Drilling Time Research Articles

A time-optimal wellbore trajectory design for slide drilling systems

For decades, the slide drilling system (SDS) has played a critical role in the area of directional drilling. Drilling in the sliding mode is much more time-consuming than drilling in the rotating mode for a SDS. Therefore, it generally takes more time to drill a curved wellbore segment than a straight segment of the same length. Based on this fact, a novel wellbore trajectory design for SDSs is proposed in this paper to reduce the total drilling time and improve economy. The basic idea of our strategy is to replace a long curved wellbore section, e.g., the build-up and drop-off sections, with a series of short circular-arc and straight-line segments in the design stage. Assuming that rotating and sliding modes are only used for straight-line and circular-arc segments, respectively, the total drilling time is reduced by increasing the average rate of penetration. Therefore, the problem lies in how to replace a long circular arc with multiple short circular arcs and straight lines to minimize the total drilling time, which is the aim of this research. In this paper, a piecewise trial strategy is proposed, where the optimized wellbore trajectory is generated by adding circular-arc and straight-line segments with equal length one by one according to the “line first” principle. This strategy converts the original optimization problem, which involves both combinatorial and parameter optimization of unknown dimension, to a much easier one, where there are only three design variables and one set of constraint equations. Due to the multimodal characteristics of the objective function, genetic algorithm (GA) is adopted to obtain the optimal solution. A great reduction of the drilling time is obtained by applying our method to two typical cases, which shows a clear potential for future field applications.

Product Mix Optimization for an Oil Field Operating Company

In this study, a mathematical model is formulated to select the optimal product mix of wells in terms of numbers and types of wells that helps to maximize profit. The optimization model comprises two main components, the first component is revenue which includes forecasting of production and oil price, and the second component is cost which includes capital and operating costs. In addition, the model considers all related constraints such as budget, production targets, surface facility limitations, drilling rigs availability and others. Time has influence on the model, since its output is not limited only to the types and numbers of wells to be drilled during the planned period, but also when each well to be drilled for the same plan. Actual planning data for three consecutive years is used for model testing. The results show that 42% to 47% cost saving can be achieved by using the model. The analysis shows that with every 10% increase in oil price, the profit increases by about 6%. Also, it shows that the number of rigs and the rig daily cost affect the profit tremendously, where by reducing these two parameters by 50% an increase of 66% in oil profit can be achieved. The study confirms that oil field operating companies can stand a better chance of maximizing their profit by using product mix optimization model to define the optimum schedule for the number of wells, type of wells and time of drilling.

Cost-effectiveness of Tunnel Blasting Pattern by Applying Large Blasting Holes

The research is carried out to analyze the cost-effectiveness of blasting patterns with regard to the diameters and design of blasting holes. Blasting patterns for single diameter array, and mixed diameter array were comparatively analyzed with regard to drilling and charging time, and materials required. The number of blasting holes required for single array pattern and mixed array pattern were 138 and 93 holes, respectively. From the drilling time analysis, reduction in time and its efficiency of mixed pattern were 139 minutes and 25%, respectively, in comparison with single pattern. Charging time reduction and its efficiency of mixed blasting pattern were evaluated as 22.5 minutes per worker and 33%, respectively, compare to single blasting pattern. The explosive quantities of G1 and G2 required for single array patterns were 270 and 30, while those were 222 and 20 for mixed array patterns for tunnelling 4m. And single pattern required 45 more detonators than the mixed pattern. The evaluation of material required can also be positive parameter for cost reduction of tunnel construction.

