Drilling Tests Research Articles

Modeling Evolution of Cutting Force in Ultrasonically Assisted Drilling of Carbon Fiber Reinforced Plastics.

In this study, the effects of process parameters (feed rate, spindle speed, and ultrasonic power level) on the cutting force and delamination in the ultrasonic vibration-assisted drilling of carbon fiber-reinforced plastics (CFRPs) have been investigated. A series of drilling tests under various conditions defined by the design of experiment technique were conducted. The evolution of the cutting force during drilling cycles was measured and analyzed. Experimental analysis results based on the Taguchi method and analysis of variance show that the spindle speed is an influential factor affecting the cutting force with a contribution of 75.36%, and the feed rate significantly affects the delamination damage with a contribution of 46.57%. In addition, the cutting force was found to increase with drilling cycles at different rates, which depends on the process parameters used in drilling. The evolution behavior of cutting force was well fitted based on the process parameters by proposed regression models. Experimental validation indicates that the predicted forces show reasonable agreement with measured values under different conditions and reveal good prediction performances, with a root mean square error of 5.6 and a mean absolute percentage error of 5.8%. In drilling tests with variable cutting conditions, the evolution of the cutting forces predicted based on the selected parameters was successfully verified when compared with the measured results, with RMSE and MAPE values of 7.55 and 5.61%, respectively. As a conclusion, this predictive model provides an effective basis for selecting appropriate drilling parameters to suppress the cutting force on CFRP composites.

Characterizing the non-Newtonian viscosity of high-solids drilling fluid dispersions by flow loop

Increasing the speed of drilling operations is of commercial and military interest for transportation infrastructure as well as rapid installation of underground utilities in urban settings and over long distances. A significant challenge to increasing speed in horizontal directional drilling is pressure and flow rate management of drilling fluids circulating into and out of the borehole, removing solids cut free by the drill bit. The mixture of solids and drilling fluid results in a highly complex fluid dispersion, typically with a shear-thinning continuum. It is challenging to characterize the viscometric behavior of these dispersions, and such data are limited in the literature. It is increasingly important to understand and accurately model the viscosity of these dispersions since high drilling speeds increase the drilling fluid flow rate, approaching the pressure limits that borehole walls can withstand before failure. In this work, we characterize the viscometric properties of a drill test and model drilling fluid dispersion in a custom-built flow loop with solid concentrations up to 45 wt. %. The fluid viscosity is reported in terms of power-law parameters, which can be used to predict the pressure drop during real drilling conditions. We found a significant difference in the viscometric response between the drill test and model drilling fluid dispersions. The Shields parameter can capture the influence of solids settling on the measurable pressure losses. An important conclusion is that even model drilling fluid dispersions prepared with geotechnical data from a drill site may have significantly different viscometric characteristics than those relevant during a drilling operation.

Experimental Investigation on the Energy Consumption Difference between the Dynamic Impact and the Drilling Tests of Rocks

The split Hopkinson pressure bar (SHPB) technique and various drilling tests were performed on three types of lithologies (granite and cyan and red sandstone) to understand the variation in energy consumption (EC) of the different methods used for rock crushing. The dynamic behavior of rocks was analyzed based on the dynamic stress-strain curve, the peak stress, the energy, and the failure mode for the SHPB test, while the drilling curve, the influence of the drilling pressure (DP) and the revolution speed (RS) on the drilling speed (DS) were analyzed for the drilling test. Additionally, the EC difference was compared based on the EC required to break a single unit volume of rock. The obtained results indicate that the sensitivity of the dynamic strength of rocks with different lithologies to strain rate is different and that the higher the uniaxial compressive strength is, the more sensitive it is. Additionally, the strengthening of the peak stress is more pronounced with the increase in the strain rate. The energy utilization efficiency (EUE) of the SHPB test sample has a positive correlation with the strain rate. Moreover, the typical drilling process can be divided into the initial drilling and stable drilling stages, with the DS during the stable drilling stage being lower than that during the initial drilling stage. The DP and the RS have a linear positive correlation with the DS, with the influence of the DP on the DS being more obvious. Finally, the EC during the drilling process is higher than the EC during the SHPB technique.

