Fuzzy logic based traffic surveillance system using cooperative V2X protocols with low penetration rate

The penetration rate is one of the most important factors that affects the effectiveness of the mobile phone-based traffic state estimation. This article thoroughly investigates the influence of the penetration rate on the traffic state estimation using mobile phones as traffic probes and proposes reasonable solutions to minimize such influence. In this research, the so-called “acceptable” penetration rate, at which the estimation accuracy is kept as an “acceptable” level, is identified. This recognition is important to bring the mobile phone-based traffic state estimation systems into realization. In addition, two novel “velocity-density inference” models, namely the “adaptive” and the “adaptive feedback” velocity-density inference circuits, are proposed to improve the effectiveness of the traffic state estimation. Furthermore, an artificial neural network-based prediction approach is introduced to a the effectiveness of the velocity and the density estimation when the penetration rate degrades to 0%. These improvements are practically meaningful since they help to guarantee a high accurate traffic state estimation, even in cases of very low penetration rate. The experimental evaluations reveal the effectiveness as well as the robustness of the proposed solutions.

Low penetration rate is one of the essential issues in the mobile phone based traffic state estimation model. This paper proposes an appropriate genetic algorithm (GA) mechanism to optimize the traffic state estimation model even in cases of low penetration rate. This mechanism also reduces the critical penetration rate, thus improves the error-tolerance as well as the scalability of the traffic state estimation system. The paper also investigates the ANN-based prediction model to overcome the weakness of the GA-based traffic state estimation approach when the penetration rate becomes unacceptably low. In addition, the effect of different level related road segments on the prediction effectiveness is thoroughly discussed. Consequently, this study provides practically useful instructions in verifying the data missing rate at different level related road segments to ensure the prediction accuracy. The experimental evaluations reveal the effectiveness and the robustness of the proposed solutions.

A data fusion approach for real-time traffic state estimation in urban signalized links

A new synthetic-based Penetration Rate Enhancer designed as an environmentally acceptable alternative to terpenes is shown to be an effective treatment for increasing penetration rates by preventing or minimizing bit balling while drilling active shales prone to forming "gumbo". Both laboratory drilling simulator results and field case-histories are presented documenting the effectiveness of this chemistry and efficient techniques for application. The results show that this chemistry is effective with tri-cone bits but is more efficient with polycrystalline diamond cutter (PDC) bits and is particularly efficient when used with advanced design polished cutter bits with super sharp PDC cutters. Introduction Stagnant oil & gas prices coupled with escalating rig rates have placed an ever increasing premium on reducing drilling costs. The most significant component of the total drilling cost is typically the rig operating cost which makes drilling rate one of the key variable in determining a project's economic viability. One of the most significant developments toward maximizing penetration rates over the last 2 decades, particularly drilling shales, has been the introduction of PDC bits. These bits have set new penetration rate benchmarks when drilling shales, especially when used with oil and synthetic-based emulsion drilling fluids. PDC bits used with water-based drilling fluids have not performed nearly as well, especially in drilling deeper shales. The problem has proven to be so persistent that the Drilling Engineering Association formed cooperative research project DEA #90 in 1995 to investigate the causes. The initial findings of DEA 90, as released in Test Module #1, duplicated slow ROP scenarios seen in actual drilling operations. Low penetration rates with PDC bits in plastic shales, drilled at high bottom hole pressures with water-based drilling fluids were ascertained, along with mechanisms causing the slow penetration rates. PDC Bits and Shale PDC bits have traditionally been suited for drilling in shales. These bits become less effective, and possibly uneconomical, as certain shale types become stressed from increase in depth, mud weight, and cutter induced loading. Normally, PDC cutters easily shear shale as they drill. Shearing generates formation chips, which can be removed from under the bit face using conventional hydraulics. As the pressure stresses increase at depth, the formation becomes more plastic and requires different bit cutting mechanics to cut efficiently. This is accelerated as fluid density increases. Shale, and other ductile formations, tend to flow more easily at stress and thus conform to, and adhere more strongly, to surfaces they contact. In effect, the shear stress necessary to displace the cuttings from the face of a cutting element increases significantly under these conditions. It is believed that the shear stress required to displace a cutting from the face of cutter may be higher than the stresses necessary to shear the formation in front of the cutter. This phenomenon has been documented in the literature as a "built up edge". As the built up edge remains relatively stationary on the face of the cutting element, it becomes a tough, solidified agglomeration of formation, through shear enhanced compassion and hydration. The built up edge forms a very dull geometry, which hinders the performance of the cutting structure and results in unacceptable penetration rates. The concept of generating lower volume chips (thinner) and lower frictional forces on the cutter face, has proven to be a combination of technologies which significantly improves the drilling rate when drilling shales that typically result in low penetration rates. By polishing the surface of the diamond cutting element, the shear stress to displace the formation chip is drastically lowered. In addition, the rock strengthening effect that often occurs in front of a cutting element is avoided, allowing the formation to be failed at lower bit loads. It is also advantageous to concentrate the highest cutting stresses where the formation stress is initiated. P. 493^

