bluuebunny/crossref_metadata_2025_split huggingface dataset:
Filtration in Frac-Packs and its Impact on Injector Performance
Authors: Hwang Jongsoo , Lehardi Samuel , Sharma Mukul M. 
Published: June 2014

Abstract
The filtration of solids in the injection water in a frac-pack is the primary factor which controls the injectivity decline in frac-packed water injection well completions. The injectivity may decline rapidly or much more slowly depending on the degree of frac-pack filtration. The widening and lengthening of frac-packs and the associated loss of sand control are affected as well. However, there is no experimental data for the filtration coefficient in high velocity flows in frac-packs. In this research, the filtration coefficients were experimentally measured in high velocity flows encountered in frac-packs. The solid concentrations and pressure drops across proppant pack sections were measured to properly utilize filtration theory and permeability decline models. The filtration coefficients were measured at various flow rates and for different proppant sizes. Our experiments show that at high fluid velocities, the filtration coefficient is significantly lower than that estimated from prior correlations that are based on low velocity filtration.
Our experimental results were used to obtain new empirical correlations for filtration coefficients at high flow rates in frac-packs. The experimental coefficients were used as the primary input into a well injectivity model. The proper estimation on the filtration enabled us to analyze the impact of injection rates and proppant selection on injector performance, i.e., predict longterm injection well behavior. The effect of particle filtration in the frac-pack and its effect on injector performance was captured accurately for the first time. The empirical correlations together with a model for frac-pack growth in the injection well allowed us to accurately estimate fracture dimensions and the long-term water injectivity of frac-packed injectors. These results can be used for frac-pack design, proppant selection and specification of injection water quality.
First Offshore Coiled Tubing Intervention Using a Catenary System in the Gulf of Mexico
Authors: Huerta Juan Martin , Lara Ricardo Ramirez , Marin Marlon , Kowalski Ricardo , Franco Ernesto , Ortega Ruben , Ponce Gabriel , Hernandez Daniel , Ramos Jaime 
Published: June 2014

Abstract
Coiled tubing (CT) operated from a floating anchored vessel (FAV) was developed for well intervention in offshore locations where crane limitations and deck loading constrains imposes various limitations on the ability to perform workover operations. This tailor-made solution involves the operation of a CT unit with the tubing reel located on a FAV and the injector head positioned on the offshore platform. Today, CT operations supported by a FAV are routinely performed in several countries, including Malaysia, Gabon, Tunisia, Brunei, Angola and the North Sea.
The first CT operation supported with a vessel in the Gulf of Mexico was successfully performed in a non-producing well which had been shut-in for nine months due to compatibility issues with the structure for temporary installing service equipment and and the limited availability of jack-up platforms to provide a deck area for positioning CT equipment. As result of this successful operation, a new perspective of CT rigless interventions was adopted in offshore Mexico, thus allowing the operator to improve equipment utilization for both CT units and workover rigs, in order to maximize oil production.
This paper details the analysis, execution and evaluation of the first CT operation from a FAV in offshore Mexico, which includes equipment selection, sea condition and weather-related studies, contingency planning, personnel competency and training requirements, and logistical considerations, among other technical factors that were critical in the implementation of such project. As well, the benefits that were realized by the operator regarding production enhancement and operational cost reduction are covered.
CT Extended Reach: Can We Reach Farther?
Authors: Newman Ken , Kelleher P.E, Patrick , Smalley Ed 
Published: June 2014

