Advanced Drilling Research Articles

Design and testing of a heat transfer sensor for well exploration tools

The exploration of oil, gas, and geothermal wells is moving towards increasingly harsher downhole environments, requiring more and more advanced drilling and intervention tools. The high downhole temperatures threaten the correct functionality of intervention equipment and of standard downhole electronics, which cannot withstand temperatures above 150 °C for an extended period of time. Thermal management of downhole electronics therefore requires critical and accurate knowledge of the thermal interaction between the downhole tools and the wellbore environment for correct tool design, intervention planning and operation. In this work, we present the design, modelling and testing of a sensor for downhole tools that can determine the heat transfer rate between the tool and the harsh downhole environment. An experimental flow loop was used to simulate the interaction between the sensor and the well fluid, and to calibrate the sensor in the range of heat transfer coefficients 0–1000 W/m2 K. Good agreement between model predictions and experimental results was obtained with average and maximum errors of ∼3% and ∼10%, respectively. A sensitivity of up to 8.7 mV/(W/m2 K) was measured and a response time of about 11 s was obtained over a 25% change in the fluid velocity.

Application of aluminium oxide nanoparticles to enhance rheological and filtration properties of water based muds at HPHT conditions

Drilling fluid is of one of the most important elements of any drilling operation, and through ever advancing technologies for deep water and extended reach drillings, enhancement of drilling fluids properties for such harsh conditions need to be investigated. Currently oil based fluids are used in these types of advanced drilling operations, as their performance at high pressure and high temperature conditions, and deviated wells are superior compared to water based fluids. However, the high costs associated with using them, and environmental concerns of such oil base fluids are drawbacks of them at the moment. In this study, we tried to find a solution for such issues through investigation on the potential application of a new nano-enhanced water base fluid for advanced drilling operations. We analysed the performance of water base drilling fluids that were formulated with two type of nanomaterials (aluminium oxide and silica) at both high and low pressure and temperature conditions (high: up to 120°C and 500 psi, low: 23°C and 14.7psi). The results were compared with a base case drilling fluid with no nanomaterial, and they showed that there is an optimum concentration for aluminium oxide nanoparticles that can be used to improve the rheological and filtration properties of drilling fluids. These results demonstrated that nano-enhanced drilling fluids have an improved thermal stability at heightened temperatures and can withstand the harsh conditions in advanced drilling operations while they impose a lower environmental impact and capital costs.

Application of comprehensive prediction method of water inrush hazards induced by unfavourable geological body in high risk karst tunnel: a case study

ABSTRACTWhile tunnelling in karst terrains, karst fissure water may endanger the safety of tunnel engineering and cause geological disasters such as water inrush. To ensure the safety of tunnel construction, in investigation stage, engineering geological and hydrogeological conditions of Jigongling Tunnel was analysed firstly. In design stage, a reasonable prediction method combining with optimization principle was selected to calculate the water inflow according to the geological and hydrogeological conditions analysed in the investigation stage. Then the advanced geological prediction was divided into different classes based on the water inflow. To make an accurate prediction, tunnel seismic prediction method, transient electromagnetic method, induced polarization method and advanced geological drilling were comprehensively applied in construction stage. This method combined with geology analysis, water inflow calculation and classification of advanced geological prediction is successfully applied in the Jigongling Tunnel of Fanba Expressway, and has provided a reference for the similar engineering constructions.

