High density single-unit human cortical recordings using the Neuropixels probe

A fundamental unit of neural computation is the action potential. While significant advances have been made in the ability to sample action potentials of large numbers of individual neurons in animal models, translation of these methodologies to humans has been lacking due to clinical time constraints, electrical noise in the operating room, and reliability of the methodology. Here we present a reliable method for intraoperative recording of dozens of neurons in humans using the Neuropixels probe, yielding up to ~100 simultaneously-recorded single-units (n=596 across 11 recordings in 8 participants). Most single-units were active within 1 minute of reaching target depth, compatible with clinical time constraints. Cell pairs active close in time were spatially closer in most recordings, demonstrating the power to resolve complex cortical dynamics. Altogether, this approach provides access to population single-unit activity across the depth of human neocortex at scales previously only accessible in animal models.

Breaking ERD Records with Optimized Engineering and Practices: Making the Impossible Possible

Long-extended reach drilling (ERD) well has become necessary to reach untapped resources. This paper will describe pre-planning, execution and post results of drilling ERD wells with large bore design of 12¼" as the main step out section and deploying 9⅝" casing on shallow TVD of 4,200’. Progressive increase of the ERD ratio and complexity from one well to the next was planned and executed till we reached the longest well deploying 8 KM of 9⅝" casing with 5.4 ERD ratio at 26,179' TD horizontally all the way. A learning curve was established on drilled wells while progressively increasing reach and complexity. Subject well was the longest of any well planned in the field by far. Success involved implementation of technically modeled engineered solutions and verified during execution. Operational procedures including but not limited to: proper planning and execution of well profile to ensure optimum placement in a specific formation and minimum side forces. Drilling and tripping procedures to ensure the lowest friction factor (FF) and allow drilling to target depth (TD) with optimum rig capability. Engineered solution for casing running technologies, which involved rotation and conventional running and floatation. The longest ERD well was drilled to 26,179' TD with field ROP record in 12¼" hole section, maintaining very good hole quality proved by smooth bit trips out of hole and the final trip at TD on elevators. Hole cleaning and fluids strategy was developed and executed efficiently to measure FFs as low as possible for successful 9⅝" deployment. Engineered solution was proposed for 9⅝" deployment and was successfully trial tested on a shorter well to validate simulations. Casing rotation FFs came close to the modeled FFs. The 9⅝" Casing was deployed to bottom as planned and the cement job was performed successfully. Various records were achieved: the subject well achieved the deepest 9⅝" horizontal casing, the deepest 12¼" horizontal at TVD shallower than 5,000'. The longest 12¼" horizontal open hole at TVD shallower than 5,000' with section footage of 16,164'. The 9⅝" casing was deployed as a long string, eliminating the cost and challenges of a liner hanger and the need for a future tieback and also keeping hole sizes available for main and contingency sections to drill the reservoirs ahead. In addition to existing developed procedures and practices for ERD wells, subject well was dealing with the challenge of drilling a long 12 ¼" hole with a torque limitation of 30K lbsf.ft on TDS, and 4200 psi on surface equipment, and running the longest casing horizontally at such a shallow TVD, which is being done the first time globally. The success proved that challenging ERD wells can be drilled with optimum investments on rig capabilities.

Success Implementation of Pressurized Mud Cap Drilling in Offshore East Java Prospect, Avoid Rig Flat Time During Loss Circulation and Continue Drilling with 400psi in the Annulus to Reach Target Depth Through Fractured Carbonate Formation in 2 Days

The offshore East Java laid numerous carbonate formation, where depending on area, carbonate formation is exercised as the reservoir. The carbonate exploration drilling campaign, which is naturally fractured, risks the operation not just from safety aspect but also deliverability of well objective to explore uncovered reserve in the area. In this well, total loss circulation was experienced while drilling, despite no record of similar event from offset wells data. The field operator determined to call out Rotating Control Device (RCD) and installed prior to drilling 12.25in. hole section. The Pressurized Mud Cap Drilling (PMCD) method is prepared in advance as mitigation plan to overcome the exploration uncertainties. PMCD is one of the Managed Pressure Drilling (MPD) variants used in oil and gas wells that experience severe to total loss circulation. PMCD method involves drilling with closing flowline valve completely while using RCD system to seal the annulus. While drilling the 12.25in section, absence of return fluid observed as drill string penetrates the carbonate reservoir section (target formation). Activation of the annulus flooding system enables to pumps seawater through annulus, continued with pulling out the string to last casing shoe, and then installation of RCD bearing assembly to convert drilling strategy into PMCD method. As the PMCD components required such as RCD and drill string Non-Return Valve already equipped and all associated procedures prepared in advance, swift transition to PMCD mode results to lesser drilling flat time. After reaching target depth, the PMCD setup also assists in the deployment of open hole logging operation by installing RCD logging adaptor. With the successful PMCD implementation, the field operator managed to reduce drilling risks, reach exploration target successfully, reduce flat times and increase in ROP. This paper present success story of PMCD well drilled and lessons learned as the operator evolves to improve PMCD execution further.

