Drilling Time Research Articles

Physics-Based Swab and Surge Simulations and the Machine Learning Modeling of Field Telemetry Swab Datasets

Drilling operations are the major cost factor for the oil industry. Appropriately designed operations are essential for successful drilling. Optimized drilling operations also enhance drilling performance and reduce drilling costs. This is achieved by increasing the bit life (minimizing premature bit wear), drilling more quickly, which reduces drilling time, and also reducing tripping operations. This paper is presented in two parts. The first part compares the parametric physics-based swab and surge simulation results obtained from the Bingham plastic, power law, and Robertson–Stiff models. The aim is to show how the model’s predictions deviate from each other. Two 80:20 oil/water ratio (OWR) oil-based drilling fluids and two 90:10 OWR oil-based drilling fluids, 1.96 sg and 2.0 sg, were considered in vertical and deviated wells. Analysis of the simulation results revealed that the deviations depend on the drilling fluid’s physical and rheological parameters as well as the well trajectory. Moreover, the model’s predictions were inconsistent. Data-driven machine learning (ML) modeling is the focus of the second section. Data-driven modeling was performed using both software-generated datasets and field datasets. The results show that the random forest regressor (RF), artificial neural network (ANN), long short-term memory (LSTM), LightGBM, XGBoost, and multivariate regression models predicted the training and test datasets with higher R-squared and minimum mean square error values. Deploying the ML model in real-time applications and the planning phase would lead to potential applications of artificial intelligence for well planning and optimization processes.

Picosecond laser microvia drilling of ABF material using MHz burst mode

We report on a comprehensive study of laser percussion microvia drilling of Ajinomoto build-up film (ABF) material using an ultrashort pulsed laser in MHz burst mode. After laser processing, microvia drilling quality is being evaluated by the fabricated diameter and taper using laser scanning microscopy and metallography. The influences of the incubation effect, heat accumulation and shielding effects as a result of pulse to pulse interactions are being discussed on the ablation threshold, penetration depth and laser microvia drilling quality. We find that an increasing heat accumulation in MHz burst mode processing is responsible for the void formation and delamination of the insulating ABF layer. Therefore, the parameter clearance is introduced to evaluate these effects on the microvia sidewalls. For a comparable clearance, applying 2 intra-burst pulses achieves an average reduced taper of down to 19.5% compared to single pulse mode. At the same time, a reduced laser drilling time of 16.7% per microvia highlights the enormous potential of the MHz burst mode for laser drilling of ABF material in printed circuit board fabrication.

Enhancing the drilling efficiency through the application of machine learning and optimization algorithm

This article presents a novel Artificial Intelligence (AI) workflow to enhance drilling performance by mitigating the adverse impact of drill-string vibrations on drilling efficiency. The study employs three supervised machine learning (ML) algorithms, namely the Multi-Layer Perceptron (MLP), Support Vector Regression (SVR), and Regression Decision Tree (DTR), to train models for bit rotation (Bit RPM), rate of penetration (ROP), and torque. These models combine to form a digital twin for a drilling system and are validated through extensive cross-validation procedures against actual drilling parameters using field data.The combined SVR - Bit RPM model is then used to categorize torsional vibrations and constrain optimized parameter selection using the Particle Swarm Optimization block (PSO). The SVR-ROP model is integrated with a PSO under two constraints: Stick Slip Index (SSI<0.05) and Depth of Cut (DOC<5 mm) to further improve torsional stability. Simulations predict a 43% increase in ROP and torsional stability on average when the optimized parameters WOB and RPM are applied. This would avoid the need to trip in/out to change the bit, and the drilling time can be reduced from 66 to 31 h.The findings of this study illustrate the system's competency in determining optimal drilling parameters and boosting drilling efficiency. Integrating AI techniques offers valuable insights and practical solutions for drilling optimization, particularly in terms of saving drilling time and improving the ROP, which increases potential savings.

Percentile Rankings and Position Differences for Absolute and Allometrically Scaled Performance Measures From the National Football League Scouting Combine.