In‐Depth Ophiolite Research Is Inseparable from the Drilling Engineering

Mankind has lived in the earth for countless years, but until now, people are not really understand the connotation of the Earth. We know that the earth composition including the lithosphere, asthenosphere, mantle, and core. The lithosphere supports all the life on Earth. For a long time, geoscientists trying to use all kind of methods such as geological, geophysical, and geochemical methods to detect and study the earth, but our knowledge about earth are mostly indirect. Through the direct observation to the lithosphere, people can understand and recognize the plate movement of ocean and the mainland, crustal stress, earthquakes, volcanic processes, deep resources, the origins of life, global climate change, and biodiversity. They are all the basis of a series of geoscience problems (Su et al., 2010).For our daily lives, as we all know, against landslides, mudslides and other geological disasters, people's responses can only be monitoring, prevention and countermeasures are needed. One of the most important technical means is the drilling methods. For example, through engineering investigation drilling, people can understand the overall structure of the landslide. Through anchor nails, bolt, cable, curtain grouting, soil modification, anti‐slide bored piles of construction, people can prevent landslides, collapse, and other geological disasters.For geosciences, earth scientists are facing a lot of challenges. Plate tectonic theory is one of the 20th century's major scientific achievements. The continental drift assumptions put forward in the early 20th century, but until 1968, the “Geluoma • Challenger” ocean drilling vessel belong to United States had drilled several hundred holes in the ocean, the theory of seafloor spreading and plate subduction model has been confirmed directly by drilling. However, many problems cannot be explained by “Plate theory “on land. A continental dynamics theory is initiating and developing based on the internal driving force of continent. This heralded a landmark geological revolution is coming soon.At the same time, the 21st century human survival and development resources, the environment and disaster reduction, and other issues need to be addressed urgently. All of this requires us to understand the deep Earth, and the only direct means of direct observation of the Earth's continental crust is “Continental Scientific Drilling”.Geological samples, especially those from deep of the Earth, are the most direct study subjects for geologists. But the only way to access the true samples from deep of the earth is drilling. The most direct evidence always originated from the deep of the earth, such as core, cuttings, fluid samples and other physical samples. This is also true for ophiolite researches.Continental scientific drilling has been demonstrated as an efficient technique for directly obtaining information from the Earth's surface to the deep crust, and is acknowledged as “to build a telescope inserting to the interior of the Earth”, as well as “a key for opening the door of the Earth”. Over the past four decades, continental scientific drilling has achieved great success in enhancing our knowledge of the Earth, and in providing information on mineral resources, large engineering projects and global change. These benefits also relate to ophiolite research.Along with China's Brahmaputra River intermittently distributed ophiolite sets. Its distribution in Tibet is more than 1,000 kilometres long and extends along the Brahmaputra and the Indian Ocean to Myanmar and Pakistan. We have completed a number of coring holes along this ophiolite belt in recent years. The cores were collected from these holes provide geologists with real physical samples coring from the depths of the earth, which have played a significant role in deepening their ophiolite research. And the coring drilling projects along this ophiolite belt will be continue for years, to continue to provide geologists enough ophiolite real samples for their researches.No advanced drilling technology, no enough high quality samples from the deep Earth, the in‐depth ophiolite research will be restricted (Zhang et al., 2013).

A CRITICAL REVIEW OF DRILLING WASTE MANAGEMENT TOWARDS SUSTAINABLE SOLUTIONS

Drilling waste management for oil and gas industry involves collection, transportation, processing, recycling, disposal, and monitoring of waste materials in order to reduce their effects on health and environment. In the Exploration and Production industry, environmental concerns have made effective management of drilling waste at well sites a great priority. Effective waste management is thus a key element in a successful drilling project. The industry therefore relies on effective expertise and newer technologies to maintain a balanced trade-off between healthy business activities and environmental effects. Over several decades, the industry has recorded remarkable progress in reducing the effects of drilling activities on the environment. The progressive development and adoption of sustainable drilling waste management protocols by operating and servicing companies have been partly responsible for this success. However, new challenges are emerging due to advances in drilling techniques such as extended reach wells, deep water drilling, multi-lateral drilling, and high-pressure wells. Recently, advanced drill waste treatment methods such as nanotechnology based approach, supercritical fluid extraction, and microwave treatment process have been explored and tested in the laboratory and on pilot scale to see if they can help overcome these challenges and increasingly stringent regulations. This paper reviews the shortcomings of the conventional approaches, their treatment technologies, advantages, and applications. This article enhances understanding of waste management and its treatment process based on sustainability concept. Researchers can find this review useful as an update on the state of drill waste management in the oil and gas industry. It can also serve as a useful guide to develop new rigorous sustainable models, protocols, and techniques to manage drilling waste using the noble concept.