A computational study on the optimization of transcranial temporal interfering stimulation with high-definition electrode using unsupervised neural network

Transcranial temporal interfering stimulation (tTIS) can focally stimulate deep parts of the brain, which are related to specific functions, by using beats at two high AC frequencies that do not affect the human brain. However, it has limitations in terms of calculation time and precision for optimization because of its complexity and non-linearity. We aimed to propose a method using an unsupervised neural network (USNN) for tTIS to optimize quickly the interfering current value of high-definition electrodes, which can finely stimulate the deep part of the brain, and analyze the performance and characteristics of tTIS. A computational study was conducted using 16 realistic head models. This method generated the strongest stimulation on the target, even when targeting deep areas or multi-target stimulation. The tTIS was robust with target depth compared with transcranial alternating current stimulation, and mis-stimulation could be reduced compared with the case of using two-pair inferential stimulation. Optimization of a target could be performed in 3 min. By proposing the USNN for tTIS, we showed that the electrode currents of tTIS can be optimized quickly and accurately, and the possibility of stimulating the deep part of the brain precisely with transcranial electrical stimulation was confirmed.

Abstract 9499: Prehospital Factors Associated With Cardiopulmonary Resuscitation Performance in Out-of-Hospital Cardiac Arrests

Introduction: Although high quality cardiopulmonary resuscitation (CPR) has been associated with improvements in survival from cardiac arrest, little is known about the arrest factors that influence CPR performance. This study examined the association between CPR performance and patient and arrest factors in out-of-hospital cardiac arrest (OHCA). Methods: A retrospective observational study using data from a statewide cardiac arrest registry in Victoria, Australia. The study included 2,408 adult, medical OHCA patients who arrested between 11 February 2019 and 10 February 2021. Fractional and logistic regression models were used to analyse factors associated with CPR performance outcomes, including the proportion of compressions at target depth and target rate and a compression fraction ≥90%. Results: The median proportion of compressions at target depth and target rate were 80% (interquartile range [IQR] 58, 92.5) and 62% (IQR 40, 79), respectively, and 70% achieved a compression fraction ≥90%. After multivariable adjustment, achieving a compression depth in the target range was associated with female sex (OR 1.14 [95% CI: 1.02, 1.28]), patient weight (per 10 kg increase, OR 1.08 [95% CI: 1.05, 1.12]), aged care facility location (OR 0.74 [95% CI: 0.58, 0.94]), fire-fighter presence (OR 1.29 [95% CI: 1.14, 1.46]), resuscitation duration (per 5 min increase, OR 1.08 [95% CI: 1.06, 1.10]) and number of rescuers (per 1 person increase, OR 1.06 [95% CI: 1.03, 1.09]). Achieving compressions within target rate were associated with public location (OR 0.81 [95% CI: 0.72, 0.91]) and fire-fighter presence (OR 1.12 [95% CI: 1.02, 1.24]). Achieving a compression fraction ≥90% was associated with female sex (OR 0.75 [95% CI: 0.62, 0.91]), arrests witnessed by emergency services (OR 0.44 [95% CI: 0.32, 0.61]), initial shockable rhythms (OR 0.66 [95% CI: 0.53, 0.81]), fire-fighter presence (OR 1.24 [95% CI: 1.01, 1.54]) and resuscitation duration (per 5 min increase, OR 1.05 [95% CI: 1.02, 1.08]). Conclusion: This study demonstrates that several prehospital factors that are associated with CPR performance which may help inform operational strategies to improve OHCA outcomes.

A Computational Study On The Optimization of Transcranial Temporal Interfering Stimulation With High-Definition Electrode Using Unsupervised Neural Network

Transcranial temporal interfering stimulation (tTIS) can focally stimulate deep parts of the brain, which are related to specific functions, by using beats at two high AC frequencies that do not affect the human brain. However, it has limitations in terms of calculation time and precision for optimization because of its complexity and non-linearity. We aimed to propose a method using an unsupervised neural network (USNN) for tTIS to optimize quickly the interfering current value of high-definition electrodes, which can finely stimulate the deep part of the brain, and analyze the performance and characteristics of tTIS. A computational study was conducted using 16 realistic head models. This method generated the strongest stimulation on the target, even when targeting deep areas or multi-target stimulation. The tTIS was robust with target depth compared with transcranial alternating current stimulation, and mis-stimulation could be reduced compared with the case of using two-pair inferential stimulation. Optimization of a target could be performed in 3 min. By proposing the USNN for tTIS, we showed that the electrode currents of tTIS can be optimized quickly and accurately, and the possibility of stimulating the deep part of the brain precisely with transcranial electrical stimulation was confirmed.

