as particle size distribution. In this study, a number of heuristic search algorithms including genetic algorithm (GA), particle swarm size (PSO), and cuckoo search algorithm (COA) are combined with two machine-learning techniques namely multilayer perception (MLP) neural network and least square support vector machine (LSSVM) to present different hybrid algorithms in prediction of lost circulation. The established database consists of 2820 cases (datasets) extracted from available drilling reports of 305 drilled wells in the Marun oil field. These datasets are associated with drilling operation variables, formation specifications, and drilling mud characteristics which totally include 18 input variables and 1 output. Pre-processing of data involves filtering with Savitzky-Golay (SG) filter and ranking features using wrapper method. Results show that hybrid intelligent models are highly capable of predicting lost circulation before drilling a certain formation. Furthermore, LSSVM-COA and LSSVM-PSO achieve coefficients of determination of 0.9424 and 0.9391, respectively, making them the two most accurate models. GA cannot match the prediction performance of the other two algorithms in enhancing machine-learning techniques for this purpose. MLP-GA with a coefficient of determination (R2) and RMSE of 0.9304 and 25.26 (bbl/hr), respectively, yields the weakest prediction performance. Hybrid intelligent models, coupling optimizers and machine learning algorithms show themselves to be superior to applying standalone machine-learning methodologies for predicting loss of circulation.

Development of a Polyacrylamide-Based Mud Formulation for Loss Circulation Treatments

Abstract Loss circulation materials in the last two decades have witnessed a lot of developments and implementations. New technologies and materials are introduced to treat various types of loss zones. However, the success rate is still very low due to many uncertainties in the selection of types and particle size of the bridging materials. In addition, there are many operational restrictions such as the risk of plugging and pumping difficulties when large size of particle is needed, especially in deep-water drilling. In this study, polyacrylamide (PAM) crosslinked with polyethylenimine (PEI) is introduced as polymer-based mud for loss circulation treatment. The PAM/PEI systems have wide applications in water shutoff for high water production zones and are known for their strong gel and exceptional rheological properties. This study provides a rheological method for screening of PAM/PEI-based drilling formulation with optimized molecular weight and concentrations. Comparative analysis of rheology of non-crosslinked and crosslinked polyacrylamide with other drilling fluids additives as well as proper mixing procedures are provided. The results achieved in this study are used as a strong tool to design a polymer-based mud with competitive rheological properties which achieved an 80% reduction in fluid loss when compared with other conventional loss circulation materials.

Loss circulation prevention in geothermal drilling by shape memory polymer

Geothermal formations are naturally fractured with large fracture openings and networks. This can often lead to frequent drilling fluid loss events which is a major contributor to the cost and non-productive time in geothermal drilling. Development of smarter technologies and methods to tackle problem lost circulation is vital for geothermal drilling cost reduction required for geothermal energy to be recognized as a competitive alternative energy source. Mitigation of this problem and other drilling problems such as stuck pipe can minimize overall project cost.In this paper, a thermoset shape memory polymer that can be activated by formation natural heat was assessed to seal near wellbore fractures in geothermal wells. The performance of the shape memory polymer (SMP) was evaluated using artificial fractures created in aluminum discs and cylindrical granite cores. Rheology and particle size distribution were considered. A novel testing setup was built for this work, which allows testing of sealing efficiency under dynamic conditions at high temperature. Analysis showed that the SMP has efficiently succeeded in forming a strong plug inside the fractures and stopped fluid loss at high sealing pressure. This smart loss circulation material can expand within the fractures to reduces non-drilling time and strengthen the wellbore in high-temperature drilling operations.