Scientific Results of the Hydrate-01 Stratigraphic Test Well Program, Western Prudhoe Bay Unit, Alaska North Slope

The United States Department of Energy, the MH21-S Research Consortium of Japan, and the United States Geological Survey are collaborating to enable gas hydrate scientific drilling and extended-duration reservoir response testing on the Alaska North Slope. To feasibly execute such a test, a location is required that is accessible from existing roads and gravel pads and that can be occupied without disrupting ongoing industry operations. A review of potential locations meeting these criteria determined the likely occurrence of gas hydrate in two fine-grained marginal-marine sands of Tertiary age in the vicinity of the inactive “Kuparuk State 7-11-12” exploration pad in the western Prudhoe Bay Unit (PBU). Existing well and seismic data for that site were insufficient to preclude the potential for free gas occurrence within the deeper (and most prospective) target sand. Therefore, with support from the PBU Working Interest Owners, Alaska Department of Natural Resources, and Petrotechnical Resources Alaska, the Hydrate-01 Stratigraphic Test Well (STW) was drilled in December 2018 to confirm the suitability of the site for future gas hydrate scientific testing. The Hydrate-01 well was successfully drilled to −3290 ft (1003 m) subsea vertical depth at a bottom hole location of approximately 900 ft (∼275 m) east of the surface location. The drilling program featured acquisition of a full suite of logging while drilling data, the collection of side-wall pressure cores, and the installation of distributed temperature and distributed acoustic sensor fiber-optic cables. The log data acquired confirmed the occurrence of gas hydrate at high saturation in two target sands. Integrated evaluation of log and sidewall core data provide petrophysical and geomechanical property information that allow for potential reservoir response to depressurization to be simulated. The deeper “B1 sand” is deemed to be most favorable for reservoir response testing as a result of confirmed gas hydrate occurrence in sediments of high intrinsic permeability, location within 100 ft (30 m) of the base of gas hydrate stability, and minimal risk for direct communication with permeable water-bearing (hydrate-free) zones. The shallower “D1 sand” provides a secondary target that is differentiated by colder in situ temperatures and the interpreted direct hydraulic communication to a lower section of non-hydrate-bearing, water-saturated sand. The Hydrate-01 log data also confirm the occurrence of at least one sub-seismic fault in close proximity to the B1 sand reservoir. To better image the distribution of the gas-hydrate-bearing reservoir sections and associated faults, a three-dimensional (3D) vertical seismic profile was conducted in early 2019 using the distributed acoustic sensors installed as part of the Hydrate-01 STW completion. Detailed two-dimensional (2D) and 3D geologic models have been constructed to enable numerical simulations to inform the planning for potential future scientific tests of reservoir response to depressurization at the site.

Modeling and Dynamic Performance Analysis of Hydraulic Top Drive Main Transmission System with Long Hydraulic Pipelines

Hydraulic top drive is the main power component used to drive drilling tools rotating to drill a hole for drilling rigs. Its main transmission system was built with hydraulic power source and hydraulic actuators. During the drilling procession, the hydraulic top drive is mounted on a derrick, and moving along its vertical guide rails. The hydraulic power station is usually placed on the drilling platform or the ground. In that way, long pipelines are needed to connect the hydraulic pumps and hydraulic motors. Thus, the effects on the performance of hydraulic top drive should not be neglected. A mathematical model of hydraulic top drive main transmission with differential equation of hydraulic units and state space equation of hydraulic long pipelines was deduced in this research. A simulation model was built using the AMESim software. And field drilling test of the hydraulic top drive was carried out in Songliao Basin Drilling Project (SK-II) well site. To verify and modify the virtual model, a comparison analysis was performed by setting the parameters and load of the three methods at the same values. The result of comparison shows that the simulation results are very close to the theoretical results and field drilling test data. Thus, the dynamic characteristics could be analyzed by this simulation model. Dynamic characteristics of the hydraulic top drive with different length and various diameters of pipelines were studied. The simulation results demonstrate that pipeline lengths and pipeline diameters affect the system in different laws, and it needs to comprehensively consider the system response speed, overshoot, and steady-state characteristics when choosing the size of pipelines for hydraulic top drive.

