bluuebunny/crossref_metadata_2025_split huggingface dataset:
Using Drill Pipe Connection Continuous Circulation Technology on a Geothermal Drilling Project in Indonesia to Reduce Stuck Pipe Events
Authors: Pinkstone H. , McCluskey T. , MacGregor A. , Scagliarini S. , Indrinanto Y. 
Published: October 2018

Abstract
A drill pipe Continuous Circulation Device (CCD) system was used by a geothermal operator in Indonesia, with this paper's scope as follows: Demonstrate CCD system performance used to successfully drill two wells to section Total Depth (TD) with reduced Non Productive Time (NPT) related to stuck pipe events;Highlight the engineering design modifications of the CCD system to cope with the harsh and challenging geothermal drilling environment, through the application of lessons learnt and the use of statistical data. These design enhancements to the CCD, provided a robust method for reducing drilling risks and improved operational performance.
The CCD system was used to successfully drill two wells: a total of seven hole sections were drilled from 17 ½" to 7 7/8" in diameter at two geothermal well sites in the same field, onshore Java. The use of the CCD system allowed the rig to maintain constant flow rate of drilling fluid down the drillstring during drill pipe connections. This is paramount to prevent stuck pipe events when total drilling fluid losses are experienced especially in geothermal wells due to their inherent subsurface geological complexity coupled with the risks of formation breakout collapse typical of geothermal well down hole environments. Maintaining dynamic wellbore conditions through circulation and maintaining constant hole cleaning prevents pack offs due to cuttings and formation breakout cavings, settling, and dropout.
The harsh geothermal drilling environment required the CCD system to be modified to operate with higher circulating flow rates and high levels of Lost Circulation Material (LCM) in a total mud losses scenario. The CCD system was developed accordingly through lessons learnt analysis and application, root cause identification, and management of change processes to provide engineered solutions, which were then field tested. The application of this technology improved project economics by reducing NPT related to stuck pipe events and helped in the avoidance of stuck pipe events escalation, resulting in expensive fishing jobs and, potentially, Bottom Hole Assemblies (BHA) lost in hole with consequent sidetracks and associated cost impact.
High Definition Reservoir Multi Boundary Mapping Delivered Highly Productive Horizontal Well in Challenging Clastic Reservoir and Faulted Area
Authors: Rane Nitin , Alshammari Baraa Sayyar , Al-Sabea Salem , Wenang Martine , Juyal Mukul , Keot Chandan Jyoti 
Published: October 2018

Abstract
With the advent of new age real time drilling technologies, the amount of data generated downhole has increased tremendously. Complemented by superior telemetry, the ability to transfer data uphole has increased by many folds too. With the introduction of new generation geosteering and reservoir mapping applications, it is possible now to integrate conventional logs with deep directional electromagnetic resistivity and advance formation evaluation measurements for accurate bed mapping, real time assessment of reservoir quality, structural dip calculation and forward planning trajectory – all in an integrated and single platform. The result is informed decisions and highly optimized results. The paper will discuss on a case study using this innovative integrated platform where geologists, drillers and geosteering engineers worked in sync to come up with the best possible real time decisions for optimum well design and placement, in a clastic reservoir, reducing overall well construction risks and negotiating the challenges of undesired geological events like trajectory drilling through a fault.
The interpretation of deep directional electromagnetic propagation measurements via highly sophisticated inversion algorithms gives information on the spatial position of the wellbore w.r.t reservoir boundaries. The remote detection of boundaries up to 20 ft around wellbore, gives us the edge for trajectory forward planning by predicting upcoming structural trend, in other words called Proactive GeoSteering. Conventional logs combined with high end measurements like spectroscopy, sigma, source less density and neutron provide accurate real time formation evaluation while drilling which enhance decision making of geo-steering process. Availability of these high-end technologies would allow operators to place horizontal well as close as possible to top reservoir, optimizing long term well performance by minimizing attic oil and delay water production.
The case study represents how latest state of the art real time drilling technologies coupled with advance geosteering techniques successfully helped overcoming various geological uncertainties encountered while drilling a horizontal well. Unexpected minor sub-seismic fault was successfully mitigated which avoid undesired non-productive time and lost productivity of the well. The results were very encouraging in terms of well production, and optimum placement of the horizontal well which will enhance long term recovery.
This paper provides new insight on successful application of multi boundary mapping technique in optimizing well placement in top part of the reservoir and offers approach for drilling horizontal wells in similar case of complex clastic reservoir. The technique also discusses mapping of sub-seismic faults that cannot be identified by normal seismic data, and how to mitigate subsequent risk of the fault.
A Coupled CFD-DEM Numerical Study of Lost Circulation Material Transport in Actual Rock Fracture Flow Space
Authors: Feng Y. , Li G. , Meng Y. 
Published: October 2018

