Horizontal Drilling Technology Research Articles

Methodology for reducing energy and resource costs in construction of trenchless crossover of pipelines

The paper suggests a set of measures to select the equipment and its components in order to reduce energy costs in the process of pulling the pipeline into the well in the constructing the trenchless pipeline crossings of various materials using horizontal directional drilling technology. A methodology for reducing energy costs has been developed by regulating the operation modes of equipment during the process of pulling the working pipeline into a drilled and pre-expanded well. Since the power of the drilling rig is the most important criterion in the selection of equipment for the construction of a trenchless crossover, an algorithm is proposed for calculating the required capacity of the rig when operating in different modes in the process of pulling the pipeline into the well.

Microseismicity-derived fracture network characterization of unconventional reservoirs by topology

The advent of horizontal drilling technology, combined with multistaged hydraulic fracturing to create a complex fracture network within the relatively impermeable rock mass, has made natural gas production from tight reservoirs economically feasible. Understanding of the generated fracture network properties, such as its spatial distribution, extension, connection, and ability to percolate, plays a significant role in evaluation of the stimulation efficiency, optimizing analytical frac models, and ultimately enhancing completion programs. We have developed a unique approach to understand the influence of fractures on fluid flow and production from impermeable reservoirs and evaluate completion effectiveness. We characterize the microseismicity-derived discrete fracture network in a North American shale-gas reservoir using modified scanline and topology methods. Using concepts of node and branch classification and assessing the number of connections (fracture intersections), the network connectivity is established volumetrically. The zones of permeability enhancement are then identified using the connection per branch and line ([Formula: see text] and [Formula: see text]), tied to percolation thresholds of the fracture system. These zones consist of a primary zone with a high proportion of doubly connected fractures, a secondary zone populated with partially connected fractures, and a tertiary or unstimulated zone dominated by isolated fractures. These divisions are reflected in the deformation that is observed in the reservoir as measured through a cluster-based description of the microseismicity. The primary and secondary zones are considered spanning fracture clusters, and they take part in production, whereas the tertiary zone is recognized as nonspanning fractures, and though it may enhance the bulk permeability of the rock mass, it is unlikely to contribute to reservoir production.

Effects of nano-pore wall confinements on rarefied gas dynamics in organic rich shale reservoirs

The advancements in horizontal well drilling and multistage hydraulic fracturing technology enabled us to unfold major sources of hydrocarbon trapped in ultra-tight formations such as organic rich shales. Tremendous gas production from these reservoirs has transformed today’s energy landscape [1]. Even though multi-stage hydraulic fracturing stimulation provides high permeability paths to transfer gas to the wellbore, however, most of the gas is stored in nano-organic pores of the ultra-low permeability shale matrix that needs to be transferred to the hydraulic fractures to be able to be produced. Studies using advanced imaging technologies such as FIB/SEM and low temperature adsorption measurements show that in the organic rich shale gas reservoirs, Kerogen, the finely dispersed organic nano-porous material with an average pore size of less than 10 nm holds bulk of the total gas in place (GIP). The molecular level interactions between fluid–fluid and fluid–solid organic pore walls govern the transport and storage in these organic nano-pores.To understand the high gas production rates from these ultra-tight formations, the objective of this study is to advance our understanding of non-ideal gas dynamics in multiscale pore structure of organic rich shale matrix (i.e., gas storage and transport influenced by adsorption and adsorbed gas transport) and develop a model to quantify these effects under wide range of reservoir conditions. Among different methods used to model gas dynamics in organic nano-pores such as the multi-continuum, molecular dynamics and Monte Carlo, the lattice Boltzmann method (LBM) is more effective method with much less computational cost relative to other techniques. In this study we focus on rarefied gas dynamics in Kerogen organic nano-tubes under wide range of reservoir pressure and temperature conditions using a two dimensional LBM model.In this model the Langmuir-slip boundary condition at capillary walls, convection or darcy flow and diffusive transport (slippage of free gas molecules and surface transport of adsorbed molecules combined) are considered to model gas transport. Different transport mechanisms and their contribution in gas transport is investigated in a large range of Knudsen numbers from continuum flow to transition flow regime under different reservoir conditions. The deviation from classical theory of fluid flow in micro channels such as Knudsen’s minimum in the mass flow rate is investigated and the effect of gas slippage and double slippage on Knudsen minimum is discussed in details. Finally the results are compared with analytical, and semi analytical solutions available in the literature.The LBM model results displays a clear indication that the gas transport in the capillary tube is highly depends on the pore width size, pressure and temperature. The relative impact of pore size, pressure and temperature on maximum gas velocity and gas wall velocity differs at different flow regime conditions. A critical Knudsen number exists at different reservoir conditions, where the anticipated parabolic fluid velocity profile in organic nano-pores alters and shows higher flow rate as capillary widths reduces due to the underlying effect of molecular phenomena of double slippage and the wall confinement. The comparison with traditional continuum Hagen-Poiseuille law, Klinkenberg slip theory, and recent modified versions of Klinkenberg slip flow equations show that the previous models are valid only in the continuum flow regime, however, they fail to capture high gas flow rates at high Knudsen number and transition flow regimes which is the case in most of the shale organic nano-pore conditions [2].This work is not only important for the advancement of shale gas flow simulators, but also for organic rich shale characterization.