Excess Air Correction of SF6 and Other Dissolved Gases in Groundwater Impacted by Compressed Air From Drilling or Well Development

AbstractAtmospheric gases that dissolve in groundwater at the time of recharge are valuable tracers of groundwater residence time, but corrections are sometimes required. Low‐solubility gases like SF6 are particularly susceptible to the effects of excess air, which is generally assumed to occur at the time of recharge. If after excess air correction SF6 is still elevated above the expected concentration for water in equilibrium with the atmosphere, this is often attributed to a terrigenic source. We propose that compressed air used during and after well installation is a potential source of excess air, which can sometimes explain elevated SF6 concentrations from wells drilled in the last few decades. This concept is demonstrated by correcting elevated SF6 and CFC‐12 measurements from 55 wells at field sites in the Pilbara region of Western Australia with up to 10 mL(STP)/kg of atmospheric air from the time of drilling (2006–2016). The resulting SF6 and CFC‐12 concentrations are consistent with recharge between 1950 and 1970 for most wells. Excess air in recharge from that period could not have contained enough SF6 to explain the measured concentrations. This decoupling of excess air from recharge is potentially also significant for other gaseous age tracers with limited solubility including SF5CF3, Halon 1301, 39Ar, 85Kr, and 81Kr.

Evaluations of effects of sleep surfaces on athletic performance in youth

We recently demonstrated that sleeping on high rebound [HR] mattress toppers induced a continuous and more rapid decline in core body temperature compared to low rebound [LR] mattress toppers during the initial phase of nocturnal sleep in young healthy volunteers. HR toppers are characterized by their supportive feel and high breathability whereas LR toppers are pressure-absorbing. In the current study, we evaluated effects of HR mattress toppers on objectively-(actigraphy) and subjectively-(questionnaires) evaluated sleep, vigilance (psychomotor vigilance test), and athletic performance (40-m sprint time, long jump distance, and star drill time) in youth male athletes age 10–19, in two sessions: fifty-one subjects in 2013 (study I) and 23 subjects in 2014 (study II). Sleeping on HR mattress toppers for four to six weeks improved some athletic performance measures compared to sleeping on LR or sleeping directly on spring mattresses without a topper. Statistically significant improvements in 40-m sprint time in study I (compared to LR) and in star drill time in study II (no topper) were observed. No changes in sleep and psychomotor vigilance were observed. These results suggest selecting optimal sleep surfaces may contribute to the maximization of athletic performances, and further studies are warranted.

A Novel Method to Reduce the Laser Drilling Time for Hole Cluster considering the Influence of Residual Vibration of the Sample Stage

In large areas of laser drilling, the residual vibration occurs when the sample stage moves in PTP (Point to Point) movement. It affects the surface quality and processing efficiency of the holes. The common solution for this problem is to set the laser irradiation delay time by the controller to wait for the residual vibration attenuation, but the whole drilling circle will increase. In this paper, a new method is introduced to reduce the laser drilling circle. By setting the allowable threshold of the residual vibration for the subsequent process, the sum of the time in deceleration segment of the trapezoidal moving profile, and the time when the residual vibration attenuates below the amplitude threshold (ST) can be minimized as the optimization goal. The results show that for a given operating speed, there is always an optimum acceleration value for the deceleration segment of the trapezoidal moving profile, which minimizes the ST value. Further, the delay time for laser irradiation can also be estimated according to the optimal acceleration during laser drilling.

A Dual-Motor Drill Reduces Plunge, Simultaneously Gauges Depth, and Saves Time When Placing Orthopedic Screws

The technique for placement of orthopedic hardware remains unchanged despite technological advances. The surgeon controls drill bit speed and advancement, which risks drill bit overpenetration, or plunge. Measurement is performed as an additional step, introducing measurement error and increasing operative time. A dual-motor drill was created to control drill variables and combine drilling and measurement into a single step. The purpose of this study was to determine whether a dual-motor drill could reduce drilling and measurement errors while increasing the speed of placement of orthopedic hardware. Five orthopedic surgeons drilled and measured 10 holes with a standard drill and a dual-motor drill in randomized bicortical bone blocks. The bone blocks were placed on standard ballistic gels, which left a defect from drill bit overpenetration that could be measured with a calibrated gauge. The accuracy of drilling was determined by the depth of the defect in the ballistic gel and was compared between groups. Finally, time for drilling and measurement was collected and compared between groups. Overpenetration for the dual-motor drill (0.5±0.3 mm) was significantly less than for the standard drill (8.4±1.9 mm) (P<.0001). Depth measurement error for the dual-motor drill (0.6±0.3 mm) was significantly less than for the standard drill (2.6±0.5 mm) (P<.0001). Drilling and measurement time for the dual-motor drill (6.0±2.2 seconds) was significantly less than for the standard drill (13.4±3.9 seconds) (P<.0001). Use of a dual-motor drill reduced overpenetration, improved measurement accuracy, and reduced time spent during placement of orthopedic hardware. [Orthopedics. 2020;43(5):e465-e470.].