Abstract
Fractures are beneficial to the cost-effective development of unconventional reservoirs, which may also induce drilling fluid loss, formation damage and other issues. Fracture plugging is the most common measures to settle those problems. The effect of fracture plugging largely depends on the lost circulation material (LCM) formula. In order to form the plugging zone rapidly in the near wellbore portion of fracture, it is necessary to study the transport process of LCM in real fracture. In this paper, the distributions of fracture aperture of a tight sandstone specimen are captured utilizing the high-resolution and high-precision structured light scanning systems, which is used to reconstruct the geometric model of actual rock fracture flow space. The coupled Computational Fluid Dynamics and Discrete Element Method (CFD-DEM) simulation is carried out to study the interaction between drilling fluid and LCM particles as well as LCM transport in above geometric model with various particle size. The constant directional torque (CDT) model is employed in the part of DEM computation to account the influence of LCM particle shape. The numerical simulation results show the LCM particles would plug in the narrow region of the actual rock fracture flow space, inducing the rapid accumulation of other LCM particles. The compatibility between the distributions of fracture aperture and the size of LCM particles played a decisive role in the transport process of the LCM particles, which directly determined the position of plugging zone. The multigrain bridging phenomenon of small size LCM particles was observed in simulations. This paper presents the idea of combining the reconstruction technique of actual rock fracture flow space and the CFD-DEM simulation to mimic the transport process of LCM particles in real rock fracture. The simulation results show the fracture surface topography has a significant influence on LCM particles transport and plugging zone distribution; the LCM particles considering the nonsphericity may multigrain bridge in the fracture which will greatly improve the efficiency of fracture plugging.
Conical Diamond Element PDC Bit as a Breakthrough to Drill Hard Geothermal Formation in Indonesia
Authors: Gunawan Fatah , Krisnanto Widoyo , Mardiana M. R. , Noviasta Bonar , Febriarto H. B. 
Published: October 2018

Abstract
In geothermal drilling application, one of the challenges faced by drilling engineers is the optimization of drilling bit which govern the key success of drilling performance. It should be aligned with recent key performance indicator such as meet the subsurface target comprehensively while optimizing the drilling cost. A typical formation in geothermal wells that consists of various types of volcanic and igneous rock should be identified carefully because the high range of hardness and abrasiveness value will respectively affect the bit. Hence, the improvement of conventional drilling bit should be carried out to enhance the drilling performance.
For so many years, Tungsten Carbide Insert (TCI) bits were implemented in the geothermal drilling application because it is believed to be the most effective bit to drill hard formation. However, the TCI bits are limited by the maximum revolution the bit can achieve before the bearing seal fails. In some application, it needs 3 to 4 TCI runs to finish 9.875-in section. Some of the bits were also pulled out of the hole with undergauged condition due to formation abrasiveness. Implementing a conical diamond element (CDE) on a PDC can increase the bit durability. CDE provides significant improvement of wear and impact resistance to the bit. The point loading of this cutter is more concentrated to the formation, allows the bit to remove the rock in more efficient way. It has been discussed that the CDE bit can improve the ROP and meterage drilled, eliminating the tripping time due to bit changes as it does not have KREV limitation, and has a better trajectory control.
Usually, 3-5 TCI bits were used to drilled 9.875-in section in one of geothermal well located in Hululais Field, Sumatera, with average meterage of 200 – 250 m per bit. Drilling dynamics FEA modeling was performed prior to the run of CDE bit to check the drill string vibration and provide stable drilling parameter roadmap for this bit. A CDE bit was run to drill this section and the result was excellent by drilling 600 m in a single run. The ROP was improved by around 35% compared to the maximum TCI's ROP. The bit generated less reactive torque fluctuation compared to TCI, allowed the bit to have better directional control. The CDE bit was pulled out of the hole with good dull grading (2-1-WT-A-X-I-CT-TD). By improving the ROP and eliminating the tripping time, the drilling cost can be reduced.
With the downturn of oil and gas business, geothermal projects in Indonesia is raising. CDE bit is becoming a breakthrough to optimize the drilling operation in by substituting TCI runs with huge amount of potential cost savings.
Development of a New Mathematical Model To Quantitatively Evaluate Equilibrium Height of Proppant Bed in Hydraulic Fractures for Slickwater Treatment
Authors: Hu Xiaodong , Wu Kan , Song Xianzhi , Yu Wei , Zuo Lihua , Li Gensheng , Shen Zhonghou 
Published: October 2018