Evaluation of different methods for deriving geotechnical parameters from electric and seismic streamer data

Geotechnical parameters of linear earth structures, such as embankments and earth dams, are usually obtained from point-wise investigations through drilling or penetration tests, commonly time and cost consuming. Non-invasive geophysical investigations can be considered alternative for a preliminary screening of earth structures physical properties, given their surveying speed and their depth and length of investigation. Seismic and electrical methods can be also used, through specific correlations, for the estimation of geotechnical soil characteristics. Several methodologies have been developed over the years combining two or more geophysical techniques for the estimation of geotechnical parameters.In this paper, data from geophysical surveys were used for the comparison of geotechnical parameters forecasted with three different methods (with theoretical, statistical, and field based approaches respectively). Their strongpoints and limitations were also evaluated by comparison with available direct geotechnical investigations.Integrated seismic and electrical data from extensive surveying performed over seven retaining structures located in Piedmont Region (NW Italy) were used to forecast their fine content and hydraulic conductivity distributions. Geophysical data were acquired using seismic and electric streamers, useful for the simultaneous execution of the surveys in motion along the earth structures. The results of this study show the effectiveness of the proposed data acquisition approach and elaboration procedures as a first screening tool for earth retaining structure safety assessment. The increased capability of the theoretical method to better predict geotechnical parameters with respect to the other methodologies is also reported.

Machinability of alloy ductile iron and forged 16MnCr5 steel

Abstract The remarkable mechanical properties of austempered ductile iron (ADI) render ADI as an alternative material for forged steels. On the other hand, the high strength and hardness make the machining of ADI to be challenging. In this study, the ADI is presented as an alternative material to fabricate the ring gear of the two-wheel tractors. A series of experiments were designed to evaluate the machinability of the alloyed ductile iron before the austempering process. 16MnCr5 alloy steel and alloyed ductile specimens were subjected to drilling tests. The effect of drilling parameters on thrust force was investigated based on a design of experiments approach. A regression model was established to predict thrust force at various drilling conditions. Then, the machinability rating was defined as the ratio of the predicted thrust forces. The results showed that at lower feed rates, the thrust force is very close for both materials, such that the estimated machinability rating is 86%.

Optimisation of drainage performance of the thin-walled core barrel sealing technology for pressure preservation sampling

Pressure preservation sampling technology is a crucial method to assess natural gas hydrates. There are limitations to directly applying conventional pressure preservation technology for seafloor drills, such as large and complex structures. The working and design principle of the thin-walled core barrel sealing technique is introduced. To solve the problem of low core recovery percent during sediment drilling, the flow field characteristics of the valve spool in different working conditions are discussed. The area of the cross-section and the calculation method under the typical position are obtained. The valve spool structural parameters are determined and verified by a laboratory drilling test. The results show that: the larger the cone angle of the spool or the smaller the percentage of valve spool cone height to valve spool full cone height (the following is called P), the smaller the opening value when the cross-section area reaches a stable level. When the cone angle is 30, and the P is 20%, the cross-sectional area reaches stable after the opening is 4.5 mm. When the opening exceeds 3.0 mm, the flow rate changes little. When drilling in the sediment, the average coring recovery percent exceeds 70%.

Compilation of drilling load spectrum based on the characteristics of drilling force

In order to overcome the problem that the existing methods of compiling load spectrum of spindle or machine tool mainly aim at the cutting force spectrum, torque spectrum and speed spectrum, respectively, which ignore the connection between each spectrum, in this paper, a method for compiling drilling load spectrum of motorized spindle in CNC machine tool based on the characteristics of drilling force is proposed. Firstly, drilling tests under different processing technologies are carried out to measure its load, and the correction coefficient in the empirical formula of drilling force is obtained through fitting the measured drilling force, which makes the calculation of the axial force and torque more reasonable. Secondly, compared with the extended factor method, the transcendental probability method is optimized to solve the ultimate load of the axial force. Then, after setting the axial force as the main load of drilling, an eight-stage load spectrum for the main load is compiled. Finally, according to the relationship between the axial force and other loads, the eight-stage loading spectrum is transformed into a multidimensional drilling load spectrum.