Use of Life-Cycle Drilling-Simulation System on Challenging HP/HT Drilling Operation

This article, written by Special Publications Editor Adam Wilson, contains highlights of paper SPE 178207, “Use of a Life-Cycle Drilling Simulation System on a Challenging HP/ HT Drilling Operation in the Norwegian Sea,” by Laurie Scott, Wintershall; Just Sverre Wessel, SPE, Maersk Training; and Josef Nabavi and Rolv Rommetveit, SPE, eDrilling Solutions, prepared for the 2016 SPE/IADC Middle East Drilling Technology Conference and Exhibition, Abu Dhabi, 26–28 January. The paper has not been peer reviewed. A life-cycle drilling-simulation system (LCDSS) was used during planning, training, and operation in support of a very challenging high-pressure/ high-temperature (HP/HT) drilling operation in the Norwegian Sea. The LCDSS consists of a total modeling system tailor-made for planning, advanced training, and real-time simulation and decision support. This paper presents the LCDSS and elaborates on the use of it in the preparation and training phase and the operational phase, including forecasting. LCDSS The LCDSS used in this work consists of advanced dynamic drilling models and diagnosis technology merged with 3D visualization into a virtual wellbore. The interactions between the various drilling models are seamless and are used in the whole drilling value chain—from planning through training and, subsequently, real-time operations with forecasting. Work-Process Modifications In order to set up the LCDSS delivery, it became apparent that the existing structure of communication and work processes had to adopt the delivery of this service. Therefore, a thorough evaluation had to be conducted in order to include the service into the operation properly. The main challenge was to ensure that the operator was allowed access to relevant data when needed without interfering with everyday tasks. To achieve this, a strong communication line had to be established, to ensure that the communication worked optimally among rig, operator, and remote center.

Delamination Characterization and Comparative Assessment of Delamination Control Techniques in Abrasive Water Jet Drilling of CFRP

Composite laminates are used in many applications in industries like aerospace and aircraft due to their extremely high strength to weight ratio and corrosion resistance properties. The composite laminates are difficult to machine materials, which results into low drilling efficiency and drilling-induced delamination, thus it is important to develop an innovative advanced drilling process to overcome the difficulties related in the machining of composite materials. This work is focused on comprehensive experimental characterization to understand the effect of cutting parameters on the delamination extent during abrasive water jet drilling of carbon fiber reinforced polymer. Processing parameters, such as standoff distance and water pressure plays dominant role in delamination than abrasive flow rate. It also describes the development of different techniques for controlling the delamination in abrasive water jet drilling process, such as backup plate, pre-drilled hole and water immersion (under water). The analysis shows that abrasive water jet drilling with backup plate yields lower delamination, hole size variation and hole surface roughness.

Environmental Impact of Exploration from Unconventional Gas Deposits in Poland

Abstract Shale formations have been recently treated only as source rocks and sealing packages mainly of conventional deposits. At present shales, which have a considerable concentration of highly mature organic matter appearing in complexes of over 30 m thick are used as unconventional sources for natural gas production with the use of advanced drilling technologies. Natural gas production in such rock formations necessitates performing a horizontal section in the borehole and a big number of hydraulic fracturing jobs. The unconventional shale gas deposits have been prospected also in Poland for a couple of years. Exploration works mainly concentrate on a vast area passing from Pomerania through Mazowsze to the Lublin region in Poland. The analysis of the geologic analyses reveals that the most perspective are shales in the Lower Paleozoic at a depth of 2500 m in the eastern part to about 4000 m in the western part of the area. The paper is focused on the quantitative and qualitative evaluation of environmental impact of natural gas exploration works from unconventional deposits. Special attention was paid to the hydraulic fracturing jobs in shales, which create particular hazard for water and soil environment. These hazards already appear at the stage of preliminary works, when big quantities of chemicals and water for frac jobs are stored in the rig area, and then, during realization of works, when the spent hydraulic fracturing fluid may penetrate the water-bearing horizons in the caprock. The composition of fracturing fluid used in Gapowo B-1A well are given along with the results of chemical analyses of a few parts of spent fracturing fluid samples pumped out from the borehole. The fluid turned out to be high in salt (high specific electrolyte conductance (SEC) and total dissolved substances (TDS) and a high toxicity for most of the living organisms). For this reason the spent fracturing fluid should not enter the environment without control.