Cross-linked polyacrylamide gel as loss circulation materials for combating lost circulation in high temperature well drilling operation

Cross-linked polymer gel has been broadly used to plug severe lost circulation and to improve the strength of the near-wellbore in natural fracture or carbonate cave strata. Gelation time and gel strength are the key factors for gel plugging. In this study, a cross-linked polymer gel with controlled gelation time and high gel strength was fabricated at high temperature, named HTCMG. It was prepared from an acrylamide monomer, crosslinking agent and initiator by free radical polymerization. To extend gelation time at high temperature, colophony was used here to encapsulate the initiator. This complex was characterized under the Fourier transform infrared spectroscopy (FT-IR), by thermogravimetric analysis (TGA) and under the scanning electronic microscopy (SEM). The effects of pH, temperature, monomer concentration and salt concentration on gelation time were assessed. To examine the viscoelastic property and tensile strength of HTCM, HAKKE Mars 40 and uniaxial compression apparatus were employed, respectively. The plugging property of HTCMG was tested by the core displacement test and high-temperature and high-pressure (HTHP) fracture plugging test. According to the results, HTCMG can form gel in temperature range of 80–150 °C, and the gelation time can be practically adjustable. The results of the core displacement test revealed that the bearing capacity of HTCMG can reach a peak of 9.8 MPa at 150 °C, and it can effectively plug 3 mm-width slot. HTCMG is characterized by a lower plugging time, a higher successful plugging ratio and lower economic cost than normal loss circulation materials, suggesting that HTCM is useful for addressing the lost circulation of high-temperature well, and it is of huge significance to engineering application.

PENANGGULANGAN LOST CIRCULATION DENGAN MENGGUNAKAN METODE UNDER BALANCED DRILLING PADA SUMUR Y, BLOK Z

Drilling operation is process for creating a hole before production operation. “CT” Well and “Y” Well is located at same area which is Z Block. Those wells are vertical offshore wells. “CT” Well had been drilled on 1971 before “Y” Well was drilled on 2009.While drilling “CT” Well occurred total loss circulation on 12 ¼” at 3928 ft and cured with injection of 375 bbl LCM (Loss Circulation Material) with concentration 300 ppb but the loss circulation still occurred. Then total loss circulation occurred again at depth 4343 ft and 4545 ft. It cured with the same method but it didn’t succeed at all. Thus, using blind drilling method is the only option to anticipate the loss. This operation took 17 days using those methods.Well “Y” on 12 ¼” was drilled conventionally. When it reached depth 2910 ft occurred total loss circulation. Based on “CT” Well, using Under Balanced Drilling Method is the best way to anticipate the total loss circulation. This method only took 8 days Keywords : Grid Model Reservoir, Single Porosity, Grid Cell.

Engineered Fiber Based Lost Circulation Pill to Abridge Lost Circulation of Geothermal Well

Loss circulation is a major problem and known as the biggest challenge during drilling and well construction.This can leadsto various consequences,such as stuck pipe, loss of material and time to combat the losses, and even losing the well itself. Severe loss circulation conditions are often met while drilling geothermal wells in Indonesia. Partial to total losses have start experienced since drilling the surface section. Cement plugs is one of the conventional methods to cure losses. Number of cement plugs differ from one well to another well. Even in some wells, number of cement plugs performed for loss circulation plug can be over 30 times with total of more than 4,000 barrels of cement slurry pumped. Solution other than basic loss circulation material and cement plug must be developed to optimize curing loss time. Engineered fiber base concentration which is include; Base Fluid, LCM and Solid Package was obtained from simulation, then trial and error in laboratory was conducted. Based on the final recipe, the control pill was able to hold pressure and not leaking, even when using 5 mm grid clearance. Additional combined stiff fiber and flexible fiber with concentration of 6 lbs/bbl sufficient to hold exessive loss circulation.