Planning and Operations of the Hydrate 01 Stratigraphic Test Well, Prudhoe Bay Unit, Alaska North Slope

The National Energy Technology Laboratory, the Japan Oil, Gas and Metals National Corporation, and the U.S. Geological Survey are leading an effort to conduct an extended gas hydrate production test in northern Alaska. The proposed production test required the drilling of an initial stratigraphic test well (STW) to confirm the geologic conditions of the proposed test site. This well was completed in January 2019 in cooperation with the Prudhoe Bay Unit Working Interest Owners. The Prudhoe Bay Unit Hydrate-01 STW was spudded on 10-December-2018. Downhole data acquisition was completed on 25-December-2018, and the rig was released on 01-January-2019. The Hydrate-01 STW was drilled in two sections, including the surface hole that was drilled to a depth of 2248 ft measured depth (MD) (685 m MD) and cased, and the production hole section that was drilled to a depth of 3558 ft MD (1084 m MD) and also cased. A thermally chilled mineral-oil-based mud was used in the main (production) hole section of the well to maintain wellbore stability and quality of the wellbore acquired data. The primary wellbore data were acquired using logging-while-drilling tools. A sidewall pressure core system was also deployed to gather grain size and other data needed for the design of the future production test wells. In addition to confirming the geologic conditions at the test site, the Hydrate-01 STW was designed to serve as a monitoring well during future field operations. Therefore, two sets of fiber-optic cables, each including a bundled distributed acoustic sensor (DAS) and a distributed temperature sensor (DTS), were clamped to the outside of the production casing and cemented in place. In March 2019, the project team acquired three-dimensional (3D) DAS vertical seismic profiling data in the Hydrate-01 STW. Temperature surveys were also acquired with the DTS as deployed in the Hydrate-01 STW during the completion of the well and nearly continuously since March-2019.

Regressive and Big-Data-Based Analyses of Rock Drillability Based on Drilling Process Monitoring (DPM) Parameters

Accurate, rapid and effective analysis of rock drillability is very important for mining, civil and petroleum engineering. In this study, a method of rock drillability evaluation based on drilling process monitoring (DPM) parameters is proposed by using the field drilling test data. The revolutions per minute (N), thrust, torque and rate of penetration (ROP) were recorded in real time. Then, the two-dimensional regression analysis was utilized to investigate the relationships between the drilling parameters, and the three-dimensional regression analysis was used to establish models of ROP and specific energy (SE), in which the N-F-ROP, N-T-ROP and the improved SE model were obtained. In addition, the random forest (RF) and support vector machine combined with genetic algorithm (GA-SVM) were applied to predict rock drillability. Finally, a prediction model of uniaxial compressive strength (UCS) was established based on the SE and drillability index, Id. The results show that both regression models and prediction models have good performance, which can provide important guidance and a data source for field drilling and excavation processes.

Deep convolutional neural network for multi-level non-invasive tunnel lining assessment

In recent years, great attention has focused on the development of automated procedures for infrastructures control. Many efforts have aimed at greater speed and reliability compared to traditional methods of assessing structural conditions. The paper proposes a multi-level strategy, designed and implemented on the basis of periodic structural monitoring oriented to a cost- and time-efficient tunnel control plan. Such strategy leverages the high capacity of convolutional neural networks to identify and classify potential critical situations. In a supervised learning framework, Ground Penetrating Radar (GPR) profiles and the revealed structural phenomena have been used as input and output to train and test such networks. Image-based analysis and integrative investigations involving video-endoscopy, core drilling, jacking and pull-out testing have been exploited to define the structural conditions linked to GPR profiles and to create the database. The degree of detail and accuracy achieved in identifying a structural condition is high. As a result, this strategy appears of value to infrastructure managers who need to reduce the amount and invasiveness of testing, and thus also to reduce the time and costs associated with inspections made by highly specialized technicians.