Harder formations in geothermal and deeper oil and gas wells typically see lower rates of penetration (ROPs) and higher bit wear. Recent drilling experience in the Utah FORGE observed higher ROPs and longer runs using lighter drilling muds and new cutter technologies. Questions have arisen regarding reasons for the improved ROP and if the higher ROP is due to increased spurt loss or reduced hydrostatic pressure from lighter drilling fluids. A study was performed on an inhouse rig using two polycrystalline diamond compact (PDC) bits (4-bladed vs 5-bladed) to analyze the effect of confinement on ROP in Sierra White Granite (SWG). Tests were performed at confinements of 0, 1000, and 2000 psi and at constant rotational speeds of 80 and 150 RPM. Results show that when confinement is increased, ROPs are similar in the ineffective cutting Phase I. However, results in Phase II indicate that ROP is largely different between the unconfined and higher confinement testing. No significant effect on ROP is observed between 1000 and 2000 psi. At zero confinement, the 4-bladed bit outperformed the 5-bladed bit while at 1000 and 2000 psi confinement, the performance was similar. This paper presents the laboratory results with potential applications to hard rock geothermal drilling. INTRODUCTION Confining pressure in drilling terms is the hydrostatic pressure at the bottom of the well while drilling in impermeable formations. Many studies have outlined the effects of confining pressure on rock deformation but the effect of confinement on drilling efficiency and ROP is yet to be thoroughly investigated. In recent years, hard rock drilling especially in geothermal reservoirs has faced great challenges such as low penetration rates and high bit wear leading to high drilling costs. Advanced bit technology is required to maneuver the unique physical and mechanical properties of hard and abrasive rocks at high confining pressures. Although roller cone bits were predominantly used to drill hard and abrasive formations, PDC bits with enhanced cutter properties and ‘special’ cutter geometries are at the forefront of drilling research and technology. During the past years, new PDC cutter technology has improved cutter wear resistance and its capability to carry higher loads. Recent drilling experience in the Utah FORGE observed higher ROPs and longer bit runs using lighter drilling muds and new cutter technologies including shaped cutters (Dupriest and Noynaert, 2022). Glowka, (1985) discussed the potential for developing a PDC drill bit for hard rock applications such as geothermal drilling. Different cutter geometrical shapes and designs are currently being designed to address heavy impact damage in hard formations, prevent thermal damage and extend drilling runs while maximizing ROP. Zhu et al. (2022) analyzed the loading performance and rock cutting mechanism of different PDC cutters by using single cutter analysis to study geometry, aggressiveness, and stress distribution in granite. Xiong et al. (2022) studied the performance of a stinger PDC cutter in granite to evaluate cutting force and mechanical specific energy (MSE). Barnett et al. (2022) studied the effects of drillstring torsional vibration on ROP with PDC bits in hard rock. Wang et al. (2020) designed a PDC hybrid drill bit to navigate hard and abrasive formations. Akhtarmanesh et al. (2021) designed an ROP model for drilling hard and abrasive formations for PDC bits. It was seen that distinct phases of drilling exist where Phase I is the inefficient drilling phase due to insufficient WOB and Phase II is the efficient drilling phase due to higher WOB which results in a higher ROP. Figure 1 shows the different phases of drilling as described by Akhtarmanesh et al. (2021). Due to the complexity of drilling in hard formations, more testing is crucial to completely understand the effects of temperature, rock behavior, and confining pressure on ROP and bit cutting mechanism. An understanding of bit cutting action in hard rock is crucial for successful ROP optimization and improving drilling efficiency.