Cuttings transport in maxi HDD boreholes with front reaming and one way drilling mud return technologies

Cuttings transport becomes critical important when horizontal directional drilling (HDD) technology has been used more often in long distance and large diameter oil and gas pipeline construction in rocks. Front reaming (FR) and one way drilling mud return (OWDMR) were not new in oil and gas well drilling, but they were rarely used in HDD industry compared to the traditional back reaming (BR) and two way drilling mud return (TWDMR). FR and OWDMR technologies, when they were used in HDD, were designed mainly for highly non-leveled HDD projects to overcome some difficulties such as the recycling of drilling mud. Along with these technologies is that the cuttings need to travel longer distance to the ground surface. In addition, the effect of the drill rod rotation on the cuttings transport does not exist because hole bottom mud motor is usually used in FR. To find a solution for this problem, the cuttings transport mechanism was analyzed based on the drilling mud hydraulics, and then, an equation of cuttings transport distance was derived. It found that the average drilling mud velocity in the annulus and the consistency index of drilling mud are the two most important factors related to the cuttings transport distance. To help with the cuttings transport, a new MMH drilling mud system, which provides a high consistency index and a low flow index, was used in rock HDD projects, instead of the common Bentonite-water drilling mud system.

The new method on gas-water two phase steady-state productivity of fractured horizontal well in tight gas reservoir

Based on a large number of tight gas exploration and development literature researches, it is found that the horizontal drilling technology and fracturing operation are usually used in the tight gas reservoir for its low permeability. Three tasks have been done in this paper. First, we described the characteristics and the flow mechanism of the tight gas reservoirs which are different from the conventional ones and gave a new definition of two phase pseudo pressure. Second, formation stress sensitivity, starting pressure gradient and the interaction of fractures are considered. Equivalent flow resistance was used to establish a model of tight gas steady flow, and a new productivity formula of fractured horizontal well in tight gas reservoir derived by the new flow model. Third, the productivity influence research has been done, which gives the influence degree of different parameters. It is signified that the productivity will increase with the addition of the permeability modulus and decrease with the increase of the water-gas volume ratio. The influence of starting pressure gradient was not very clear and the fractures parameters showed the opposite situation. Therefore optimization design of tight gas reservoir development mode can be improved by the productivity formula and research. Cited as : Li, X., Liang, J., Xu, W., et al. The new method on gas-water two phase steady-state productivity of fractured horizontal well in tight gas reservoir. Advances in Geo-Energy Research, 2017, 1(2): 105-111, doi: 10.26804/ager.2017.02.06

Assessing Methane in Shallow Groundwater in Unconventional Oil and Gas Play Areas, Eastern Kentucky.