The Effect of Skipping, Ground Ladder and Line Drill Trainings on Speed, Agility and Coordination in Basketball Players

Aim: The aim of this study is to investigate the effects of intensive skipping, line drill and ground ladder training on speed, agility and coordination in order to increase the performance of athletes during the short camp period. Methods: The study group was selected from among 3000 athletes determined as a result of the screenings covering 81 provinces for the Turkey men's star national basketball team. 92 athletes who passed the first stage, which consisted of physical characteristics and pre-test evaluations, participated in the study. In addition to general basketball training, young basketball players were given intensive skipping, line drill and ground ladder exercises for 15 days. The average age of the basketball players participating in the study was 15,52,5 years, height 185,015,9 cm, and body weight 75,223,6 kg. In the study, 30 meters, illinois agility, hexagonal (coordination) and T Drill tests were used to determine the speed, coordination and agility of basketball players. Results: While no significant difference was found in the 30 meter Speed Test values of the basketball players in the study, a statistically significant difference was found in the Illinois Agility Test, T Drill Agility Test and Hexagonal Coordination Test values. As a result, it was concluded that the intense skipping, ground ladder and line drill trainings during the short camp period did not improve speed, but the agility and coordination of the athletes significantly improved. Conclusion: In the light of these results, it can be said that it would be appropriate for the athletes to have skipping, ground ladder and line drill trainings in order to improve agility and coordination during the short camp period.

Subsurface seismic imaging with a hammer drilling source at an exploration drilling test center in Örebro, Sweden

Abstract. Seismic imaging while drilling (SWD) technology offers possibilities of imaging ahead of the drill-bit, which could be useful for determining when to go from hammer drilling to core drilling. Also, seismic images of the surrounding rock can improve geological models which could be then used to guide drilling programs. An SWD field test was carried out in August 2020 at an exploration drilling test site in Örebro, Sweden, with the aim to determine if the signals from hammer drilling can be used for seismic imaging around the drill-bit in a hard-rock environment where the strong drill-rig noise interference is one of the main challenges. The test site had previously been investigated with various geophysical methods, geological mapping and diamond core drilling, and it therefore represented an ideal location to perform this feasibility study. After data pre-processing and cross-correlation with the trace from the geophone closest to the rig, the shot-gathers were vertically stacked over the length of a drill pipe to achieve further signal improvement. A comparison with the active seismic data shows reasonable agreement, in spite of the fact that the noise level is significant even after careful processing. However, the lack of clear reflections in the active seismic data, indicating no detectable changes in the bedrock lithology in the near surface, hinders the full assessment of the seismic signal generated with hammer drilling at this site.

In-situ investigation of drilling performance and bit wear on an electrical drill hammer

Estimation of drillability is very important in rock drilling. Drilling performance and tool wear are two indispensable parameters for time and cost evaluation of an operation. In this article, by using an electrical drill hammer and two types of drill bits, in-situ drilling tests were conducted on three rock types to estimate the drilling performance and tool wear. Experimental results showed that the highest performance and the greatest bit wear occur in drilling sandstone, while the lowest values of penetration rate and wear are observed in amphibolite and basalt. Moreover, the penetration rate of drilling is related to rock mechanical properties. Regression analysis indicated that the correlation of performance with uniaxial compressive strength, Brazilian tensile strength and point load index, respectively, is significant and reliable. Regarding to the tool wear, equivalent quartz content showed a reasonable correlation with bit wear, compared to Cerchar abrasivity index and LCPC abrasivity coefficient.