Technology Focus: Reservoir Performance and Monitoring (September 2015)

Technology Focus Recent months have been very challenging for the oil and gas industry. When the previous Reservoir Performance and Monitoring feature appeared in JPT in September 2014, Brent was trading at approximately USD 105/bbl. At the end of June 2015, when this statement was written, its price was 41% lower, at just above USD 62/bbl. In addition, the world rig counts reported by Baker Hughes in September 2014 and June 2015 were 3,659 and 2,152, respectively, a decrease of approximately 41% (rig count is a trailing indicator of oil price). The international and North America rigcount decreases between September 2014 and June 2015 were approximately 12 and 57%, respectively. These steep decreases, mostly the direct consequence of a global imbalance between demand and supply, are warnings that our conventional innovation schemes need to be recalibrated. Even if the rig count has been dropping, the rig efficiency continues to improve. From multiwell pads to advanced drilling technologies, innovation is helping keep current production high. If current low prices persist, further innovation may improve the alignment between short-term production and long-term recovery, while lowering overall production costs. Maximizing short-term production and optimizing longterm recovery may provide key opportunities for cost savings during the next downturn of major proportions. This could be achieved through the industry’s ability to innovatively acquire and interpret data for optimizing the reservoir performance. The industry is continuously looking at new monitoring devices and techniques, and there are huge opportunities for monitoring fieldwide data with the ultimate goal of understanding the reservoir better and predicting its short- and long-term production more accurately. The current downturn may be a great opportunity for the big-data revolution from other industries to be extended to the oil and gas industry in general and to reservoir performance in particular. As a result of the industry’s current efforts to improve reservoir performance and reduce production costs, many great papers have been presented at recent SPE conferences and meetings. From the more than 100 papers reviewed for this feature, approximately half of them present case histories, field-data interpretation, and work flows, and the other half present theoretical and laboratory results. The papers summarized in this feature and recommended as additional reading are excellent samples of this distribution. JPT Recommended additional reading at OnePetro: www.onepetro.org. SPE 170619 Wireless Inflow Monitoring in a Subsea Field Development: A Case Study From the Hyme Field, Offshore Mid-Norway by Svein Mjaaland, Statoil, et al. IPTC 18115 Three-Dimensional Visualization of Solvent Chamber Growth in Solvent-Injection Processes: An Experimental Approach by F. Fang, University of Alberta, et al. SPE 171932 Linking Diagenesis, NMR, and Dynamic Data for Accurate Flow Characterization of Heterogeneous Carbonate Reservoir by Umer Farooq, Abu Dhabi Company for Onshore Oil Operations, et al. SPE 172929 Production Forecast, Analysis, and Simulation of Eagle Ford Shale Oil Wells by Basel Alotaibi, Texas A&M University, et al.

An Integrated Approach for Drilling Optimization Using Advanced Drilling Optimizer

The ability to optimize drilling procedures and economics involves simulation to understand the effects operational parameters and equipment design have on the ROP. An analysis applying drilling performance modeling to optimize drilling operations has been conducted to address this issue. This study shows how optimum operational parameters and equipment can be predicted by simulating drilling operations of preexisting wells in a Northwest Louisiana field. Reference well data was gathered and processed to predict the “drillability” of the formations encountered by inverting bit specific ROP models to solve for rock strength. The output data generated for the reference well was formatted to simulate upcoming wells. A comparative analysis was conducted between the predicted results and the actual results to show the accuracy of the simulation. A significant higher accuracy is shown between the simulated and actual drilling results. Once simulations were validated, optimum drilling parameters and equipment specifications were found by varying different combinations of weight on bit (WOB), rotary speed (RPM), hydraulics, and bit specifications until the highest drilling rate is achieved for each well. A qualitative and quantitative analysis of the optimized results was conducted to assess the potential operational and economic benefits on drilling operations.