Research on remote intelligent control technology of throttling and back pressure in managed pressure drilling

In order to reduce the non production time of drilling, improve the efficiency and safety of drilling, improve the economic effect of managed pressure drilling (MPD), and realize the intelligent control construction of digital oilfield. Based on the pressure control in MPD, this paper analyzes the pressure control drilling system, takes the wellhead back pressure as the controlled parameter, calculates the mathematical model of the throttle valve according to the characteristics of the throttle valve, the basic parameters and boundary conditions of pressure control drilling, and puts forward an improved particle swarm Optimization PID neural network (IPSO-PIDNN) model. By means of remote communication, VR technology can realize remote control of field control equipment. The real-time control results of IPSO-PIDNN are compared with those of traditional PID neural network (PIDNN) and traditional Particle Swarm Optimization PID neural network (PSO-PIDNN). The results show that IPSO-PIDNN model has good self-learning characteristics, high optimization quality, high control accuracy, no overshoot, fast response and short regulation time. Thus, the advanced automatic control of bottom hole pressure in the process of MPD is realized, which provides technical guarantee for the well control safety of MPD.

Mechanical study on the wellbore stability of horizontal wells in natural gas hydrate reservoirs

Currently, the exploration of natural gas hydrates (NGHs) is regarded as a worldwide research focus. Due to multiple characteristics of NGH reservoirs (such as weak bonding, low strength and high degradability), wellbore instability is extremely likely to occur during drilling operations. Based on the thermodynamic characteristics of NGHs, a heat–fluid–solid coupling numerical model of horizontal wells in NGH reservoirs that considers the decomposition of hydrates was established. Additionally, the evolution of stress fields and plastic zones induced by changes in the temperature–pressure field and the mechanical properties of NGHs before and after their decomposition were analyzed. The results showed that stress was reduced in the zone where NGHs were completely decomposed, due to the weakening of elastic parameters, and that the strata close to the wellbore were in a state of plastic flow because of stress concentration there. Moreover, the stress was dramatically increased in the transition zone for the decomposition of NGHs due to the change in the mechanical properties of the strata. Hence, the secondary stress concentration was formed in the strata where NGHs did not undergo decomposition, and part of this strata would be subjected to plastic deformation. With the further decomposition of NGHS, the extent of the strata with completely decomposed NGHs in the plastic stage was also increased, and the secondary stress concentration effect formed in the zone with NGHs that did not undergo decomposition, in the strata far from the wellbore. If NGHs were decomposed under the selected drilling conditions, the small wellbore was more affected by the decomposition of hydrates, with a greater risk of collapse. Moreover, the effect of the wellbore size became more significant with increased drilling time; thus, selecting a large wellbore for drilling was more favorable for the stability of the wellbore.

Design and field test of drilling composite impactor

When the PDC drill bit encounters the heterogeneous and highly abrasive formation, it comes up with problems such as serious stick-slip phenomenon, shallow depth of penetration and short service life, and meanwhile, the rapid drilling tool with a single impact function cannot meet the drilling acceleration demand of exploration and development in deeper and more complex formation. Therefore, as a complementary implement of the traditional percussion drilling tools, a efficient drilling composite impactor has been designed, which is capable of applying both the reciprocating torsional impact and the reciprocating axial impact. The impact characteristic parameters of the tool have been obtained through the ground performance test, which also verifying the reliability of the composite impact timing, in addition, the field application has been carried out in Tian17-Xie12 well. And the results show that the key drilling parameters, such as well inclination and azimuth, change stably, thus shortening the sliding drilling time, and compared with adjacent wells, the tool above-mentioned has improved the mechanical drilling rate by 38%.