Gillen, ZM. Percentile rankings and position differences for absolute and allometrically scaled performance measures from the National Football League scouting combine. J Strength Cond Res 37(12): e613-e624, 2023-This study aimed to provide percentile rankings for absolute and allometrically scaled performance measures for National Football League (NFL) Scouting Combine subjects and determine if allometric scaling affected position-specific differences in performance measures. Subjects included American football players ( n = 3,015) who participated in the NFL Scouting Combines between 2015 and 2019. Subjects were divided into position groups: defensive backs (DBs, n = 562), defensive linemen (DL, n = 498), linebackers (LBs, n = 395), offensive linemen (OL, n = 505), running backs (RBs, n = 303), tight ends (TEs, n = 165), quarterbacks (QBs, n = 165), and wide receivers (WRs, n = 422). Performance measures included 40-yd dash time (with 10- and 20-yd split times), bench press repetitions to failure, vertical jump height, broad jump distance, pro-agility time, and L-cone drill time. Descriptive statistics were computed for all performance metrics and allometrically scaled performance metrics. One-way analyses of variance tested for position group differences for absolute and allometrically scaled performance measures. Percentile rankings for absolute and allometrically scaled performance measures were determined. Position-specific differences for absolute performance measures indicated that DB and WR tended to be faster, jump higher and further, and have greater change-of-direction capabilities compared with LB, QB, RB, and TE, who scored better in these respects than OL and DL. Allometric scaling revealed that DL, LB, RB, and TE tended to have superior performance than DB and WR, with QB and OL having the poorest performance. This study provides percentile rankings and the equation and parameters by which coaches and practitioners may allometrically scale data for evaluations of normalized performance measures from the NFL Scouting Combine.

In situ digital testing method for quality assessment of soft soil improvement with polyurethane

This study purposes an in situ testing method on quality assessment of soil improvement. Factual drilling data includes the spatial distribution and in situ strength of untreated and treated soil along three different drillholes measured by on-site drilling monitoring method. These factual drilling data can characterize the degree of soil improvement by penetration injection with permeable polyurethane. Result from on-site drilling monitoring shows that the linear zones represent constant drilling speeds shown in the plot of drill bit advancement vs. net drilling time, which indicates the spatial distributions of soil profile. The soil profile at the study site is composed of four layers, which includes fill, untreated silty clay, treated silty clay, and mucky soil. The results of soil profile are verified by the parallel site loggings. The constant drilling speeds profile the coring-resistant strength of drilled soils. By comparing with the untreated silty clay, the constant drilling speeds of the treated silty clay have been decreased by 13.0–62.8%. Two drilling-speed-based indices of 61.2% and 65.6% are proposed to assess the decreased average drilling speed and the increased in situ strength of treated silty clay. Laboratory tests, i.e. uniaxial compressive strength (UCS) test, have been performed with core sample to investigate and characterize in situ strength by comparing that with drilling speeds. Results show that the average predicted strengths of treated silty clay are 2.4–6.9 times higher than the average measured strength of untreated silty clay. The UCS-based indices of 374.5% and 344.2% verified the quality assessment (QA) results by this new in situ method. This method provides a cost-effective tool for quality assessment of soil improvement by utilizing the digital drilling data.

Drilling Conditions Classification Based on Improved Stacking Ensemble Learning

The classification of drilling conditions is a crucial task in the drilling process, playing a vital role in improving drilling efficiency and reducing costs. In this study, we propose an improved stacking ensemble learning algorithm with the objective of enhancing the performance of drilling conditions classification. Additionally, this algorithm aims to have a positive impact on automated drilling time estimation and the continuous improvement of efficiency. In our experimental setup, we employed various base learners, such as random forests, support vector machine, and the K-nearest neighbors algorithm, as initial models for the task of drilling conditions classification. To improve the model’s expressive power and feature relevance specifically for this task, we enhanced the meta-model component of the stacking algorithm by incorporating feature engineering techniques. The experimental results show that the improved ensemble learning algorithm achieves an accuracy and recall rate of 97% and 98%, respectively. Through continuous improvement in drilling operations, the average sliding time is reduced by 21.1%, and the average Rate of Penetration (ROP) is increased by 15.65%. This research holds significant importance for engineering practice in the drilling industry, providing robust support for optimizing and enhancing the drilling process.