The expanding use of horizontal drilling and hydraulic fracturing technology to produce oil and gas from tight rock formations has increased public concern about potential impacts on the environment, especially on shallow drinking water aquifers. In eastern Kentucky, horizontal drilling and hydraulic fracturing have been used to develop the Berea Sandstone and the Rogersville Shale. To assess baseline groundwater chemistry and evaluate methane detected in groundwater overlying the Berea and Rogersville plays, we sampled 51 water wells and analyzed the samples for concentrations of major cations and anions, metals, dissolved methane, and other light hydrocarbon gases. In addition, the stable carbon and hydrogen isotopic composition of methane (δ13 C-CH4 and δ2 H-CH4 ) was analyzed for samples with methane concentration exceeding 1 mg/L. Our study indicates that methane is a relatively common constituent in shallow groundwater in eastern Kentucky, where methane was detected in 78% of the sampled wells (40 of 51 wells) with 51% of wells (26 of 51 wells) exhibiting methane concentrations above 1 mg/L. The δ13 C-CH4 and δ2 H-CH4 ranged from -84.0‰ to -58.3‰ and from -246.5‰ to -146.0‰, respectively. Isotopic analysis indicated that dissolved methane was primarily microbial in origin formed through CO2 reduction pathway. Results from this study provide a first assessment of methane in the shallow aquifers in the Berea and Rogersville play areas and can be used as a reference to evaluate potential impacts of future horizontal drilling and hydraulic fracturing activities on groundwater quality in the region.

Fracking and public health: Evidence from gonorrheaincidence in the Marcellus Shale region.

The United States (US) began to experience a boom in natural gas production in the 2000s due to the advent of hydraulic fracturing (fracking) and horizontal drilling technology. While the natural gas boom affected many people through lower energy prices, the strongest effects were concentrated in smaller communities where the fracking occurred. We analyze one potential cost to communities where fracking takes place: an increase of sexually transmitted diseases. We use a quasi-natural experiment within the Marcellus shale region plus panel data estimation techniques to quantify the impact of fracking activity on local gonorrhea incidences. We found fracking activity to be associated with an increase in gonorrhea. Our findings may be useful to public health officials. To make informed decisions about resource extraction, policy makers as well as regulators and communities need to be informed of all the benefits as well as the costs.

Effectiveness of miscible and immiscible gas flooding in recovering tight oil from Bakken reservoirs in Saskatchewan, Canada

Oil production from unconventional tight Bakken reservoirs in North America has been booming since the early 2000s because of the widespread application of horizontal well drilling and multi-stage hydraulic fracturing technologies. Tight oil recovery is made difficult by the extremely low permeability and porosity of the oil-hosting rocks. Two key characteristics in tight oil production are the steep decline in oil production rate and the low ultimate oil recovery. Therefore, maintaining oil production and improving a field project’s economic benefits become urgent issues for the development of tight oil resources. The substantial amounts of residual oil left behind in tight reservoirs demand a viable and effective enhanced oil recovery (EOR) technology after the primary recovery process. This research investigated the effectiveness of miscible or immiscible gas flooding processes using four possible injection gas candidates (i.e., CO2, CO2-enriched flue gas, oilfield-produced gas, and nitrogen) for Bakken tight oil reservoirs in southeast Saskatchewan, Canada. The phase behaviour of the reconstituted live oil–injection gas systems was studied through pressure/volume/temperature (PVT) tests in which important recovery mechanisms of gas flooding, i.e., viscosity reduction and oil swelling effects, were revealed. The minimum miscibility pressures (MMP) for the live oil–injected gas systems were determined using the rising bubble method. The experimental results demonstrated that CO2 had the lowest MMP and largest viscosity reduction and oil swelling among all the tested gases. Therefore, CO2 flooding is considered technically feasible as a miscible process at the current reservoir conditions, while the use of the other three gases would result in an immiscible process. Finally, four coreflood tests using reservoir cores from the Viewfield Bakken field were conducted to evaluate the displacement efficiency. Each coreflood comprised four stages (pressure depletion, initial waterflood, gas injection, and extended waterflood) to represent the actual field production practice. Oil recovery performance confirmed that CO2 miscible flooding was significantly more effective than immiscible flooding with the other injection gases.