Automated Dual Gradient Drilling and its Parametric Analysis during Connection

Since Dual Gradient Drilling (DGD) is a new and advanced drilling technology, currently its methods, procedures, simulations and experiments are still underdeveloped. It requires more study, research and advanced methods on DGD systems. The motivation of the paper is to study DGD systems, design good operational drilling parameters, and work on automated DGD systems to further realize safe and efficient drilling. This paper aims to implement automated DGD systems by regulating the mud level in the riser to maintain the stable bottom hole pressure during connection operations. Furthermore, the sensitivity analysis of parameters is included and good configuration parameters are recommended.

CO2 Utilization and Storage in Shale Gas Reservoirs: Experimental Results and Economic Impacts

Natural gas is considered a cleaner and lower-emission fuel than coal, and its high abundance from advanced drilling techniques has positioned natural gas as a major alternative energy source for the U.S. However, each ton of CO2 emitted from any type of fossil fuel combustion will continue to increase global atmospheric concentrations. One unique approach to reducing anthropogenic CO2 emissions involves coupling CO2 based enhanced gas recovery (EGR) operations in depleted shale gas reservoirs with long-term CO2 storage operations. In this paper, we report unique findings about the interactions between important shale minerals and sorbing gases (CH4 and CO2) and associated economic consequences. Where enhanced condensation of CO2 followed by desorption on clay surface is observed under supercritical conditions, a linear sorption profile emerges for CH4. Volumetric changes to montmorillonites occur during exposure to CO2. Theory-based simulations identify interactions with interlayer cations as energetically favorable for CO2 intercalation. In contrast, experimental evidence suggests CH4 does not occupy the interlayer and has only the propensity for surface adsorption. Mixed CH4:CO2 gas systems, where CH4 concentrations prevail, indicate preferential CO2 sorption as determined by in situ infrared spectroscopy and X-ray diffraction techniques. Collectively, these laboratory studies combined with a cost-based economic analysis provide a basis for identifying favorable CO2-EOR opportunities in previously fractured shale gas reservoirs approaching final stages of primary gas production. Moreover, utilization of site-specific laboratory measurements in reservoir simulators provides insight into optimum injection strategies for maximizing CH4/CO2 exchange rates to obtain peak natural gas production.

Intelligent-Well Completion in the Troll Field Enables Feed-Through Zonal Isolation

This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper SPE 160060, ’First Intelligent-Well Completion in the Troll Field Enables Feed- Through Zonal Isolation: A Case History,’ by Bjorn Olav Dahle, Statoil, and Peter E. Smith, Geir Gjelstad, and Kristian Solhaug, Halliburton, prepared for the 2012 SPE Annual Technical Conference and Exhibition, San Antonio, Texas, USA, 8-10 October. The paper has not been peer reviewed. Statoil, operating the Troll field in the Norwegian sector of the North Sea, wished to run a deep sidetrack from the main bore in a multilateral well that would exit through the liner in the reservoir. Several zonal-isolation methods had been evaluated, but on the basis of previous experience Statoil decided to use swellable-packer technology. Testing revealed that this type of completion would exceed the necessary requirements. The installation was performed from a semisubmersible rig ahead of plan. Introduction The Troll field lies approximately 65 km west of Kollsnes, near Bergen, Norway. Although the field historically has produced large amounts of oil, it is now primarily a gas producer and contains approximately 40% of the total gas reserves on the Norwegian continental shelf. The gas reservoirs, which are 1400 m below sea level, are expected to produce for at least another 70 years. The massive Troll A platform produces gas, while Troll B, a floating process and accommodation platform with a concrete hull, and Troll C, a floating process and accommodation platform with a steel hull, produce from thin oil-bearing layers in the Troll West reservoir. The thin oil layer is between 22 and 26 m thick in the Troll West oil province and is between 11 and 13 m thick in the Troll West gas province. In order to recover oil from the thin layer, it has been necessary to develop advanced drilling and production technology. All of the more than 110 production wells to be drilled are horizontal wells. This process requires two-phase drilling. The first phase drills down to the reservoir, 1600 m beneath the sea bottom, and then the second phase drills to 3200 m in a horizontal direction through the reservoir. Twenty-eight of the wells are multilaterals that have two or three horizontal laterals. The well in question faced several challenges normally not seen in Troll multilateral completions, including standalone-screen completion with zonal isolation, well paths with doglegs and a completion total depth (TD) of more than 6000 m, top completion with zonal isolation and zonal control for four zones, and the need for dual pressure and temperature monitoring for all oil zones.