Effects of Trace Elements on the Microstructural and Machinability Characteristics of Al–Si–Cu–Mg Castings

This study was undertaken to emphasize the influence of Sn and Bi addition on the machinability of Sr-modified, grain-refined, and heat-treated Al–Si B319 and 396 alloys. Drilling and tapping tests were conducted to examine the cutting forces, tool life, tool wear, built-up edge evolution, and chip shape. Microstructures were examined using optical and electron microscopy. Drilling test results show that the B319.2 alloy with 0.15%Sn yields the longest drill life, i.e., twice that of the B319.2 alloy containing 0.5%Bi, and one-and-a-half times that of the B319.2 alloy containing 0.15%Sn + 0.5%Bi. The presence of 0.5%Bi in the B319.2 alloy causes a deterioration of drill life (cf., 1101 holes with 2100 holes drilled in the B319.2 alloy containing 0.15%Sn). The α-Fe phase in the 396 alloy produces the highest number of holes drilled compared with alloys containing sludge or β-Fe. The presence of sludge decreases the drill life by 50%. Built-up edge (BUE) measurements and optical photographs show little change in the BUE width for different numbers of holes except for the B319.2 alloy containing 0.5%Bi, which shows a slightly lower width (0.166 mm) compared with that containing 0.15% Sn (0.184 mm) or 0.15%Sn + 0.5%Bi (0.170 mm).

Geophysical Research on Rock Mass Quality Evaluation for Infrastructure Design

AbstractEvaluation of rock mass quality is necessary for the proper design of engineering infrastructures. Rock quality designation (RQD) is an important geotechnical parameter in the rock mass quality classification. However, given the limited data and natural heterogeneity, rock mass quality evaluation is a challenging task. Traditionally, the rock mechanical parameters are obtained from the drilling tests. However, the drilling tests only provide single‐point information and thus cannot provide detailed underground information. Moreover, boreholes are costly and time‐consuming, and still cannot be carried out in the steep topographic terrains. Alternatively, electrical resistivity tomography (ERT) is non‐invasive, cost‐effective, and user‐friendly, can provide 2D plane information even 3D information, and can bridge gaps between the available well data and the accurate subsurface geological model. In this research, we establish important empirical relations between ERT and the limited borehole data. We estimated RQD along with the ERT profiles and evaluated the subsurface for rock mass quality even where no borehole exits. Furthermore, the ambiguity of water/clay distinction in the geological model was removed via integration between ERT and induced polarization. Compared with the past geotechnical studies, our work provides far better insights into the subsurface via 2D/3D evaluation of rock mass quality for the development of the engineered structures. Therefore, geophysical research based on ERT can be very helpful in the hard rock terrains lacking sufficient mechanical well data.

Effect of Various Microstructures Obtained from Heat Treatment on Machinability Behavior of Ti-6Al-4V Alloy

Drilling test on cylindrical work-pieces was carried out to analysis effect of various microstructures resulting from heat treatment on the machinability of the Ti-6Al-4V alloy. Chip morphology plays a predominant role in determining machinability and wearing of a tool during the drilling of titanium alloys. For this purpose, Ti-6Al-4V was heat treated in three variant cycles then drilled by 2mm diameter drill at 18.8 m/s speed and 0.1 mm/rev feed rate. Results show that heat treatment can effect on hardness. The SEM results showed that by changing their phase and morphology obtained from diferent heat treatment cycle, the machining conditions change. Increasing hardness led to increases length of spiral chips that indicate easy drilling. At a lower depth of cutting, ribbon chips are more compacted in comparison with samples which have a lower hardness. Drilling temperature was increased by increasing deep hole. Samples with lower hardness had a higher temperature in drilling.

Geochemistry and sources of hydrate-bound gas in the Shenhu area, northern south China sea: Insights from drilling and gas hydrate production tests