In the past, wells drilled in Crater field required an average of 310 days to reach total depth (TD), mainly because of operational problems, including drillstring twist-off, stuck pipe, unplanned sidetracks, excessive directional complexity when drilling, and under-reaming. Low rates of penetration (ROP) while drilling the Eocene and Paleocene intervals also impacted drilling time. Design optimization provided by a major service company allowed the operator to finish the recent Crater-52 well 95 days ahead of plan and 155 days ahead of the average duration for previous wells. This achievement significantly reduced operating costs and helped facilitate an anticipated production of 285,000 barrels of oil. Key achievements are summarized below: Drilled the 17.5-in. section 500 m deeper than the original design using 5.5-in. drillpipe instead of the traditional 5-in. Set 9.875-in. casing at the Medium Eocene Level, which made it possible to drill the 8.5-in. section with a much lower differential pressure, increasing ROP from 1 to 5 m/hr. Saved $3.4 MMUSD in operational costs and recovered 285,000 barrels of oil ahead of schedule. Reduced non-productive time (NPT) from 30% to 5.5%. Lithological characterization, calibration, and updating of the geo-mechanical model helped the operator drill 500 m deeper in the 17.5-in. section, which eliminated the need for hole enlarging in two problematic sections. Using 5.5-in. drill pipe improved hole cleaning, with faster ROPs as a direct consequence. Drilling the 12.25-in. section to the Medium Eocene made it possible to drill the 8.5-in. section with lighter mud weights, decrease differential pressure, and elevate ROP. Lost circulation risks were also minimized. The NPT was 83% lower than the field average. Based on these results, future Crater field well designs will also be optimized, and the drilling team is evaluating the feasibility of applying the optimized design in other fields. The improved hydraulics parameters helped increase hole-cleaning effectiveness and ROP while preventing operational incidents in the 17.5-in. and 12.25-in. intervals.

Compression is an essential aspect of real-time operations as the bandwidth of transmitted information is very limited during logging while drilling. Processing of nuclear magnetic resonance (NMR) data involves the inversion of echo trains (ET), which are compressed downhole and transmitted via telemetry. The performance of individual NMR ET compression techniques also needs to be evaluated on the input signal level because the comparison of inversion results is highly dependent on regularization. Improved compression is key to properly encoding and decoding rate of penetration (ROP)-dependent motion effects with the goal of improving the accuracy of NMR T2 distribution at increased ROP in real time. The value of information of an ET differs over its range. First, early echoes have a large impact on the total porosity. They require a large contribution to the computation of, i.e., root-mean-squared error, used for comparing compression techniques. Secondly, non-exponential motion artifacts have a non-negligible impact on the inversion for cutoff-dependent volumetrics with increasing ROP. We propose a logarithmic weighting of the error contribution when comparing different compression implementations. Principal component analysis (PCA) is a linear transformation and is, therefore, very robust. It can reduce the dimensionality of data even given highly clustered inputs. In a previous implementation of PCA, ROP motion effects were neglected in developing the basis set of vectors at the low ROP used in earlier drilling operations. However, neglecting ROP motion effects may have noticeable effects on inversion results for porosity and volumetrics at increased ROP. Therefore, new PCA basis vectors are developed to account for these motion effects. Parallel with the development of the enhanced PCA basis vectors, an alternative denoising and compression concept utilizing a neural network autoencoder was developed and evaluated. The autoencoder first encodes the input data to a lower-dimensional representation. The original input is reconstructed from this compact latent space encoding using a decoding block. The autoencoder is trained on a synthetic data set comprising different subsurface properties and acquisition parameters learning the salient features. With the aim of implementing the encoding block on a low latency/memory device downhole, optimization of the network topology involved both the size of the network and the accuracy of the decompressed signals for real-time NMR inversion. Validation of the PCA and autoencoder compression is performed using inverted volumetrics of the encoded and decoded ETs. A new PCA basis for NMR data compression was developed to properly encode and decode ROP-related motion effects. Its performance was compared to a conventional compression technique. In addition, results of a denoising and compression algorithm for NMR ET based on a fully connected neural network autoencoder are presented. Tests show an improvement in the axial motion effects introduced by increasing ROP. By using a weighted error metric to compare individual compression implementations, it is possible to focus on the value of information on the early echoes. Accounting for ROP motion effects in the development of a new PCA basis, as well as using the autoencoder in training, improves the inversion of movable and irreducible fluid components. In addition, a reduction in the amount of data to be transmitted allows for a further decrease in the telemetry footprint of the NMR measurement. Both approaches increase the amount of transmitted information while improving the evaluation of the subsurface environment.