Shale 2.0: From Efficient to Effective Shale Development

Guest editorial Hydrocarbons from shale were first produced commercially as long ago as 1821, and from the 1860s through the 1920s gas was produced from shallow, low-pressure, naturally fractured shales in the eastern US. However, today’s shale “revolution” did not really begin until 1985. That was when George Mitchell started developing a model for economically viable exploitation of the Barnett Shale. It took almost 20 years and literally hundreds of wells to find the right formula, based on two transformative technologies: horizontal drilling and multistage hydraulic fracturing. Shale 1.0: The Quest for Operational Efficiency Since roughly 2005—the beginning of what I call Shale 1.0—we have successfully revived old shale plays and developed new ones. Every year, North American companies complete thousands of wells in shale reservoirs. However, even in mature plays like the Barnett, where productivity per well has doubled or tripled over the past decade, as many as 30% of all perforation clusters contribute absolutely nothing to production. That is the same as drilling 30 totally nonproductive wells out of every 100. To improve shale economics, operators and oilfield service companies have focused considerable brainpower and technical resources on reducing the unit cost of production through greater operational efficiency. In many cases, we have brought drilling and completion costs down 50%, largely through application of new technologies, efficient project management, and supply chain negotiations. In some cases, advanced drilling technologies, automation, and real-time data have slashed average time to total depth from 48 days to just 8. Not all new technologies are exotic. For example, installation of rupture disk valves—which replace coiled tubing or drillpipe-conveyed perforations for the first stage in horizontal wells—reduced completion costs in 15 Eagle Ford wells by more than USD 100,000 per well. The shale revolution has yielded many economic and social benefits, including growth in jobs and local businesses across the US, lower domestic energy costs, reduced CO2 emissions, and—perhaps most important—access to a new national resource that holds enormous potential for long-term energy security. According to the Institute for Energy Research, the US has more than 200 years’ capacity of technically recoverable oil reserves and 110 years’ worth of natural gas at current rates of consumption, much of those from unconventional plays. In fact, shale oil is leading the current growth in US crude production. The US Energy Information Administration conservatively predicts global shale oil production will reach more than 4 million BOPD by 2030. Other analysts double that estimate.

Experimental Analysis of a Novel Rotary Ultrasonic Assisted Drilling (RUAD) Machine

Ultrasonic assisted drilling (UAD) is an advanced technology, with proved benefits on drilling quality and productivity, in particular for the materials with low machining properties, such as super alloys. However, it suffers from the limitations incurred by the rotation incapability of the vibrating tool. In this research, this major drawback is overcome by improving the system thorough providing rotational capability to the vibrating tool. Consequently, this advanced drilling technology can be used for any industrial part, regardless of its size and the location of the hole. An innovative mechanism is designed, which utilizes an ultrasonic transducer to axially vibrate the drilling tool, while it is simultaneously rotating. It is actually a portable tool holder interface, which can easily be installed in different machines. Unlike prior work, the brush mechanism is readily accessible for required repair and maintenance. Once the setup is prepared, a set of accurately designed experiments and associated statistical studies are carried out using factorial design of experiment (DOE). Spindle speed, feed rate, and the vibration amplitude are taken as input factors, while surface roughness, circularity, and cylindricity are studied as output parameters. The obtained results are quite encouraging, showing that all the benefits of UAD are achieved in the new system, while its major limitation is overcome.