Injectable Contrast Agents for Enhanced Subsurface Mapping and Monitoring

Injection of fluids into geologic formations for long term disposition (CO2) or to improve energy extraction operations can benefit from subsurface monitoring programs capable of providing three dimensional spatial imaging of fluid distributions in the host reservoirs. More importantly, advancements in horizontal drilling and fluid fracking technologies are attracting a broader portfolio of non-traditional engineered subsurface reservoirs that possess complex fluid flow typically through engineered fracture networks. For example, producing fossil fuels from tight sands or shale formations, geothermal based heat extraction operations in low-permeability rock formations, and storing injected fluids (i.e. CO2, acid gases, waste waters, etc.) in the subsurface all require rigorous tracking techniques capable of identifying fluid migration. Current methodologies for four dimensional (3D spatial changes over time) subsurface monitoring of injected fluids are typically geophysical, using surface stations and borehole devices which employ seismic, electromagnetic, and gravitational techniques. However current methods often lack sufficient measurement sensitivity to adequately track fluid migration, and often incur a large economic cost. In this paper, we describe an entirely new class of acoustically responsive contrast agents to enable high-sensitivity, high-resolution tracking of injected fluids via conventional seismic imaging that have the potential of improving subsurface fracture network mapping and plume monitoring in CO2 storage operations.

What motivates merger and acquisition activities in the upstream oil & gas sectors in the U.S.?

The U.S. oil and gas (O&G) industry has experienced a tremendous amount of growth in the last decade or so due to the development of horizontal drilling and fracking technology. In the meantime, the industry has experienced heavy merger and acquisition (M&A) activity, especially in the upstream sectors. While these M&A activities may be related to the aggregate M&A waves in the country, they are unique in their own respect. We recognize that the M&A activities in the energy industry in general, and the O&G sectors in particular, can be different from the traditional sense of M&A activities. In this paper, we provide some stylized facts on the M&A patterns in the upstream O&G sectors, focusing on the factors that influenced these patterns. Our empirical evidence suggests that among the variables we studied, oil price and O&G production are the most important factors that influence M&A activities, while other variables do not show consistent effect across regions and definitions of M&A. In addition, the M&A activities had momentum-building periods and had patterns consistent with a wave hypothesis. Our findings support the notion that industry-specific factors are more important than general economic conditions in determining M&A in the O&G industry. We find evidence supporting both the behavioral and neoclassical theories on M&A.

Safety and Fast Horizontal Drilling Technology in Xujiahe Formation of Western Sichuan Basin

Xu-2 formation in Xinchang structure of Western Sichuan Basin is a dense fractured reservoir which is buried deeply. Horizontal well drilling technology can effectively develop such gas reservoir. In this paper, first horizontal well of Xinchang Structure ­­Xin10-1H well was taken as an example, the difficulties encountered in its safety and fast drilling were analyzed and corresponding technical measures were proposed. This summary is helpful to promote the technology of safe and fast horizontal drilling in Western Sichuan Basin.

The Application of Numerical Analysis in Determining the State of the Rock Mass Around Directional Wells

Drilling directional and horizontal wellbores plays an important role in the exploitation of hydrocarbons. In the case of long operated and unconventional fields the importance of this type of drilling is fundamental. The horizontal and directional drilling technologies are also applicable in other fields. Directional and horizontal holes are among other various types of drilling under buildings, microtunnels, injection and storage holes. This technology is also used in obtaining coal-bed methane and in underground coal gasification methods.Compared to holes with vertical axes, directional drilling is a much more complex issue. The curvature of the wellbore's axis, passing through the horizontally stratified rock mass, causes the conditions around its cross section to be strongly anisotropic. Not infrequently, the same rock material of each layer exhibits anisotropic properties. Ensuring the stability of the well is very difficult under such conditions.The proper determination of the state of stress, strain and displacement of the rock mass around the hole is critical in the design of directional holes. Numerical analysis tools which take into account the structure of the rock mass and the mechanical properties of rocks along the well trajectory are used for this purpose.The article presents numerical simulations of changes of the rock mass state around a directional well. The calculations were conducted with various material models of rock: the linear-elastic model, the linear-elastic with regard to pore fluid flow model, the elastic – plastic model, the Drucker-Prager cap model with pore fluid flow, the concrete damage plasticity model (CDP), and the cracked material model. The impact of primary pressure, lamination and anisotropy of the rock mass are also included in the calculation. Based on the results of the calculations we analyze the impact of the behavior of rocks on the wellbore's stability.