This paper combines millimeter-wave radar (MMW) data with connected autonomous vehicle (CAV) trajectory data to estimate queue length on a second-by-second basis. Firstly, queued vehicles on multiple lanes with the same traffic movement are mapped to a virtual lane. Then, the presence of CAV or human-driven vehicle (HDV) for any given queueing index is determined. A Bayesian joint probability model is subsequently established for queue length expectation, considering the existence of the queued vehicle type as a condition. The average time headway and dissipation speed distribution are derived from departure timestamps, which allows for the calculation of the prior probability ratio of queue length. Lastly, the maximum likelihood estimation (EM) algorithm is employed for iteratively estimating the CAV penetration rate. Simulation results demonstrate the method offers a compelling trade-off between precision and second-based real-time performance, while field test results further confirm the wide applicability under various traffic conditions.

Contemporary traffic light control systems rely on sensors for detection of traffic which are costly in purchase, installation and maintenance. Emerging cooperative technology offers an attractive alternative where only one road side unit per intersection is required, instead of several infrastructure sensors per lane. However, studies showed that traffic control with cooperative detection requires a penetration rate of at least 20% to function effectively. To show the potential of cooperative traffic control, this study presents three algorithms: (i) the SWARM control algorithm, which is designed to work with very low penetration rates; (ii) an extension to the adaptive control algorithm, ImFlow, which uses cooperative data for enhanced queue modelling; and (iii) an ImFlow extension to stabilise green planning to enable green light optimal speed advice. The results from micro‐simulation show a 7.8% improvement for stops and delay time over traditional adaptive control for Swarm, and 14.9% for Cooperative ImFlow. Adding planning stabilisation reduced the average perceived change for end users from 9.0–2.3%, without performance loss for the overall traffic flow. This shows the large potential of cooperative traffic control.

Real time traffic states estimation on arterials based on trajectory data

Operators have expanded their search for new oil and gas reserves to more complex and challenging environments such as the ultradeepwater, presalt carbonate plays offshore Brazil. The major challenge these wells have faced historically is the well cost overrun from low rate of penetration (ROP) and downhole tool nonproductive time (NPT) related to drilling dysfunctions. To avoid costly trial and error, advanced software was combined with service provider and operator experience to get it right the first time: improving ROP while minimizing damage to the bottomhole assemblies (BHAs), drilling each section on time and on budget. An advanced 4D (spatial 3D + time) finite element transient drillstring dynamics modeling package is used to design the cutting structures, predict the drilling dynamics, evaluate different BHAs and drilling configurations, and optimize drilling parameters. BHAs for riserless, post-salt, salt, and silicified carbonate sections of the well are analyzed and optimized. Simulations are run to determine proposed BHA configurations and the potential for axial, lateral/torsional, and stick-slip vibration for different rock strengths. The BHAs are then optimized by adjusting cutting structure, stabilizer placement, hole enlargement ratio, and drillstring configuration. Once an optimum BHA is selected for each section, a sensitivity analysis is conducted on RPM, weight on bit, and torque to maximize ROP for each BHA. Three criteria are used to evaluate BHA performance: stability, robustness/reliability, and measurement quality. The performance of each optimized BHA is compared to the performance of the base case BHA from offset wells. The accuracy of the model's simulations and the optimum recommended parameters is also examined against field results. Overall, the optimized BHAs delivered up to 50% higher ROP compared to the base case from offset wells drilling similar formations. In most cases, the optimum parameters recommended by the model were also the optimum parameters in the field test. The increased confidence in the model from the field tests enabled its use to optimize the BHA further for future wells. This work presents a digital bit and drillstring design workflow, used to virtually run and analyze different BHA designs prior to running in the field. The work, tested in the field, resulted in multiple learnings shared in this paper, specifically in the realm of drilling mechanics.