Effect of Sour Environments On Corrosion Fatigue Crack Propagation in Advanced Drilling Steel

not Available.

Advanced Drilling Simulation Environment for Testing New Drilling Automation Techniques and Practices

Summary Newly developed drilling automation systems locate a computer interface between commands issued by the driller and instructions transmitted to the drilling machinery. Such functions are capable of faster and more precise control than can be achieved by an unaided operator and thus can help drilling within narrow margins. To ensure that these systems work properly in all circumstances, an advanced drilling simulator has been developed to enable testing under a wide range of simulated conditions. The environment described in this paper uses hardware in the loop (HIL) simulation to verify that the automation techniques being tested respond correctly in real time. Rigorously validated physical models of the drilling process simulate the response of the well to the commands given to the drilling machines. Abnormal drilling conditions (e.g., packoffs, kicks) and equipment or machine-related problems (e.g., plugged nozzles, power shortage) are convincingly recreated. The drilling simulator models the behavior of surface equipment such as the activation of gate valves to line up different pits or the flow in the mud return. It simulates changes in the drilling fluid properties when mixing additives to the mud. It is therefore possible to focus training sessions on cooperation between different groups at the wellsite. This is particularly useful when planning the introduction of drilling automation that involves new work procedures as a result of automation and adaptation of the drilling team to a new operational environment. Drilling operations are becoming more and more complex. Automation has the potential to provide large improvements in efficiency and safety, but automation technologies must be implemented correctly at the workplace. Just as the aviation industry has used simulated environments for decades, drilling simulation environments are the key to the safe and successful implementation of drilling automation and the development of crew skills to face future challenges.

Technology Focus: Horizontal and Complex Trajectory Wells (November 2012)

Technology Focus Although horizontal wells were used sporadically in Europe and elsewhere for many years, the technique was not widely employed in oil and gas developments until the Austin chalk oil boom in Texas from the late 1980s to the mid-1990s. As the Austin chalk activity subsided, so did application of horizontal wells in the US. However, the industry took the lessons learned and applied them to an increasingly wide range of reservoirs around the world. This approach delivered massive economic and environmental benefits that expanded as experience grew. The ensuing confidence in horizontal wells attracted investment in technologies targeted at pushing boundaries, increasing value, lowering cost, and predicting horizontal-well effect on reservoir performance. In many locations, field development strategies were totally transformed. Simultaneously, development of unconventional reservoirs was being incentivized in the US. These financial incentives initially encouraged the development of tight gas, frequently using horizontal wells. By 2006, the lessons learned and technologies developed in US tight gas were being combined with those developed for horizontal wells in more conventional reservoirs around the world. Successes led to the US shale gas boom. This provided a climate conducive to investment in technology aimed at further lowering cost and increasing performance of horizontal wells in shale to drive viability. These collective lessons and technologies will be instrumental in unlocking the potential of unconventional reservoirs around the world. However, this knowledge transfer will not be easy. Learning curves on the application in new areas should be expected before success can be claimed. Two challenges will be to steepen the learning curves and to gain acceptance. Success will require technical and economic derisking of developments at every stage, along with assured high degrees of technical integrity, efficiency, and predictable performance. Paramount to achieving this is development of people with the right technical skills, coupled with the ability to capture and trans-fer lessons learned across boundaries. New technology advancements will follow as these people identify future requirements. This overview indicates how far horizontal wells have progressed over 25 years and how critical they remain in maintaining an affordable global energy supply into the future. It also serves as an illustration of the international nature of our industry and gives some insight into what it takes to stimulate advancement. The papers reproduced here show how horizontal wells enable development of an ever-wider range of reservoir types around the world and how improved modeling, planning processes, and monitoring help reduce the associated risks. Recommended additional reading at OnePetro: www.onepetro.org. SPE 142439 Shallowest Horizontal Well Drilled in the Middle East: Challenges and Successes by Abhijit Dutta, KOC, et al. (See JPT, November 2011, Page 88.) SPE 151466 Using Advanced Drilling Technology To Enable Well Factory Concept in the Marcellus Shale by Olof Hummes, Baker Hughes, et al. SPE 146104 Strategies To Minimize Frac Spacing and Stimulate Natural Fractures in Horizontal Completions by Nicolas P. Roussel, The University of Texas at Austin, et al. SPE 143071 Effective Well Placement and Trajectory Planning Approach Through Collaboration Environment Tools by Ahmed M. Al-Baqawi, Saudi Aramco, et al.