Influence of Multiple Used Implant Drills on Their Cutting Performance and Fracture Resistance.

This study aimed to analyze the influence of multiple uses of zirconia implant drills on their cutting performance and bending strength. The hypothesis was that drill usage and sterilization cycles would not affect drilling time or flexural strength. Sixty zirconia twist drills from Z-Systems were used to drill in the angulus mandibulae region of fresh porcine jaws. The drills were divided into four groups based on the cycle count, and the drilling time was measured. Bending strength tests were conducted using a universal testing machine, and statistical analysis was performed using ANOVA tests. The results showed that drilling times followed a normal distribution, and significant differences were observed in drilling times between group 1 and the other groups for the pilot drill. However, no significant differences were found for ø3.75 mm and ø4.25 mm drills, and drilling times also varied significantly among different drill diameters, regardless of the cycle count. Flexural strength did not significantly differ among drill diameters or sterilization cycles. Overall, using and sterilizing zirconia implant drills had no significant impact on drilling time or flexural strength. Nevertheless, drilling times did vary depending on the diameter of the drill. These findings provide valuable insights into the performance and durability of zirconia implant drills, contributing to the optimization of dental implant procedures.

Optimization of cutting parameters by thrust force and time for drilling of aluminum 2024 T351

Abstract In this study, the cutting parameters were optimized according to the thrust force and operation time in the drilling of Al 2024 T351 alloy, which is preferred in the aerospace industry and therefore subjected to thousands of drilling processes with liquid cooling. Cutting speed (70, 90, and 110 m min−1) and feed rate (0.08, 0.1, and 0.12 mm tooth−1) were considered cutting parameters. Experiments were performed three tool types (HSS, HSSE-Co5, HSSE-Co5 TiAlN coated). Taksan TMC-700 V CNC vertical machining center with FANUC control panel was used for drilling, and ESIT AX3 load cell and NI cDAQ-9188, data acquisition system, were used for data collection. Signal noise was reduced by applying the exponential smoothing method to all force data obtained in the experiments. The maximum forces in the machining direction (z-axis) were determined for each hole. The time was calculated during the computer aided manufacturing process. Response surface optimizations, variance analyses (ANOVA), and regression analyses were performed using these determined maximum thrust forces and measured time.

Influence Study of Etching Time for Porous Silicon on Morphological, Optical, Electrical and Spectral Responsivity Properties

In this investigation, n-type (100) silicon wafers with a thickness of 600 ± 25 μm and resistance of 0.1-100 μΩ were used to manufacture porous silicon. With the aid of hydrofluoric acid (HF) with a 20% concentration, a current density of 20 mA/cm2, and various experimental drilling times of 5, 15, and 25 minutes with the fixation of other parameters, the photoelectrochemical etching method was successful. The morphology of porous silicon was investigated using scanning electron microscopy (SEM), the XRD- diffraction wide of porous silicon creation with rising apex peaks was confirmed, and (AFM) sponge-like morphology was seen, and the pore diameter grew larger as drilling time rose. In a drilling time of 15 minutes, it is able to quantify both the vibrational and electrical characteristics of the energy band gap using Raman analysis and PL detection. Investigate sample samples' current voltage readings (J-V) at various etching times. Additionally, we discovered devices with a broad wavelength that react to the response in the investigation of the spectrum response PS AL/PS/SI/Al as a photodetector.