Qualitative modeling of multi-stage fractured horizontal well productivity in shale gas reservoir

As an important unconventional gas resource, shale gas has become an important part of gas production in recent years with the advantage of horizontal well drilling and large-scale multi-stage hydraulic fracturing completion technologies. The shale gas reservoir numerical simulation advances were reviewed and a multi-stage fractured horizontal well numerical simulation was performed to qualitatively modeling the well productivity in over-pressured shale gas reservoir based on actual shale properties and well completion parameters. A single horizontal well model was established on the basis of dual-porosity model and logarithmically spaced grid refinement. A comprehensive comparison and analysis of the initial average gas production, daily gas production, cumulative gas production, adsorbed gas and free gas cumulative production were provided to investigate the influence of matrix permeability, SRV permeability, hydraulic fracture conductivity and half length, SRV size, bottomhole pressure on the well performance. The research shows that for the high matrix permeability (Km > 10−7 mD) and low SRV permeability (KSRV < 0.01 mD), the SRV permeability has a significant impact on the initial average gas production. For the high matrix permeability (Km > 10−7 mD) and medium SRV permeability (0.01 mD < KSRV < 0.5 mD), the initial average gas production is controlled by both the matrix and SRV permeability. For the high matrix permeability (Km > 10−7 mD) and high SRV permeability (KSRV > 0.5 mD), the initial average gas production is mainly controlled by the matrix permeability. When the matrix permeability is lower than 10−9 mD, the cumulative gas production is too low to be of economic interest. For the matrix permeability (10−9 mD < Km < 10−5 mD), the matrix permeability and SRV permeability are all important factors that influence the cumulative gas production. For the matrix permeability (Km > 10−5 mD), the matrix permeability has much more impact on cumulative gas production than that of SRV permeability. The daily gas production and cumulative gas production are independent of hydraulic fracture conductivity and half length. The initial gas production of multi-stage fractured horizontal well is also independent of SRV sizes. The SRV size mainly controls the gas production decline characteristic. With the increase of the SRV size, the daily gas production declines slowly. The SRV size determines the cumulative gas production directly. With the increase of the SRV size, the cumulative gas production increases linearly. The bottomhole pressure has a significant impact on cumulative gas production. With the decrease of the bottomhole pressure, the cumulative gas production of 20 years increases linearly.

ECONOMIC VALUE OF MARCELLUS SHALE GAS IN THE DELAWARE BASIN

INTRODUCTION Through modernization of horizontal drilling and hydraulic fracturing technology, natural gas has become a plentiful, inexpensive, and relatively clean-burning domestic resource that p...

A feasibility study of thermal stimulation in unconventional shale reservoirs

Shale oil production from plays such as the Bakken and Eagle Ford, driven by advances in horizontal well drilling and hydraulic fracturing technology, has helped improve US domestic oil production. However, due to the low permeability of shale oil reservoirs, primary depletion only produces 5–10% of the original oil in place and there is a huge potential for improved recovery. Chemical and gas huff-n-puff have been piloted with varying degrees of success, but no breakthrough recovery method has been discovered.This study examines improved oil recovery from shale reservoirs by thermal stimulation, consisting of primary depletion (early in a well's life), followed by conversion of the well to a heat injector to elevate reservoir temperature, and finally followed by a secondary depletion. The proposed method was tested using a compositional, thermal reservoir simulator (CMG STARS) and key parameters affecting recovery during thermal stimulation were investigated.This study found that 1000 days of thermal stimulation with a 700°F heater has the potential to economically increase oil recovery from about 7% to more than 11.5%, with potential for even greater recovery if heat injection time and temperature are optimized. The study also found that thermal pressurization of oil is the primary mechanism for the improved recovery. Kerogen decomposition into oil and gas results in a significant increase of hydrocarbons in place but is only a minor contribution to the additional recovery because production is limited by a lack of flow capacity. Furthermore, a two-fold increase in permeability is observed as a result of kerogen decomposition, but its contribution to recovery is also minor because the heated region is not well connected with the fractured region. The heating scheme may be improved in the future to better connect the heated region with the fractured region.