Abstract
The ability to perform extended reach operations with coiled tubing (CT) has become increasingly important in recent years as a result of the increased length of horizontal wellbores. Fracturing horizontal wells in stages often requires the use of drillable bridge plugs or sliding sleeves, which are drilled out or slid with CT. As the length of the horizontal section of a wellbore continues to be extended (known as extended reach), the reach of CT also needs to be extended. Drillpipe is able to reach farther than CT due to its ability to rotate (which mitigates sliding friction). The inability of CT to rotate makes extending the reach more challenging.
This paper presents the theory and modeling which helps determine the maximum reach in a horizontal well before helical lockup occurs. It presents a parametric study for an L shaped well which shows the significance of each parameter in extending the reach. A new tapered CT string concept referred to as "Extended Taper™", is presented.
Case Study of New Technology Introduction: Through Tubing Zonal Isolation with an Expandable Plug in Dual Completion Well
Authors: Al-Jasmi Ahmad Kh. , Choudhuri Amit , Desai Sameer Faisal 
Published: June 2014

Abstract
Kuwait Oil Company (KOC) had major issues in resolving problems of controlling water production from long strings in dual 9-5/8" completion wells. An economic process of zonal isolation was being investigated by the Company since conventional process of mobilizing a work over rig is expensive and would also result in loss of production from the short string of the well during the workover job. Many technologies through tubing had been tried earlier but did not succeed in positive isolation on a consistent basis. This was a technology challenge presented to Research and Technology Group for identification of a suitable technology. On review of various technologies, it was decided to pilot trial HIP plug from a service provider in one of the dual completion well of KOC. The pilot trial was planned to test functionality and integrity of the plugging process in isolating the bottom zones of the wells by intervening thru tubing.
This paper would exemplify KOC’s new technology identification process, selection, pilot project execution process, trial validation and determination of success criteria.
Casing Patches Used to Temporarily Shut Off Reservoirs
Authors: Wilczek P. , Oberascher R. , Osmanovic A. 
Published: June 2014

Abstract
Remedial operations on high permeable und underbalanced reservoirs can become risky. Lack of an exact liquid level, tight clearances leading to a high ECD and old unreliable reservoir characteristics can result in a fast liquid loss situation occurring out of view. Good mud properties can handle this issue but an instable filter cake can quickly lead to a situation where the formation will be filled with cement while your secondary liner is still uncemented. This situation is irreversible and in the worst case may even stay unnoticed.
Casing patches, which are thin steel liners tightly pressed against the inside wall of a casing and designed for zonal isolation and casing leak treatment, can be an efficient remedy for these type of problems. Used on perforated reservoirs they provide a stable and reliable temporary barrier during a workover. The reservoir is reopened using conventional perforating guns once the workover is finished. Since the patches are non-invasive, no additional reservoir damage can be expected.
Within the fields of GDF SUEZ Germany Exploration & Production (DExPro) this technique has been used successfully on three wells in 2011. Two of these wells required a secondary liner and one needed to be hydraulically fractured in order to overcome strong reservoir damage. All three had significant issues that made a conventional workover approach risky. The casing patch technology provided reduced contingency in the workover plan and provided an excellent protection of the fragile reservoir environment.
Milling PosiSet Plugs with Coiled Tubing to Remove Zonal Isolation
Authors: Hester J. , Gil C. , Torres M. 
Published: June 2014

Abstract
As part of the old time reservoir strategy to develop the Cusiana field in Colombia, PosiSet Plugs were set on Electric Line with cement on top mainly for Gas Shut Off purposes. In the recent years, it was necessary to remove the isolation to comply with the updated reservoir strategy to produce the lower reservoirs. Instead of a Workover rig intervention for cost optimization, Coiled Tubing was used to mill the cement, mill and push the PosiSet Plug and reestablish access and production of previously isolated zones.
At the beginning there were not many case stories of PosiSet Plug milling worldwide and several difficulties were observed in the first attempts. Milling time was high and not all interventions were successful. However a robust learning curve was created allowing the current removal of PosiSet Plugs without major difficulty in terms of hours. Tools used and operational procedure represents the key points of the implemented strategy.
Isolation of Water Producing Interval in a Horizontal Well Completed with Multistage Fracturing System Using Two CT Inflatable Bridge Plugs
Authors: Burdin K. V. , Mazitov R. N. , Bravkov P. V. , Serikov D. A. , Klimenko V. N. , Zhuk V. , Golovanev A. S. , Potryasov A. A. , Kovalev V. N. , Yunusov R. R. 
Published: June 2014