FAILURE ANALYSIS OF CARBIDE TWIST-DRILL BIT FOR SMALL-SCALE GRANITE DRILLING

This paper deals with a failure analysis of WC-Co carbide-based twist drills used for small-scale granite drilling. A bench-top drill was used for this study. The aim of the study was to analyse a simulated in-situ rock-drilling operation normally carried out in mines. After a drilling time of 15 minutes, the drills were examined using scanning electron microscopy. On macroscopic observation, both cutting edges of the drills showed slight signs of abrasion, but these were not significant. The chisel edge was also abraded and showed some macroscopic abrasion marks. The electron micrographs showed various signs of decomposition at the micro and nano levels, including cracks in the WC grains, cavities in the grains, Co-binder erosion and some heavy abrasion marks. In addition, some parts of the carbide grains were covered with a thin layer of rock. The wear analysis is an important approach to understanding exactly the damage behaviour of the tool so that the material composition can be changed to avoid premature tool failure.

A new model for evaluating rock drillability considering the rock plasticity and chip hold down effect caused by hydrostatic column pressure under high confining pressure

The Yingqiong Basin in the northern part of the South China Sea is a region with large natural gas reserves. However, the high formation pressure and hydrostatic column pressure of the extra-thick mudstone section in this area present significant challenges to drilling operations. The mudstone has high plasticity and is very hard, and its thickness accounts for only 40% of the total footage, which results in pure drilling time accounting for over 75% of the total drilling time. To accelerate the rate of penetration (ROP) in this area, this study investigates the rock mechanics characteristics of mudstone under high confining pressure through experimental methods. The study reveals that the strength of the mudstone increases rapidly with increasing confining pressure, and the critical transformation stress of bottom-hole mudstone is around 45 MPa. Moreover, a cylindrical-cutter micro bit was developed, and the drillability of mudstone was tested under high confining pressure and hydrostatic column pressure, which further confirms that 45 MPa is the critical stress for a sudden increase in mudstone's drillability. Based on multiple regression analysis, the acoustic interval transit time, hydrostatic column pressure, and argillaceous content were identified as strong correlation parameters for the drillability of plastic mudstones. A new model for evaluating rock drillability considering rock plasticity and chip hold down effect caused by hydrostatic column pressure was developed, which provides effective guidance for the optimal design of bits and drilling fluid density in the extra-thick mudstone formations of the Yingqiong Basin. This study provides theoretical and technical support for the economic and efficient development of high-pressure gas fields in this area.

Analysis of the influence of surgical robot drilling parameters on the temperature of skull drilling based on Box-Behnken design.

It is easy to cause thermal damage to the bone tissue when the surgical robot performs skull drilling to remove bone flaps, due to the large diameter of the drill bit, the large heat-generating area, and the long drilling time. Therefore, in order to reduce the thermal damage during the robot-assisted skull drilling process, the relationship between the drilling parameters and the drilling temperature during the skull drilling was studied in this paper. Firstly, a dynamic numerical simulation model of the skull drilling process was established by ABAQUS, and a temperature simulation plan for skull drilling was designed based on the Box-Behnken method. Then according to the simulation results, a quadratic regression model of drill diameter, feed rate, drill speed, and drilling temperature was established by using the multiple regression method. By analyzing the regression model, the influence of drilling parameters on the drilling temperature was clarified. Finally, the bone drilling experiment was carried out, and the error percentage was lower than 10.5% through the experiment to verify the reliability of the conclusion, and a safety strategy was proposed to ensure the safety of the surgical drilling process based on this experiment.

Optimizing sampling frequency of surface and downhole measurements for efficient stick-slip vibration detection