Finding the Displacement of Elastically Bent Pipeline Disposed on Roller Supports Under the Action of the Axial Shear Force

The authors of this article have developed a spatial position determination method of a real steel pipeline free segment located above the ground surface during pipeline pullback using a pipeline pusher for the horizontal directional drilling technology. Values of elastically bent pipeline displacement were found in different points of the pipeline profile with the aim of defining the admissible values of the shear force applied to the pipeline by additional equipment during the pipeline pullback process. The developed methods allow finding the points of the curved pipeline profile in which it is necessary to place additional fixing connections above the pipeline, as this will expand the range of the shear force applied to the pipeline.

Delineating property rights in unconventional hydrocarbon resources: Concepts from the United States and Germany

The use of hydraulic fracturing (fracking) and horizontal drilling technologies for recovering unconventional hydrocarbons (oil and gas) has created issues concerning the rights of property owners, energy companies, and others involved with the development and distribution of these resources. Constitutional provisions, legislative statutes, and jurisprudence on liability in the United States and Germany affect rights to oil and gas resources and the profitability of developing these resources. Legal rules for trespass, the rule of capture, pooling, unitization, and municipal fracturing bans circumscribe property rights associated with shale gas development in the United States. Germany, until setting up a specific, long-term legal regime on hydraulic fracturing, will rely on existing mining, water, and environmental legislation (as most recently modified). The evaluation of the law and jurisprudence governing unconventional hydrocarbon development in the U.S. and Germany discloses perceptions and expectations that contribute to widespread extraction in the U.S. while Germany contemplates the safety of allowing hydraulic fracturing.

Design of in-pipe robot based on inertial positioning and visual detection

The horizontal directional drilling technology is widely used to lay the underground pipelines. These pipelines are of small or medium diameters with a dip angle ranging from 10° to 20°, special pipelines to 30°. In-pipe robot is commonly used to detect the pipeline fault. A new type of telescopic in-pipe robot is designed in this article, which is driven by step motor and screw, and supported by wheels. The robot has advantages of waterproof grade of IP68, stable motion state, and larger traction force. The speed is between telescopic robots and wheeled robots. Through force analysis and calculation, its maximum climbing angle is larger than 35°. The robot has good passing ability through the pipelines with bends. The inertial technology is used to locate the robot under the condition of disturbances. The pipeline fault detection algorithm based on the visual identification technology is designed to detect the pipeline fault. It can not only achieve autonomic positioning but also detect the pipeline fault.

Development of small diameter pilot hole directional drilling for trenchless utility installation

The paper overviews trenchless utility installation techniques and prospects of further development of horizontal directional drilling technology to drill small diameter pilot holes. The improved design is suggested for the thread connection of drill pipes and hydraulic system to generate power pulses.

Potential environmental impacts of ‘fracking’ in the UK

ABSTRACTHydraulic fracturing, or ‘fracking’, involves the extraction of natural gas from shale formations deep underground using vertical and horizontal drilling technologies and vast quantities of chemically treated water injected into the wells under high pressure. Although commercial fracking has been underway in the USA since the 1990s, the industry is in its infancy elsewhere in the world. Rapid increases in gas production in the US have spurred interest in countries as far flung as the UK, China, Poland, Argentina and South Africa, although there is much uncertainty over potential gains and the environmental costs of the new technology (Buchan, 2013; European Commission, 2012a). In the UK, there are currently no companies actively fracking but several are undertaking exploratory drilling, and many policymakers, academics, environmental activists and energy industry specialists feel that the UK could be on the edge of a ‘fracking boom’. Some see fracking as a potential energy bonanza ensuring the UK's energy security well into the future, while others fear that it could bring significant harm to the environment and public health. In this article, we explore several dimensions of these uncertainties generally, and assess specifically some of the implications for the UK water environment. We also suggest ways in which the UK could learn from the experiences of fracking in the USA.