Abstract
The widespread application of multi-stage fracturing technology in Russia is already known not only due to increase of production rates and increase of recoverable reserves but also due to premature water flooding of some intervals. Several reasons could lead to that result, while, perhaps, the main one is a breakthrough in the aquifers in the process of the fracturing.
Objective of the job given by the client was to isolate water producing interval in a horizontal well completed with 8-stage MSF completion. To determine position of water-flooded zone, coiled tubing production logging tool (PLT) was used. Based on CT logging data 6th frac port of 8-stage MSF completion was found to be water flooded. Moreover, while total production rate of the well was equal to 500 m3/day (data was received during nitrogen lift while logging) with 95% WC, 68% of total production came from 6th frac port.
This article includes detailed study of planning process, complex and unambiguous decision-making aimed at technical and practical challenges, risk assessment and methods to reduce them, the stages of the work and planning in different situations that arise in the process of water shut-off and received lessons learned.
Composite: Is Multi-Plug Milling That Fast?
Authors: Cromer C. M. , Aviles I. , Li N. 
Published: June 2014

Abstract
Multi-stage stimulation by use of composite plugs (CP) for isolation has been in practice for over 15 years in North America. It continues to be a cost effective solution for shale plays requiring hydraulic stimulation of horizontal wells. Currently, there are dozens of plug venders in North America that supplied hundreds of thousands of plugs to the market. In order to perform effectively, plugs must convey down long horizontal wells, deploy at the appropriate depth in a well, hold pressure during a frac, and be removed utilizing conventional wellbore cleanout techniques, which in most areas involve milling with coiled tubing. The milling aspect of designing a plug can be particularly challenging, as it can be difficult to simulate without conducting a full scale test. Additionally, there are many different types of bits or mills to choose from. Thus, testing is required when designing a plug to optimize milling performance. Failure to do so can result in increased milling time and cost, something unacceptable in these tight-economic plays.
Mill out testing during the qualification phase is key to the plug performance in real bottomhole conditions. Multiple plugs are used in a single well that ideally will be milled out sequentially. Thus performing a mill test with only one plug may result in an optimistic view of plug milling. There are several important parameters in evaluating milling performance or millability in a test, including: overall millout time, penetration rate, debris size, and stump size. The millout time per plug in a well is defined as the average time taken to mill through a single plug, starting when the mill contacts the top of the plug and ending when the plug‟s anchoring mechanism gives way. This leaves the bottom part, or stump, un-milled. The shape and size of the stump may significantly affect how the debris is conveyed to the next plug as well as the milling of the next plug. Millout time must calculate as an average of no less than two plugs milled in sequence.
This paper will describe the best practices for determining the millability of a CP in a multiple plug scenario, and show how milling tests can be used to improve the design of a plug and optimize mill selection. This in turn maximizes the chances of successfully and efficiently removing CPs in the multi-zone treatment application, with the overall goal of improving the economics of these wells.
Adaptability of Coiled Tubing Technology Enables Complex Well Abandonment in Gulf of Mexico Inland Waters
Authors: Webb B. , Rudnik A. , Bonin B. , Crider K. 
Published: June 2014