Successful and Efficient Drill & Drive Conductor Operation in Offshore East Java

Abstracts Conductor setting depth is critical to provide structural support for next drilling sections. The shoe strength must suffice for drilling ahead and avoid any washout and unstable zone. The objective is to design and run conductor smoothly in regards to engineering and operation aspect. Multidisciplinary approach including geotechnical, drilling engineering, and structure, was implemented during planning strategy. The pre-determined conductor setting depth was defined on the maximum mud weight to be used during drilling surface hole section in accordance to the formation strength below the conductor with the purpose of not inducing losses to the formation. Lateral distance between conductor and platform jacket pile was also analyzed to secure the jacket integrity. Anti-collision analysis was performed to prevent collision due to the existence of production well in same platform. Conductor pipe size and specification with some feature was defined to withstand under anticipated load and environment. To determine the way to achieve target depth and the suitability of hammer type, drivability analysis was performed with various anticipated condition. Considering shallow refusal depth, drill and drive was required to reduce shaft friction of soil. Another environmental challenge arise during conductor operation was unable to contain fluid and cutting returns from clean-out process causing return to cover part of the production platform facility. Some of technology were planned to mitigate this challenge. By having comprehensive conductor design, the conductor pipe in all four wells drilled has been successfully installed without any problem on platform jacket integrity and subsequent drilling section. This approach also enabled to efficiency of conductor installation where the number of clean-out and driving run could be reduced. The overflow return challenge could be fully contained by utilizing selfdesigned equipment. The overall operation days of conductor has shown improvement with 1.02 saving days on the last well which equivalent to amount of cost saving around USD 203,500.

Drilling the Point Pleasant-Utica Shale Fractured Formation During the COVID-19 Pandemic Utilizing CBHP MPD with a PMCD Contingency

Drilling the Point Pleasant-Utica formation in the Appalachian Basin has posed challenges to most operators, especially in Western Pennsylvania. A recent well drilled in this region demonstrated that with proper buy-in from the Operator, Constant Bottomhole Pressure (CBHP) Managed Pressure Drilling (MPD) could be the answer when planned and executed correctly. This paper drives the point that MPD is more than simply dropping chokes on location. Prior to drilling the well, the Operator initiated the communication very early with the MPD service provider and created an avenue to reduce the projected mud weight and develop a detailed CBHP MPD plan with a Pressurized Mudcap Drilling (PMCD) contingency. The anticipated challenges on this well were: High-pressure gas fractures, formation instability/shale breakout, severe/total loss of returns, inability to reach Target Depth, and casing/cementing issues. The Operator took time and worked with the new MPD service provider to carefully design and plan a new well (referred to as ‘Y1’ in this document), which helped execute the MPD part of the project within 30 days. In contrast, the MPD execution on a previous well (referred to as ‘X2’ in this document) with the older MPD service provider took more than 90 days. MPD execution on the new MPD well included dynamic influx management and loss mitigation, and understanding of the petro-physical conditions to reach the target. The significant factors that helped drill this well safely with a low Non-Productive Time (NPT) are excellent safety culture, communication, high quality and well-maintained MPD equipment, and a very knowledgeable and highly experienced MPD team. This project was finished within half of the budgeted Authorization for Expenditure (AFE), setting milestones in this region for this Operator.

Drone-mounted GPR surveying: flight-height considerations for diffraction-based velocity analysis

Recent studies highlight the potential of the drone platform for ground penetrating radar (GPR) surveying. Most guidance for optimising drone flight-heights is based on maximising the image quality of target responses, but no study yet considers the impact on diffraction travel-times. Strong GPR velocity contrasts across the air-ground interface introduce significant refraction effects that distort diffraction hyperbolae and introduce errors into diffraction-based velocity analysis. The severity of these errors is explored with synthetic GPR responses, using ray- and finite-difference approaches, and a real GPR dataset acquired over a sequence of diffracting features buried up to 1 m in the ground. Throughout, GPR antennas with 1000 MHz centre-frequency are raised from the ground to heights < 0.9 m (0-3 times the wavelength in air). Velocity estimates are within +10% of modelled values (spanning 0.07-0.13 m/ns) if the antenna height is within ½ wavelength of the ground surface. Greater heights reduce diffraction curvature, damaging velocity precision and masking diffractions against a background of subhorizontal reflectivity. Real GPR data highlight further problems of the drone-based platform, with data dominated by reverberations in the air-gap and reduced spatial resolution of wavelets at target depth. We suggest that a drone-based platform is unsuitable for diffraction-based velocity analysis, and any future drone surveys are benchmarked against ground-coupled datasets.