Summary
The proppant bed develops and its height grows until it reaches the critical velocity and equilibrium height. This paper proposes a comprehensive mathematical model to evaluate the equilibrium height for slickwater treatment. We use well-accepted published experimental data and models from other groups to validate our model. After that, we investigate the effects of proppant properties and fluid properties on the equilibrium height. This work can provide critical insights to optimize the design of proppant parameters in a hydraulic fracture. Meanwhile, this model can be incorporated into fracture-propagation simulators for simulating proppant transport.
Insights Into Rock Typing: A Critical Study
Authors: Ghanbarian Behzad , Lake Larry W. , Sahimi Muhammad 
Published: October 2018

SummaryVarious methods that link a representative pore-throat size to permeability k and porosity ϕ have been proposed in the literature for rock typing (i.e., identifying different classes of rocks and petrofacies). Among them, the Winland equation has been used extensively, although when it was first proposed, it was based on experiments. Because of its empiricism, the interpretation of the parameters of the Winland model and their variations from one rock sample or even one rock type to another is not clear. Therefore, the main objectives of this study are (1) to propose a new theoretical approach for identifying rock types that is based on the permeability k and the formation-resistivity factor F and (2) to provide theoretical insights into, and shed light upon, the parameters of the Winland equation, as well as those of other empirical models. We present a simple, but promising, framework and show that accurate identification of distinct petrofacies requires knowledge of the formation factor, which is measured routinely through petrophysical evaluation of porous rocks. We demonstrate that, although some rock samples might belong to the same type on the k-vs.-1/F plot, they might appear scattered on the k-vs.-ϕ plot and, thus, could seemingly correspond to other types. This is because both k and F are complex functions of the porosity, whereas the porosity itself is simply a measure of the pore volume (PV), and does not provide information on the dynamically connected pores that contribute to both k and F. We also show that each rock can be represented by a characteristic pore size Λ, which is a measure of the dynamically connected pores. Accurate estimates of Λ indicate that it is highly correlated with the permeability.
The Description and Quantification of the Truncation Errors Produced by Local-Grid Refinement in Reservoir Simulation
Authors: Tijink Paul , Cottier Juan 
Published: October 2018