Application of Novel Technologies Helps Unlock Deep Omani Gas

This article, written by Editorial Manager Adam Wilson, contains highlights of paper SPE 152436, ’Application of Novel Technologies Helps Unlock Deep Omani Gas,’ by Andreas Briner, SPE, Joe Curtino, and Hisham Al-Siyabi, Petroleum Development Oman, and Tobias Judd, SPE, Schlumberger, prepared for the 2012 SPE Middle East Unconventional Gas Conference and Exhibition, Abu Dhabi, 23-25 January. The paper has not been peer reviewed. With unique geomechanical, reservoir, and geological properties, some of the large gas-bearing prospects within the Fahud basin in the Sultanate of Oman require innovative drilling and completion practices. A revised drilling and completion workflow, with specific technology deployment and operational flexibility, has been developed in order to account for such reservoir complexity. Introduction Early Paleozoic nonassociated-gas fields operated by Petroleum Development Oman in Oman have traditionally comprised good-reservoir-quality sand-stones located on three- or four-way dip-closed structural highs. While gas-exploration success has continued since 2005, discoveries have been restricted to much poorer reservoirs. Successful continued exploration, appraisal, and further maturation, especially as exploration is also extended into basin-center locations, pose significant challenges given the depth (high temperature and high potential reservoir pressures) and reservoir quality [porosities ranging from less than 3% to 10%, with (ambient) permeabilities ranging from 0.001 to 1 md]. Following a successful completion of a regional basin-evolution and burial history study, a well campaign mainly targeting the Amin-Nimr section in the Fahud Salt basin was designed. The target reservoirs of the Amin formation and Nimr group are Cambro-Ordovician in age and are separated by the Angudan unconformity, estimated to represent a hiatus of up to 20 million years. The Amin and Nimr units are both recognized in the sedimentary basins of north and south Oman, but they have widely differing properties. The Amin formation is a high-net-to-gross-ratio, continental succession deposited in alluvial-/fluvial-fan, sabkha (wet and dry), aeolian, and fluvial sheetflood/sand flat environments, generally with a high water table. The underlying Nimr group comprises two formations, a unit comprising fluvial and lacustrine/playa deposits overlain by a unit comprising large-scale coarsening-upward fluvial deposits. New Operating Model Past reservoir-characterization methods are no longer sufficient when appraising low-permeability gas reservoirs where performance is directly linked to reservoir quality and the effectiveness of the selected method of reservoir stimulation. Several technologies have been applied recently in Oman to improve the understanding of tight gas opportunities, and these include the incorporation of advanced drilling practices; improved understanding of subsurface environment and hydraulic-fracturing design and methodology; hydraulic-fracturing evaluation; and well-completion considerations from a hydraulic-fracturing and subsequent-well-production standpoint.

Research on Advanced Geological Prediction in Highway Double-Arch Tunnel Construction

In this paper, a comprehensive advanced geological prediction method in highway double-arch tunnel construction was put forward, which could take the advantages of geological radar technology and the horizontal of advanced drilling in karst area. The method would give relatively accurate judgments in the construction of the highway double-arch tunnel by using different geological radar survey line layout, combining with advanced horizontal hole, which ensure the construction safety of the tunnel. The practical application of comprehensive advanced geological prediction in double-arch highway tunnel in karst area had received a good effect, and it showed the method had a certain guiding function.