Building 1D Mechanical Earth Model for Zubair Oilfield in Iraq

Many problems were encountered during the drilling operations in Zubair oilfield. Stuckpipe, wellbore instability, breakouts and washouts, which increased the critical limits problems, were observed in many wells in this field, therefore an extra non-productive time added to the total drilling time, which will lead to an extra cost spent. A 1D Mechanical Earth Model (1D MEM) was built to suggest many solutions to such types of problems. An overpressured zone is noticed and an alternative mud weigh window is predicted depending on the results of the 1D MEM. Results of this study are diagnosed and wellbore instability problems are predicted in an efficient way using the 1D MEM. Suitable alternative solutions are presented ahead to the drilling process commences in the future operations.

3-Dimensional Accuracy of Dynamic Navigation Technology in Locating Calcified Canals

IntroductionThis study aimed to present a novel dynamic navigation method to attain minimally invasive access cavity preparations and to evaluate its 3-dimensional (3D) accuracy in locating highly difficult simulated calcified canals among maxillary and mandibular teeth. MethodsThree identical sets of maxillary and mandibular 3D-printed jaw models composed of 84 teeth in their anatomic locations with simulated calcified canals (N = 138 canals) were set up on dental manikins. The Navident dynamic navigation system (ClaroNav, Toronto, Ontario, Canada) was used to plan and execute access preparations randomly with high-speed drills by a board-certified Endodontist. Two-dimensional (2D) and 3D horizontal, vertical, and angulation discrepancies between the planned and placed access preparations were digitally measured using superimposed cone-beam computed tomographic scans. Analysis of covariance models were used to evaluate the associations and the interaction between tooth type and jaw, the canal orifice depth, and the discrepancies between planned and prepared access cavities. The significance level was set at .05. ResultsThe mean 2D horizontal deviation from the canal orifice was 0.9 mm, and it was significantly higher on maxillary compared with mandibular teeth (P < .05). The mean 3D deviation from the canal orifice was 1.3 mm, and it was marginally higher on maxillary teeth in comparison with mandibular teeth (P ≥ .05). The mean 3D angular deviation was 1.7 degrees, and it was significantly higher in molars compared with premolars (P < .05). The 3D and 2D discrepancies were independent of the canal orifice depths (P > .05). The average drilling time was 57.8 seconds with significant dependence on the canal orifice depth, tooth type, and jaw (P < .05). ConclusionsThis study shows the potential of applying dynamic 3D navigation technology with high-speed drills to preserve tooth structure and accurately locate root canals in teeth with pulp canal obliteration.

Production and Environmental Monitoring at PAO Surgutneftegaz

This paper analyzes the performance of systems for removal of sludge from the drilling mud. It shows that the solid-phase particle-size distribution, which depends on the mineral composition and the physico-mechanical properties of rock, the drilling mud process parameters and the type of the rock cutter, as well as the drilling parameters affect the performance of vibrating screens, hydrocyclones, and centrifuges. The paper proposes upgrading the cleaning system by installing a second layer of fine-meshed sieve cassettes where hydrocyclones discharge their output. This improvement reduces the unproductive drilling time.

Optimizing Drill Bits Performance in Highly Unconfined Compressive Strength Formation, Sinai Oil Field, Egypt

In Belayim Oil field, Sidri concession, 8 1/2" section is composed of conglomerates with overall Unconfined Compressive Strength (UCS) varies from 25,000 to 40,000 psi. This section was mainly drilled with Polycrystalline Diamond Compact (PDC) bits and Tungsten Carbide Insert (TCI) drill bits. Drilling 1000 meter in 8 1/2" section needed minimum 6 to 8 drill bits. The average rate of penetration (ROP) was 2.8 (meter per hour) MPH and the average drilled interval was 135 m. The rock bit that had been used in offset wells achieved low ROP and short drilled intervals as well, meanwhile, PDC bit achieved moderate average ROP and relatively short run intervals The operator target was to reduce the drilling time by raising ROP and the drilled interval per drill bit; the hybrid bit was presented to achieve that target. The hybrid bit achieved the highest ROP record and the longest drilled interval in Sidri concession achieving 200 percent improvement from offsets’ average performance. Finally, the paper recommended using three hybrid bit in the first three runs and in the fourth run, where the unconfined compressive strength reached its maximum values, TCI drill bit could be used.