Abstract
An operator drilled an inland waters well in the 1960’s in southern Louisiana. By the time the well was scheduled for plug and abandonment (P&A), the canal had been transformed into wetlands and significant silt had built up around the wellhead, thus increasing the complexity of the abandonment operations. The environmental impact to the wetlands would be minimized by laying mats around the well in preparation for coiled tubing (CT) operations. However, these mats laid out on the soft wetlands would not safely support the excessive weight of the CT unit and reel, so they were rigged up on a barge 125-ft away from the wellhead. A CT drilling tower was used to provide stability to the wellhead stack. The wellbore conditions (11,300 psi MASP and 313 deg F BHT) increased the complexity of this operation further, requiring a very thorough job planning process. A mock rig-up of equipment was performed before mobilizing equipment to location to ensure the stability of the wellhead stack. The CT operations were completed successfully which allowed the operator to complete the decommissioning of the well. This paper presents a case study that demonstrates the adaptability of CT technology to meet the special requirements of well abandonment in the inland waters environment of the Gulf of Mexico.
A History of Gas Lift Valve and Gas Lift Mandrel Damage and Subsequent Retrofit Gas Lift Straddle Installation in Alaska
Authors: Julian J. Y. , Jackson J. C. , White T. M. 
Published: June 2014

Abstract
In Alaska oilfields, non rig tubing repair has become a viable alternative to rig workovers (RWO). Tubing straddles can remediate tubing by casing ("A" annulus) communication at a tremendous savings in areas where rig workover cost is significant. This paper advances the analysis of more than 400 tubing straddles set since 1985. SPE paper 104055 showed that the majority of straddles were installed over damaged gaslift valves and gaslift mandrels. Damage to a gaslift valve can occur when it is eroded (or flow cut) due to fluid unloading of the casing by tubing annulus through the gaslift valve. This leads to tubing by "A" annulus communication which usually requires that the damaged gaslift valve be replaced. However, if the gaslift valve has been flow cut and is not replaced immediately, the gaslift mandrel itself, which is a part of the tubing completion, can be subsequently flow cut, requiring tubing replacement or tubing straddle installation. This paper will update the results of the straddle study on a large gaslifted field to quantify the signifance of the problem. It will not only discuss the history of wells that required a straddle to repair gaslift valve or mandrel damage, but will also analyze wells that only required a gaslift valve replacement to repair tubing communication due to a damaged gaslift valve.
The paper will also describe the use of retrofit gaslift straddles in 3-1/2" thru 7" tubing sizes, including lessons learned. Retrofit gaslift straddles are a subset of tubing straddles. They are particularly attractive in areas where rig workover cost is significant, such as offshore, remote, or arctic locations. Most significantly, the paper will discuss a commercially available barrier gaslift valve, why it is superior to conventional gaslift valves and upcoming installation plans in Alaska to prevent gas lift valve damage and subsequent gaslift mandrel damage.
Collaborative Industry Initiative to Assess Potential Health Effects Related to the Production of Unconventional Resources
Authors: Devlin D. J. , Beatty P. , White R. D. , Naufal Z. , Sarang S. S. 
Published: June 2014

Abstract
Unconventional resources offer many substantial benefits as energy sources and chemical feedstocks. Natural gas is abundant, affordable, clean burning, increases energy security, and provides significant economic benefits at local and national levels. Yet, the rapid increase in production of these resources from unconventional shales using the process of hydraulic fracturing has generated scrutiny by some policymakers and advocates who cite health concerns. The industry, through the American Petroleum Institute (API), is taking steps to assess all legitimate health concerns, communicate our findings, and ensure that public health is adequately protected. API recently formed the Exploration and Production (E&P) Health Issues Group to provide research, scientific analysis, and guidance on health issues regarding Unconventional Resource Production (URP). The Group is particularly focused on community health concerns, including those associated with the compositions of hydraulic fracturing fluid and flowback, aquifer impacts, air emissions, and psycho-social stress related to operations. URP is an industrial activity that carries benefits and potential risks, similar to conventional resources. The risks must be identified, assessed and effectively managed. The work being performed and communicated by this API Group will help to ensure that any potential health risks from production of unconventional resources are identified, evaluated, appropriately communicated, and managed to enhance public confidence and ensure protection of public health.
Fracture Propagation, Fluid Flow, and Geomechanics of Water-Based Hydraulic Fracturing in Shale Gas Systems and Electromagnetic Geophysical Monitoring of Fluid Migration
Authors: Kim Jihoon , Um Evan Schankee , Moridis George J. 
Published: June 2014