Drilling vibrations significantly impact drilling operations with high costs due to early downhole equipment failure and loss of productive time. Stick-slip vibrations, a severe form of torsional vibrations, is known to be present up to 50% of total drilling time, making it a topic of immense concern and research. An ongoing discussion in the industry is regarding the reliability of surface measurements for early detection of severe downhole bit sticking. Moreover, most surface measurements are sampled at lower frequency rates closer to 1 Hz. Recently, the implementation of advanced data acquisition modules in downhole subs has greatly improved our understanding of drilling vibrations through high resolution data, sampled up to 10 kHz. However, with a wide range of sampling frequency to choose from different available tools, a critical question remains unanswered. What is an optimal and adequate sampling frequency for early detection of downhole vibrations using both surface and downhole measurements? The paper addresses the question with a focus on stick-slip vibrations through an experimental investigation. Stick slip tests are repeated for different sampling frequencies of surface and downhole measurements and the stick slip index for each case is calculated. The stick-slip index varies for different sampling frequency even though the vibration tests remain completely identical. It was inferred that sampling frequency of measurements greatly impact the detection of downhole vibrations. Even though stick-slip vibrations are characteristically low frequency vibrations (≤2Hz), a minimum of 10Hz sampling frequency is recommended for detection of stick-slip vibrations. Moreover, all characteristics of stick-slip vibrations including bit sticking, bit RPM peaks and negative bit RPMs are clearly observed at a minimum of 100Hz sampling rate.

Preclinical dental students self-assessment of an improved operative dentistry virtual reality simulator with haptic feedback

To test and evaluate the second installment of DENTIFY, a virtual reality haptic simulator for Operative Dentistry (OD), on preclinical dental students, by focusing on user performance and self-assessment. Twenty voluntary unpaid preclinical dental students, with different background experience, were enrolled for this study. After the completion of an informed consent, a demographic questionnaire, and being introduced to the prototype (on the first testing session), three testing sessions followed (S1, S2, S3). Each session involved the following steps: (I) free experimentation; (II) task execution; S3 also included (III) completion of questionnaires associated with the experiment (total of 8 Self-Assessment Questions (SAQ)); and (IV) guided interview. As expected, drill time decreased steadily for all tasks when increasing prototype use, verified by RM ANOVA. Regarding performance metrics (Comparisons by Student’s t-test and ANOVA) recorded at S3, in overall, a higher performance was verified for participants with the following characteristics: female, non-gamer, no previous VR experience and with over 2 semesters of previous experience of working on phantom models. The correlation between the participants’ performance (drill time), for the four tasks, and user self-assessment evaluation, verified by Spearman’s rho analysis, allowed to conclude that a higher performance was observed in students who responded that DENTIFY improved their self perception of manual force applied. Regarding the questionnaires, Spearman’s rho analysis showed a positive correlation between the improvement DENTIFY inputs on conventional teaching sensed by students, also enhancing their interest in learning OD, their desire to have more simulator hours and the improvement sensed on manual dexterity. All participating students adhered well to the DENTIFY experimentation. DENTIFY allows for student self-assessment and contributes to improving student performance. Simulators with VR and haptic pens for teaching in OD should be designed as a consistent and gradual teaching strategy, allowing multiplicity of simulated scenarios, bimanual manipulation, and the possibility of real-time feedback to allow for the student’s immediate self-assessment. Additionally, they should create performance reports per student to ensure self-perception/criticism of their evolution over longer periods of learning time.

Application Research of Borehole Cleaning Evaluation System Based on Cuttings Weighing

Due to complex working conditions and cuttings migration mechanism and other factors, cuttings bed is easy to form in deviated well section and extended reach horizontal well section, and too high cuttings bed is easy to cause a series of complex downhole accidents, such as bit mud bag, wall collapse, stuck drilling and holding in drilling. The borehole cleaning evaluation system based on cuttings weighing can collect the cuttings returned in real time. The system combines the real-time cuttings flow rate, theoretical cuttings volume, actual cuttings volume and other data to evaluate the borehole cleaning situation and provide guidance for field drilling construction. At the same time, the drilling optimization analysis module is designed in the system. The module adopts the combination of comprehensive logging data and geological logging data, combining the advantages of comprehensive logging and geological logging, which can realize the real-time drilling time optimization analysis to the maximum extent. In this paper, the evaluation system of borehole cleaning based on cuttings weighing is studied and corresponding engineering application examples are given. It has high practical application value for borehole cleaning monitoring and evaluation, drilling aging optimization analysis and reducing non-productive time.