Experimental Study and Investigation of Thrust Force and Delamination Damage of Drilled Ramie Woven Reinforced Composites

One of the machining failures in composite materials is delamination damage. In this paper, machining parameters and delamination damage caused by the drilling process on ramie woven reinforced composite material with an unsaturated polyester matrix were investigated. The ramie woven used is ramie yarn type 12S/3. The machining process used 1.5 kW Pillar drills, where variations in the diameter of the "brad &amp; spur" drill are 4 mm, 6 mm, 8 mm, and 10 mm, respectively. In this work, focuses on the influence of machining parameters like feeds rate and spindle speed. Holes quality was analyzed in terms of thrust force and delamination failure. From the results of this study, the thrust force value obtained at the time of drilling is very closely related to the delamination damage that happens. Delamination damage occurs on both sides of the holes drill.

Investigation on the Continuous Wave Mode and the ms Pulse Mode Fiber Laser Drilling Mechanisms of the Carbon Fiber Reinforced Composite.

The near infrared (NIR) laser drilling of a carbon fiber reinforced polymer (CFRP) composite in the continuous wave (CW) mode and the ms pulse mode was investigated by an experiment and a numerical simulation. The relationships between the laser penetrating time, entrance hole diameter, surface heat affected zone (HAZ) width, and material ablation rate and the laser irradiation time and laser peak power densities were obtained from the experiment. For the same average power density of the laser output, 3.5 kW/cm2, it was found that the ms pulse laser mode, which had a higher peak power density, had a higher drilling efficiency. When drilling the same holes, the pulse laser mode, which had the highest peak power density of 49.8 kW/cm2, had the lowest drilling time of 0.23 s and had the smallest surface HAZ width of 0.54 mm. In addition, it was found that the laser penetrating time decreased sharply when the peak power density was higher than 23.4 kW/cm2. After analyzing the internal gas pressure by the numerical simulation, it was considered that a large internal gas pressure appeared, which resulted from polymer pyrolysis, causing a large amount of the mechanical erosion of the composite material to improve the drilling efficiency. Therefore, the ms pulse laser showed its potential and advantage in laser drilling the CFRP composite.

Guest Editorial: What Do We Want From Our Wells: Drilled Fast or Drilled Right?

Guest editorial I have been proud to be a member of DSATS, SPE’s Drilling Systems Automation Technical Section, for many years, currently serving as a board member. I think DSATS can be rightly proud of what it has achieved, and it is good to see drilling rig automation increasing as the industry realizes its benefits—solving problems including rigsite safety and consistency, and creating opportunities such as more efficient operations and, there-fore, cheaper wells drilled more quickly. We don’t talk so much about downhole automation of the drilling process, specifically directional drilling, even though it too is gradually progressing. What problems might it solve and what opportunities might it create? I am going to argue that the opportunity is huge, if only we look in the right place. The opportunity is not only to reduce the cost of drilling the well but also to increase its value. A recent commentary on lifting costs from US basins published in JPT (August 2019) mentioned multiple ways of reducing drilling time and saving money (including driving down service company pricing, which may well not be a suitable solution) in order to reduce the break-even oil price. But it did not mention the other side of the equation—increasing the value of the well once drilled by maximizing ultimate recovery. How can automation of directional drilling increase the value of the well? In my role with DSATS, and in collaboration with other SPE technical sections, I was fortunate to lead the subcommittee organizing a special session at the 2018 SPE Annual Technical Conference and Exhibition (ATCE). The theme of the session was “The Automation of Well Placement.” We heard from experts on directional drilling and surveying, and to create some tension in the ensuing panel session, we looked for an expert in production. Shauna Noonan, now SPE President, filled that role for us and gave the room valuable insight into some of the damage we can do if we ignore wellbore quality and tortuosity in our quest for speed. Many others have written about the cost of poor well quality: drilling cost in terms of torque and drag, and stuck pipe; potential issues with cementing and running completions; failures of production equipment, including rods and electrical submersible pumps; and production problems such as liquid holdup from vertical undulations in the lateral. According to 2016 data from the US Energy Information Administration, the typical cost of a US onshore well is between $4.9 million and $8.3 million. Based on analysis of operator investor relations presentations, typical ultimate recovery from a Permian Basin well is between 500,000 and 750,000 bbl. If we increase the cost of the well slightly by drilling more carefully and not trying to drill as fast as possible, do we increase its value by a larger amount? Is it a good tradeoff? I am convinced that we do, and that it is—but who knows? I do not believe that we have the numbers, or consensus, to decide.