The vehicles normally move at their free speeds when it is least impeded due to traffic flow under lean traffic (free flow) conditions. As traffic flow increases, the vehicles cannot sustain their free speeds due to interactions from other vehicles in the traffic stream. In addition to that the vehicles that are operating in the congested traffic conditions will consume more fuel than those operating in steady state traffic conditions for the same average speed. This leads to increase in travel time and fuel consumption of the vehicles and thereby adding to total road user cost (RUC). On the contrary, fuel consumption is also high at very high speeds under free flow traffic flow conditions leading to increase RUC. Considering these scenarios, the travel time and fuel cost of the vehicle due to the congestion and free flow conditions (uncongested) has to be necessarily modelled in order to estimate realistic assessment of RUC on Indian highways. In the present study, the congestion cost relationships have been developed between Congestion Factor, a ratio of cost under congestion and steady state conditions and Volume-Capacity Ratio by considering various vehicle types plying on varying widths of multi-lane highways (four, six and eight lane divided carriageways) through the collection of exhaustive time related and fuel related data. Time related data was collected through questionnaire survey method whereas fuel consumption data was collected using advanced sophisticated fuel flow measuring equipment (V-Box). The developed equations have been successfully applied to demonstrate their applicability in terms of estimating realistic effect of congestion on time and fuel cost by considering a section on NH-2 in Delhi. The analysis shows that the congestion effect is more significant on fuel cost for heavy commercial vehicles whereas it is more prominent on time cost for passenger vehicles. However, the congestion effect on combined fuel and time cost is more significant on multi-axle trucks followed by cars, two wheelers and buses.

An Engineered Geothermal System (EGS) pilot project was commissioned to prove the economic viability of an industrial scale geothermal heat plant in Finland. The project aims to generate 40 MW of emission free heat energy, supplying up to 10% of the city of Espoo’s district heating needs. Two wells of 6400 m MD and 6213 m MD (measured depth) were drilled through formations of hard, abrasive granitic gneiss with maximum measured 560 MPa UCS (unconfined compressive strength). Typical dull conditions of lost and worn cutting structure and gauge diameter wear of between 3/16-in to ¼-in contributed to excessive torque, stuck incidences, low rate of penetration (ROP) and difficulties achieving build rate. To address these drilling challenges, this paper explores the interplay between new cemented carbide compact technology, drill bit design, and drilling parameter road mapping. The directional section of the first well was drilled with an average ROP below 2 m/hr and run length averaging 56 m per bit. The well took 246 drilling days and 44 BHAs (bottom hole assemblies) to achieve TD (total depth). Between the first and second well an application specific drill bit design package and step-wise parameter program were implemented. Design enhancements included improved gauge protection, bit hydraulics for minimizing cone erosion and subsequent TCI (tungsten carbide insert) compact loss. Novel hybrid TCI materials technology was introduced having a 100% improvement in wear resistance and durability as compared with conventional grades, to drill these hard and abrasive granitic formations. New BHAs and drilling plan were selected based on the bit design selection to reduce wear on BHA components, improve directional control and reducing drilling dysfunctions. Once these factors were under control, a low risk approach to extending the bit revolution limits (krev) for the roller cone sealed bearings could be implemented based on downhole parameters and previous bit dulls, leading to longer run lengths. The combination of bit design and material enhancements with a properly selected BHA and drill plan increased run lengths and ROP. The second well’s 8.5-in directional section was drilled with a 13% increase in average ROP and a 69% increase in average run length without exceeding krev limits. Well on well, a 77 day reduction in AFE (authorization for expenditure) was realized. We demonstrated the combination of oil and gas bit and BHA design, drilling plan, and new cutting material capabilities can reduce EGS well construction costs in order to make these renewable energy sources economical.