Research on the Formation and Plugging Risk of Gas Hydrate in a Deepwater Drilling Wellbore: A Case Study

At present, the formation mechanism of gas hydrate (hereinafter referred to as hydrate) plugging in the wellbore during deepwater drilling is not clear, so there are problems such as the overuse of hydrate inhibitors and the low utilization efficiency of inhibitors. Therefore, in view of the risk of hydrate formation and plugging under different working conditions during deepwater drilling, research was carried out on the wellbore hydrate formation area and wellbore hydrate deposition and plugging. Taking an atmospheric well in the South China Sea as an example, the wellbore annulus temperature field under different working conditions was combined with the hydrate formation phase curve to analyze the hydrate formation plugging risk under different working conditions during deepwater drilling, and the hydrate formation risk region of the wellbore under different working conditions was obtained. The effects of the drilling fluid circulation rate, injection temperature and drilling fluid viscosity in the wellbore annulus on the risk zone and subcooling of the wellbore hydrate formation were predicted. A deepwater drilling wellbore hydrate deposition plugging model was developed, based on which the dynamic deposition of the hydrate in the wellbore was predicted quantitatively. The results of the study showed that: (1) Increasing the circulation rate of drilling fluid, drilling fluid inlet temperature and drilling fluid viscosity during deepwater drilling can effectively reduce the hydrate formation region and subcooling, thus reducing the hydrate formation. (2) The risk of plugging by hydrate formation basically does not occur during normal drilling. (3) Under the condition of using seawater bentonite slurry drilling fluid, the safe operating time for stopping drilling is 20 h, and the safe operating time for shutting in and killing the well is 30 h.

Experimental evaluation of different influencing parameters on cutting transport performance (CTP) in deviated wells

• CTP in deviated wells is affected by influencing parameters. • CTP has enhanced up to 8% by increasing viscosity with constant velocity. • Increasing additional viscosity results in a 12% reduction in CTP. • Hole inclination above 60 degrees has a positive effect on CTP which is up to 40%. • Velocity has a significant impact on CTP with a maximum of 98%. Globally, fuel energy has become a crucial issue in fulfilling energy demand; new oil/gas wells should be drilled to achieve the well target safely and efficiently. Cutting transport in deviated wells is directly affected by influencing parameters such as viscosity, annulus velocity of drilling mud, and hole inclination. Therefore, hole cleaning investigation requires a deep understanding of all influential parameters, as cuttings transport significantly affects drilling costs, time, and oil/gas well integrity. Poor hole cleaning efficiency could cause many drilling issues, including excessive torque and drag, Pipe washout and jamming, bit balling and washout, etc. The results of this study were utilized to investigate cutting transport performance, employing three different kinds of drilling mud. The investigational work was performed by a 10-feet elongated invisible pipe of 5-inch diameter and a steel pipe of 2-inch diameter as the test section. The cutting transport performance (CTP) was computed based on weight data for every single test. At different flow regimes, viscosity was examined in addition to two other influential parameters, namely fluid velocity and hole inclination. At all angles, during turbulent flow, Cutting Transport performance has enhanced up to 8% by increasing viscosity while keeping velocity constant. Nevertheless, an increasing additional amount of viscosity will turn the flow condition from turbulent to transient or laminar flow, resulting in a 12% reduction in CTP. It also shows that increasing hole angle above 60 degrees positively affects cuttings transport performance. It will be improved up to 40%. Moreover, a maximum of 98 percent CTP can be attained by drilling fluid velocity. Therefore, this study properly investigates the influence of viscosity, velocity, and hole inclination on cutting transporter performance, as a result saving drilling time and reducing hidden costs, as well as lead to a prediction of the carrying capacity of fluids and facilitating the optimum design of vertical and directional wells. Moreover, this study provides a guideline to analyze and enable the adjustment of drilling parameters to optimize the overall drilling process.