Study of the pressure drop and the flow of loss circulation material suspensions in a physical simulator of fractures

The loss of fluid to the rock formation is one of the main problems encountered in oil well drilling operations. To mitigate this problem, particulate materials responsible for sealing fractures or for strengthening the well are used. The main objective of this work is to study the flow of Non-Newtonian suspensions through fractures, the pressure drop associated with this flow and the process of sealing fractures using particulate materials suspensions. The flow through fracture of Non-Newtonian suspensions was studied using an apparatus that allowed these fluids to flow through three different artificial fractures with widths of 2 mm, 5 mm and 10 mm and an average 1 cm depth. The suspensions were prepared by mixing water, viscosifying polymer and particulate materials based on laminar calcium carbonate. The particulate materials used are called fine and medium because they have different particle size distributions. The characterization of the solutions and suspensions was carried out from the rheological tests and the determination of the densities and the particle size distributions. The influence of factors such as flow rate, concentration and particle size distributions on the flow of the suspensions through fractures and its sealing capabilities were evaluated. The suspensions of the fine material particles were able to seal only the 2 mm fracture. The suspension composed of the particles of the medium material proved efficient in sealing the three fractures. A mathematical methodology was proposed with the objective of correlating the pressure drop and the flow rate of suspensions in fractures.

The effect of wellbore circulation on building an LCM bridge at the fracture aperture

Different laboratory experimental setups with slotted disks, simulating fractures’ apertures, have been used extensively to formulate effective loss circulation materials (LCM) recipes. The amount of fluid loss and sealing pressure have been used as the evaluation criteria. The question still remains is how valuable these tests are when LCM fluids are circulated in the wellbore to stop losses. The main objective of this work is to study the effect of the annular fluid flow on building an LCM bridge at the fracture aperture.To address the objective, a fluid loss apparatus has been developed to mimic wellbore circulation. Tapered slotted disks were placed upward in a cylinder filled with drilling fluid and LCM additives. Drilling fluid is pumped at the bottom of the cylinder and the wellbore circulation is simulated through the use of stirring paddle. Previously reported effective LCM recipes have been retested conventionally, no simulated circulation, and under simulated circulation condition (Scirc) with varying pump flow rates and tapered slotted disk sizes. A new term, sealing effectiveness ratio (SER), is introduced to effectively evaluate the sealing integrity of the LCM recipes at the Scirc.The results showed when stirring the sample, a higher fluid loss was required before the sample sealed and the maximum sealing pressure (Pmax) was lower than sealing pressures reported from conventional tests. Different LCM recipes required a different minimum flow rate for a seal to initiate at the Scirc. Increasing the flow rate improved the sealing effectiveness ratios of all LCM recipes. At high flow rates some recipes gave very similar Pmax as conventional tests while others lost more than 35% of their strength. At a given flow rate with larger opening size slot, the effect of Scirc was amplified as higher fluid loss was required to initiate a seal and a lower sealing effectiveness ratio was recorded. The most significant new finding is that LCM with lower specific gravity was less prone to the Scirc making them better preventive approach candidates.

Investigating Created Properties of Nanoparticles Based Drilling Mud

The success of drilling operations is heavily dependent on the drilling fluid. Drilling fluids cool down and lubricate the drill bit, remove cuttings, prevent formation damage, suspend cuttings and also cake off the permeable formation, thus retarding the passage of fluid into the formation. Typical micro or macro sized loss circulation materials (LCM) show limited success, especially in formations dominated by micropores, due to their relatively large sizes. Due to unique characteristics of nanoparticles such as their size and high surface area to volume ratio, they play an effective role in solving problems associated with the drilling fluid. In this study, we investigate the effect of adding Al2O3 and TiO2 nanoparticles into the drilling mud. Al2O3 and TiO2 nanoparticles were used in 20 and 60 nm of size and 0.05 wt% in concentration. Investigating the effects of temperature and pressure has shown that an increase in temperature can reduce the drilling mud rheological properties such as plastic viscosity, while an increase in pressure can enhance these properties. Also, the effects of pressure in high temperatures were less than those in low temperatures. Studying the effects of adding nanoparticles has shown that they can reduce the drilling mud rheological properties. Moreover, they can increase gel strength, reduce capillary suction time and decrease formation damage.