The Calculating Method of Rock Compressive Strength Based on Logging Data

Rock compressive strength was a basic lithomechanics parameter. And rock compressive strength affected the drillingability and stability of rock in drilling engineering. So a calculating method of stratum rock compressive strength was needed to raise the reliability of stratum information acquired. Then the bit selection, well design and reservoir stimulation design could be more accurate. By analyzing the experiment data of rock 3-axis compressive strength, a logging interpretation method of confining pressure has been established, and by considering the influence of confining pressure, a quantitative calculating method of rock compressive strength based on the logging data has been given. This model was used to analyz an exploration well. The results showed that the rock compressive strength was fit to the drilling time, which indicates that this model may accurately recognize the rock compressive strength in the researched area. The result also showed that confining pressure can strongly influence mechanical properties of formation rocks, so if we analyzed the rock mechanical properties, the confining pressure must be taken into account. Besides the method can calculate rock compressive strength in some old well with regular logging data only.

Influence of drilling fluid temperature on borehole shrinkage during drilling operation in cold regions

Frozen soil is a porous elastic-plastic-viscous material with temperature-sensitive properties. Borehole shrinkage occurs due to the plasticity and creep of frozen soil that ensues during drilling operations in cold regions. Based on the change of mechanical properties of frozen soil during the heat transfer process that occurs between the drilling fluid and the formation, a heat-fluid-solid coupling model is established in this paper to analyze borehole shrinkage behaviors in frozen soil. The results show that during drilling operations, the plastic and creep deformation of frozen soil will result in borehole shrinkage. When the borehole is drilled, a certain amount of plastic deformation will occur due to stress concentration. As drilling operations continue, both plastic and creep deformation gradually accumulate. The borehole shrinkage is dominated by the initial temperature of the formation, and the higher the formation temperature, the greater the shrinkage. At the same formation temperature, the initial borehole shrinkage decreases with increasing temperature of the drilling fluid, and the final shrinkage increases nonlinearly with increasing temperature. The drilling fluid temperature should be close to 0 °C when the formation temperature is high to reduce the drilling time. When the formation temperature is low, cold drilling fluid should be used to maintain borehole stability. This study provides a theoretical basis for the selection of drilling fluid temperatures during drilling operations in cold regions.

Piezoelectric Device versus Conventional Rotary Instruments in Implant Site Preparation (Comparative Clinical Study)

Purpose: This study was designed to evaluate and compare the efficiency of piezoelectric device for implant site preparation clinically and radiographically. Materials and methods: The study included 12 patients divided into two groups. The group A received implants prepared with the conventional drills (CDs), while, group B, the piezoelectric devices (PEDs) were used. The stability of implant was measured, immediately, at 2 months, and 4 months after the implant insertion. Also, the drilling time was recorded. While, the Marginal bone loss (MBL) and Bone mineral density (BMD) were recorded immediately, at 3, and 6 months after implant insertion. Results: Group B had a significant higher ISQ values all over the follow up periods. The drilling time of ISP was significantly higher in group B. Regarding the MBL, there was no a statistical significant difference. The BMD increased significantly in group B immediately, and at 3 month. Conclusion: The osseointegration of implants prepared with PED was significantly greater than that of implants which prepared with the CDs all over the time points, but the PEDs need significantly longer surgical time than the CDs