Techno-Economic Investigation of Geothermal Development in Sedimentary Basins

Abstract Models of the enhanced geothermal systems (EGS) in super-hot igneous rocks have demonstrated significantly higher heat transfer rates and power production compared to conventional geothermal systems. On the other hand, along with the high upfront costs, the major geological and technical challenges associated with drilling super-hot EGS wells in igneous rocks constrain the development of geothermal systems and prevent their worldwide application. Meanwhile, geothermal energy development in sedimentary basins could provide clean energy production with relatively lower investment costs compared to super-hot EGS development in igneous rocks. A significant amount of data, knowledge, and expertise has been gathered through decades of drilling and development of oil and gas wells in sedimentary basins. Application of this experience and data for geothermal drilling can eliminate and reduce costs of subsurface data gathering, well drilling, and completion. This paper investigates the economic viability of geothermal energy production systems in sedimentary basins. The study provides initial time-to-hit temperature (THT) and cost-to-hit temperature (CHT) maps across the US based on the well depth, total drilling and completion time, and total well cost data. Combined with sedimentary basin maps and underground temperature maps, THT and CHT maps could be utilized to place EGS wells and other geothermal systems applications at the most favorable locations in the US.

Frequent Event Pattern Extraction of Drilling Time Series Using Change Point Detection and Event Sequence Generation

In drilling processes, non-stationary phases corresponding to shifts between operating conditions and changes in downhole formations typically lead to false alarms. Extracting these frequent event patterns is critical to build drilling process monitoring and fault diagnosis models. This study aims to extract the frequent event patterns associated with non-stationary phases in drilling time series. In this way, diversified information related to signal changes under normal conditions can be obtained, which is beneficial for suppressing false alarms and improving fault detection performance. The main contributions of this study are twofold: 1) a non-stationary phase detection method is proposed to extract drilling frequent event patterns based on t-distributed stochastic neighbor embedding and relative unconstrained least-squares importance fitting; 2) an event sequence generation method is proposed to express drilling frequent event patterns with a group of symbols. The effectiveness of the proposed method is demonstrated by data from a real drilling project.

Does drilling affect the hearing of contralateral normal ear after mastoid surgery?

&lt;p&gt;&lt;strong&gt;Background:&lt;/strong&gt; Chronic otitis media (COM) is a recurrent infection of the middle ear and/or mastoid air cells affecting 2-3% of global population. Mastoidectomy is the mainstay of the treatment of COM. Bone drilling during mastoidectomy procedure exposes both the ears to acoustic trauma leading to sensorineural hearing loss. The present study was conducted to assess the possible deleterious effect of drilling on hearing of contralateral normal ear by monitoring pre-operative and post-operative pure tone audibility (PTA) and otoacoustic emissions (OAE). Aims and objectives were to evaluate the effect of drill- generated noise on hearing in non-operated ear during mastoidectomy in terms of hearing loss, its nature and duration and recovery of hearing loss.&lt;/p&gt;&lt;p&gt;&lt;strong&gt;Methods:&lt;/strong&gt; An observational study was carried out in ENT department at SMS medical college and hospital, Jaipur. Total 40 patients were studied. Pre-operative and post-operative PTA and OAE were studied and compared. Mean drilling time during mastoid surgery was also studied.&lt;/p&gt;&lt;p&gt;&lt;strong&gt;Results:&lt;/strong&gt; Out of 40 subjects, maximum patients were 11-20 years of age group (37.5%) with female preponderance (57.5%). All had undergone mastiodectomy. Only 6 (15%) subjects had transient sensorineural hearing loss of contralateral normal ear as determined by comparing pre-operative and post-operative PTA and OAE. The mean recovery time was 2-3 days. The study had shown significant effect of drill generated noise on hearing of contralateral healthy ear following mastoidectomy.&lt;/p&gt;&lt;p&gt;&lt;strong&gt;Conclusions&lt;/strong&gt;: Drill-generated noise can’t be lowered to a great extent therefore drilling time should be minimized during mastoid surgeries.&lt;/p&gt;