Research on the origin and source of hydrate-bound gas and its relationship to deep conventional oil and gas accumulation in a basin is critical to understanding the accumulation mechanism of gas hydrates and to resource evaluation of gas hydrate accumulation. In this study, the hydrate-bound gas obtained via pressure coring and the production gas recovered during a production test on a gas hydrate reservoir in the Shenhu area offshore of Southern China were tested and discussed. The geochemical analysis results indicate that methane is the predominant gas, and heavier hydrocarbons (C2+) are also present but in low concentrations. The molecular compositions of the hydrate gas recovered from two production test sites are similar to those of the hydrate-bound gas acquired via pressure coring. In addition to the isotopic composition of the methane, the carbon and hydrogen isotopes of the C2+ hydrocarbons were obtained for the first time. The δ 13 C isotopes of the methane range from −66.6‰ to −46.2‰, indicating that the hydrate-bound gases have a mixed origin, containing both biogenic and thermogenic gases. The plot of δ 13 C 1 versus δ 13 C 2 suggests that the biogenic and thermogenic hydrocarbons were derived from marine organic matter and terrestrial organic matter, respectively. The isotopic characterization of the hydrate-bound gas reveals that the thermogenic hydrate gas contains both humic-type gas and sapropel-type gas, but the sapropel-type gas is predominant. The source rocks of the thermogenic hydrate gas are interpreted to be both the gas-prone coal measure strata of the Enping Formation and the oil-prone medium-deep lacustrine strata of the Wenchang Formation, the latter of which contributed more to the hydrocarbon supply of the gas hydrates. In addition, the maturity of the source rocks of the thermogenic hydrate gas may be lower than that of the deeply buried conventional hydrocarbons discovered in the Baiyun Sag-Panyu Low Uplift area. The seismic profile crossing the shallow gas hydrate accumulations and deep conventional gas reservoirs clearly shows that the proven LW3-1 thermogenic gas reservoir communicated with the gas hydrate stability zone through vertical migration pathways formed by high-angle faults and gas chimneys. This indicates that there was a cogenetic relationship between the thermogenic hydrate gas and the deep conventional hydrocarbon reservoir, which was supplied the thermogenic gas derived from both the Wenchang and Enping formations. The major implications of this finding are that it confirms, rather than theorizes, the identity of the hydrocarbon source rocks of the thermogenic hydrate gas in the Shenhu area for the first time, and it demonstrates the coupling relationship between the shallow gas hydrate accumulations and the deep conventional reservoirs proposed in previous studies. The mechanisms of hydrocarbon migration and gas hydrate accumulation in the production test gas hydrate reservoirs in the Shenhu area were also identified, providing a valuable reference for subsequent exploration and for the potential exploitation of gas hydrate reservoirs in the South China Sea. • The δ 13 C and δD isotopes of the heavier hydrocarbons (C2+) in the Shenhu area are obtained for the first time. • The origin of the hydrate gas obtained from the second trial production well in the Shenhu area is confirmed. • The hydrocarbon source rocks of the thermogenic hydrate gas in the Shenhu area are identified. • Coupled paragenetic relationship between shallow gas hydrate and deep petroleum system is revealed.

The influence of nutrition education intervention combined with FIFA11+ program on physical fitness attributes, physical activity behaviors, eating habits and nutritional knowledge in young basketball players

The aim of this study was to analyze the effects of a nutritional education program combined with the FIFA 11+ program on physical fitness attributes, physical activity levels, food and nutritional habits and nutritional knowledge in young basketball players. Twenty-three under 14 elite basketball players (13 males and 10 females) belonging to a professional basketball academy participated in the study. Physical fitness attributes (countermovement jump [CMJ], drop jump[DJ], linear sprint, Lane Agility Drill, 505 change-of-direction, and repeated-change-of-direction [RCOD]), physical activity levels (Physical Activity Questionnaire for Adolescents, PAQ-A), eating and nutritional habits (Turconi questionnaire), and nutritional knowledge (modified version of the Turconi questionnaire) were assessed before and after the five months intervention period. Participants were involved in five nutrition education sessions and in a weekly session of the FIFA 11+ program. Pre-to-post differences revealed improvements in physical fitness attributes (i.e., CMJ, Lane Drill Test and RCOD time test [p < 0.05; effect size (ES) = 0.52 to -1.68]) and physical activity behaviors (PAQtotal and PAQ Lunch [p < 0.001; ES = 0.68-0.89]), as well as a maintenance of eating and nutritional habits and nutrition knowledge. In practical terms, the usual on-court and the implementation of nutrition education interventions combined with the FIFA 11+ improve physical fitness attributes and physical activity behaviors while favor the maintenance of eating and nutritional habits and nutrition knowledge in U14 elite basketball players