Variable speed limits (VSLs) have a potential to improve mobility and safety of motorway through harmonisation of traffic flow. However, the success of VSL is highly dependent on drivers’ compliance to the displayed speed limits. Emerging technologies in the field of connected autonomous vehicles (CAVs) is likely to revolutionise the way VSL will be operated in the near future. VSL can be integrated with CAVs where CAVs will automatically obey the displayed speed limits. However, 100% penetration rate of CAVs is a long‐term goal. At the initial stage of deployment, CAVs will coexist with manually driven vehicles on motorways. This study explores ways to implement VSL under a mixed traffic condition where CAVs and manually driven vehicles coexist in the traffic stream. A hybrid approach combining particle swarm optimisation with proportional‐integrated‐derivative is proposed to improve VSL implementation under a range of mixed traffic conditions. The simulation results showed that the proposed method successfully achieved the desired speed limits and rapidly stabilised the system at the initial and transient points at penetration rates of 50 and 75%, whereas the method encountered serious overshoots at lower penetration rates.

The well construction operation in the pre-salt reservoirs of Santos basin faced great challenges such as the drill string stuck in big-thickness salt formation (more than 2000m) and low penetration rate in the reservoir formation from the beginning of X. Project. The average actual well construction duration of four wells completed in 2015 was 7 days behind the planed period caused by the above-mentioned problems. The well construction cost was more than the approved budget due to the delayed well construction duration. So efforts was concentrated to integrate drilling technology in ultra-deep water to solve drilling challenges in the pre-salt reservoirs to decrease well construction duration and increase exploration and development benefit. This paper presents an integrated drilling technology to solve drilling challenges in pre-salt reservoirs of ultra-deep water. The combination of near bit reamer stabilizer and synthetic-based mud can prevent the salt formation creeping and decrease the drill string stuck frequency. The optimization of drilling parameters based on mechanical specific energy concept can clearly identify the transfer from the anhydrite formation to the salt formation and drilling penetration rates can be improved in salt formation by optimizing WOB, rotate speed and pump rate, etc. The combination of MPD, turbine drill and impregnated bit can control the mud losses and increase the penetration rates in the carbonate reservoirs which possess poor drillability. All the above-mentioned drilling technology has been applied in two wells and successfully solves the drilling challenges in the pre-salt reservoirs of X. Project. The combination of near bit reamer stabilizer and synthetic-based mud has decreased the drill string stuck NPT from 11.7d to zero in two wells of X. Project. The average ROP record of the two wells by use of the integrated drilling technology is 24.6 m/h that has been improved 3.4 times comparing the completed four wells in 2015. The drilling duration for 2062m salt section has decreased to from 14 days to 7 days which saved about 14 millions dollars for the two wells. The average ROP in the reservoir formation of the two wells has been increased to 3.45m/h which was about 1.5 times of the four wells' average ROP completed in 2015. The reservoir section has been completed 4.6 days ahead of the planed duration and the comprehensive drilling cost has been saved 5 millions. The integrated drilling technology in pre-salt reservoirs in ultra-deep water made the average well construction duration of the two wells finished in 2016 have decreased to 111 days, however, the average well construction duration of the four wells completed in 2015 was 162 days. The fastest record of the one well's construction duration was 76 days establishing a new benchmark in pre-salt reservoirs in ultra-deep water. The method to solve well construction challenges in the pre-salt reservoirs of Santos Basin of this paper presented will make a reference for deep water salt formation drilling and offshore oilfields high efficiency development.