SummaryGeologically realistic 3D models yield nonorthogonal simulation grids as a result of grid distortion at faults, steeply dipping horizons, and zonal truncations. Finite-difference (FD) simulators applying discretization principles and volumetric flux calculation use two-point flux approximation (TPFA). On nonorthogonal grids, the TPFA causes numerical errors in the solution of pressure and saturation such that simulation results become inaccurate. These inaccuracies are known as grid-orientation effects.This paper will demonstrate that TPFA applied to grids containing local-grid refinement (LGR) causes identical numerical errors. In the case of a vertically partial LGR, the numerical errors become so severe that they invalidate the simulation results. These results include unphysical oscillations in the fluxes within the LGR and unphysical baffles to flow at the interface between the coarse grid and the LGR.The invalidation of simulation results is demonstrated by two case studies involving the history matching of well tests. To avoid invalid simulation results, any LGR applied in a grid must be extended over the entire vertical extent of the grid such that there exists no TPFA between the coarse- and the refined-grid cells in the vertical direction.
Elevated-Temperature and -Pressure Tribology of Drilling Fluids Used in Oil and Gas Extended-Reach-Drilling Applications
Authors: Lan Pixiang , Polychronopoulou Kyriaki , Iaccino Larry L. , Bao Xiaoying , Polycarpou Andreas A. 
Published: October 2018

Summary
Extended-reach-drilling (ERD) wells are expensive and challenging; however, in special situations, compared with conventional drilling, ERD wells are more environmentally friendly and cost-effective. Application of drilling fluids with good lubrication for ERD is one of the most important methods to facilitate longer total depth (TD) of the wells. To better simulate the elevated-temperature environment in the borehole, this study proposes a method to perform tribological studies of drilling fluids at temperatures higher than 100°C by conducting experiments in a high-chamber-pressure environment, which can suppress the evaporation of the drilling fluid at high temperatures. Two lubricant additives were studied, and the results showed that, for the drilling fluid at elevated temperatures, a prototype additive (Additive A) reduced the coefficient of friction (COF) significantly by 44.8%, whereas a commercial additive (Additive B) caused only a slight reduction of the COF by 4%. After the tribological experiments, the wear mechanisms of the additives and abrasive particles were investigated with scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS).
Optimizing Jet-Pump Production in the Presence of Gas
Authors: Kurkjian Andrew L. 
Published: October 2018

Summary
A hydraulic jet pump with both gas and liquid phases at the intake is modeled analytically. A complete system model results when this is combined with models of the surface pump, tubing, casing, and the pressure/temperature behavior of oil and gas. This model is used to size jet pumps before installation and to optimize production. Production optimization includes first estimating the pump-intake pressure and then determining the drive frequency for the surface pump that minimizes the pump-intake pressure. There is an optimal frequency at which the intake pressure is minimized and production is maximized.
Uncertainty Quantification of the Fracture Network with a Novel Fractured Reservoir Forward Model
Authors: Chai Zhi , Tang Hewei , He Youwei , Killough John , Wang Yuhe 
Published: October 2018

Abstract
A major part of the uncertainty for shale reservoirs comes from the distribution and properties of the fracture network. However, explicit fracture models are rarely used in uncertainty quantification due to their high computational cost. This paper presents a workflow to match the history of reservoirs with complex fracture network with a novel forward model. By taking advantage of the efficiency of the model, fractures can be explicitly characterized, and the corresponding uncertainty about the distribution and properties of fractures can be evaluated. No upscaling of the fracture properties is necessary, which is usually a required step in a traditional workflow.
The embedded discrete fracture model (EDFM) has recently been studied by many researchers due to its high efficiency compared to other explicit fracture models. By assuming a linearly distributed pressure near fractures, EDFM can provide a sub-grid resolution that lifts the requirement to refine near the fractures to a comparable size as the fracture aperture. Although efficient, considerable error is reported when applying this method to simulate flow barriers, especially when dominant flux direction is across instead of along the fractures. In this work, a novel discrete fracture model, compartmental EDFM (cEDFM) is developed based on the original EDFM framework. However, different from the original method, in cEDFM the fracture would split matrix grid blocks when intersecting them. The new model is benchmarked for single phase as well as multi-phase cases, and the accuracy is evaluated by comparing to fine explicit cases. Results indicate the improved model yields much better accuracy even for multi-phase flow simulation with flow barriers.
In the second part of the work, we applied the model in history matching and performed uncertainty quantification to the fracture network for two synthetic cases. We used Ensemble Kalman Filter (EnKF) as the data assimilation algorithm due to its robustness for cases with large uncertainty. The initial state does not need to be close to the truth to achieve convergence. Also EnKF performs well for the history matching of reservoirs with complex fracture network, where the number of parameters can be large. Therefore, it is advantageous compared to using Ensemble Smoother (ES) or Markov Chain Monte Carlo (MCMC) for fractured reservoirs. After the final step of data assimilation, a good match is obtained that can predict the production reasonably well. The proposed cEDFM model shows its robustness to be incorporated into the EnKF workflow, and benefit from the efficiency of the model, this work made it practical to perform history matching with explicit fracture models.
The Challenges of Deploying an MPD System on a MODU to Drill Narrow Margin Shallow Horizontal Wells in DW GoM
Authors: Moghazy Sharief , Smelker Keith , Hernandez Julian , Van Noort Roger , Arnone Maurizio 
Published: October 2018