Abstract
We investigate fracture propagation induced by hydraulic fracturing with water-injection, using numerical simulation. For full 3D rigorous modeling, we employ a numerical method that can model failure due to tensile and shear stresses, dynamic nonlinear permeability, the dual continuum approach, leak-off in all directions, and thermo-poro-mechanical effects. From the numerical results, fracture propagation is not the same as propagation of the water front, because fracturing is governed by geomechanics, whereas water saturation is determined by fluid flow. At early times, the water saturation front is almost identical to the fracture tip, showing that the fracture is mostly filled with injected water. However, at late times, advance of the water front is retarded, compared to the fracture propagation, yielding a significant gap between the water front and the fracture top, which is filled with reservoir gas. We also find considerable leak-off of water to the reservoir. The inconsistency between the fracture volume and the volume of injected water cannot properly estimate the fracture length, when it is estimated based on the simple assumption that the fracture is fully saturated with injected water. As an example of flow-geomechanical responses, we identify pressure fluctuation under constant water injection, because hydraulic fracturing is itself a set of many failure processes, in which pressure drops every time when failure occurs. The fluctuation decreases as the fracture length grows.
We also study application of electromagnetic (EM) geophysical methods, because the EM geophysical methods are highly sensitive to changes in porosity and pore-fluid properties, such as water injection into gas reservoirs. We employ a 3D finite-element EM geophysical simulator and evaluate the sensitivity of the crosswell EM method for monitoring fluid movements in shaly reservoirs. For the sensitivity evaluation, reservoir models are generated through the coupled flow-geomechanical simulator and are transformed via a rock physics model into electrical conductivity models. It is shown that anomalous conductivity distribution in the resulting models is closely related with injected water saturation but little with newly-created unsaturated fractures. The numerical modeling experiments demonstrate that the crosswell EM method can be highly sensitive to conductivity changes that directly indicate the migration pathways of the injected fluid. Accordingly, the EM method can serve as an effective monitoring tool for distribution of injected water (i.e. migration pathways) during hydraulic fracturing operations.
Fully-Coupled Numerical Evaluations of Multiwell Completion Schemes: The Critical Role of In-Situ Pressure Changes and Well Configuration
Authors: Nagel N. , Sheibani F. , Lee B. , Agharazi A. , Zhang F. 
Published: June 2014

Abstract
The development of many shale plays has been met with significant challenges, including low production rates and rapid production declines, and many ideas and concepts have been tried to address these. Multi-well completions, like ‘Simulfracs’ and ‘Zipper fracs’ for example, have been attempted as a means to increase production, but these have met with only limited success.
The authors have shown in previous work that multi-well completions increase the in-situ stress field around the created hydraulic fractures, which has the effect of stabilizing natural fractures and weakness planes (making them more resistant to shear). Further, the authors have also shown in previous work that the increase in shear from the tip of propagating hydraulic fractures, in a Zipper frac multi-well completion for example, is a complicated factor of well spacing, frac spacing, hydraulic fracture length (for a given well spacing), natural fracture mechanical properties, and in-situ stress.
In this paper, we present the results of a discrete element model numerical study of multi-well completions simulated in a fully hydro-mechanical coupled fashion. Building upon the previous work of the authors and others, the influence of changes in the in-situ pressure are considered in order to more completely understand the mechanical interactions between propagating hydraulic fractures and natural fractures during multi-well completions. The study includes a parametric study of well configuration, in-situ stress conditions, in-situ pressure, and mechanical properties on the ability to enhance natural fracture shear from multi-well completions and increase hydrocarbon production.
The quantitative results of the study provide a direct means to consider when multi-well completions may help increase hydrocarbon production. Further, the results of the study also provide a means to optimize the application and design of multi-well completions as a function of the in-situ stresses, in-situ pressure, the mechanical properties of the natural fractures and weakness planes, and well configuration, which, ultimately, should lead to improved well economics.