Abstract
Managed Pressure Drilling (MPD) is an existing technology that is emerging in Deepwater drilling operations. This paper provides a case study from the Operator’s view, of preparing and deploying an MPD Surface Back Pressure (SBP) system for use in a shallow horizontal well with narrow drilling margins in 8,000ft water depth in the Gulf of Mexico.
This paper will describe the engineering, preparations and operational challenges of deploying a Below Tension Ring (BTR) MPD system. The paper will also include information on the hazard assessments, Mud Gas Separator (MGS) considerations, training plan, deployment plan and results, and engagement with the regulator.
The paper will present a case for the requirement of MPD for use in the narrow margin shallow horizontal wells, including an analysis of the required mud weights and surface back pressure to drill through narrow margins. It will also include a summary of best practices and lessons learned.
A New Technique for Quantifying Pressure Interference in Fractured Horizontal Shale Wells
Authors: Chu Weichun , Scott Kyle , Flumerfelt Ray , Chen Chih-Cheng 
Published: October 2018

Abstract
Pressure communication is commonly observed in fractured horizontal shale wells, particularly at early times when wells are placed on production. This paper will present a new technique, based on the diffusion exponent from the power-law model, to quantify connectivity in multi-stage hydraulic fractured wells with complex fracture networks. In addition to explaining the theory and analysis techniques, we will present examples utilizing measured bottom-hole pressure (BHP) from the Permian Basin Wolfcamp Shale, which illustrate the utility of this technique to better understand the relationship between completion size, well spacing, and well performance.
Chen and Raghavan (2015) recently developed a one-dimensional, fractional-order, transient diffusion equation to model fluid flow in complex geological media. They showed power-law behavior is the norm in unconventional reservoirs such as Permian Basin Wolfcamp Shale. Under the framework of power law behavior, we plot pressure interference test (PIT) data in terms of the Chow Pressure Group (CPG), which enables us to define an indicator of connectivity reflecting temporal and spatial effects. On each test, we derive a diffusion exponent reflective of the magnitude of pressure interference (MPI). We will show among other things that multiple PITs over time often indicate degrading connectivity between wells.
From PIT analyses in Permian Basin Wolfcamp Shale, we were able to establish a relationship between MPI and well spacing. The first example demonstrates analyses of PITs between wells during the production phase and also shows how connectivity between wells diminishes over time. A second example applies the same analysis techniques to quantify inter-well connectivity during the post-stimulation phase by analyzing a pressure falloff (PFO) after communication with other wells. A third example illustrates an application of desuperposition to remove the effect of a power-law pressure trend on interference tests.
Techniques to analyze PITs assuming radial or linear flow have been previously developed; however, Raghavan and Chen (2018) showed apparent radial or linear flow could exist under anomalous diffusion for heterogeneous reservoirs. In this work, we present a technique for analyzing power-law PIT data, which is typical of most horizontally fractured shale wells. This model is a unique approach to understanding flow behavior, quantifying well interference, and analyzing & predicting well performance in unconventional reservoirs. Our examples, which are based on high-quality BHP gauge data, show how this technique could shorten the cycle time for operators to determine the well spacing for a given completion design.