bluuebunny/crossref_metadata_2025_split huggingface dataset:
Extending the Limit: Interval Pressure Transient Testing in Low-Permeability Reservoirs in the North Sea
Authors: Samuelsen Eivind , Gisolf Adriaan , Seri Gerardo , Eriksen Kåre Otto 
Published: October 2009

Abstract
The use of wireline-conveyed formation testers for sampling, downhole fluid analysis (DFA), interval pressure transient testing (IPTT), and producibility estimation is well established in the oil and gas industry. The increasing demand for hydrocarbons is driving the exploration and production of reservoirs previously deemed uneconomical. The low-permeability limit for such reservoirs is continually being reduced while the limit for reservoir temperature is increasing. IPTT techniques address these trends by extending the limits for high-quality data acquisition.
The decision on whether to perform IPTT requires an estimate of permeability. This estimate usually comes from either pretesting or other well data such as nuclear magnetic resonance (NMR) logs. However, these measurements have a shallow depth of investigation and may underestimate the mobility of the reservoir fluids because of formation damage such as fines invasion, or high-viscosity fluid in the invaded zone. To displace invaded fluids in low-permeability formations can be challenging, usually requiring a high drawdown to pump the mud filtrate and fines from the formation. High-performance packers and pumps are essential in such environments that require a large number of high differential-pressure cycles.
In this paper three case studies of IPTT in low-permeability reservoirs in the North Sea are presented. In the first, pretesting with a single probe and dual-packer indicated a tight formation (no fluid communication between the tool and formation was established). IPTT was attempted and fluid moved at a drawdown of around 80 bar. The subsequent influx of formation gas reduced the drawdown significantly and a large increase in mobility was observed.
In the second tight gas case study gas influx was detected, but because of the large drawdown the gas compressibility prevented a large-volume cleanup and the test was aborted. This case shows the limit of what is achievable in this environment.
The third case study illustrates a very low-permeability limestone that was straddled with a dual-packer-standard-probe testing configuration. The downhole pump was equipped with a high-pressure displacement unit (DU). This pump configuration handled the high initial drawdown required to clean up the damaged zone. Initial cleanup pumping was followed by 30 hours of producing time and then a final pressure buildup. The result was a high-quality estimate of deep formation properties and fluid samples with very low contamination levels. A lesson learned was that formations considered "tight" according to data available before formation testing may be productive and capable of flowing hydrocarbons when evaluated with IPTT. Compared with the cost of a drillstem test (DST) in low permeability conditions, the dual-packer tool provided a fast, cost-efficient, and flexible way of testing individual zones.
Non-Retrievable Rotating Liner Drilling System Successfully Deployed to Overcome Challenging Highly Stressed Rubble Zone in a GOM Ultra-Deepwater Sub-Salt Application
Authors: Kunning Jim , Wu Yafei , Thomson Ian J. , Marshall Larry , Daigle Derrick , Mata Henry J. , Pena Robert , Hensgens Matt , Eppley Billy 
Published: October 2009

Abstract
Worldwide drilling and exploration activities offshore in deep and ultra-deep waters have increased significantly in the last few years. Many of the most attractive prospects are sub-salt or near-salt environments in the Gulf of Mexico (GoM), Brazil, and West Africa.
Operators are always looking for ways to reduce risks and maximize value in these extremely high-cost environments. Highly technical challenges include: drilling through depleted formations, lost circulation zones, weak formations, rubble zones, and tar/bitumen intervals. When encountered, these hazards lead to a significant increase in nonproductive time (NPT) and ultimately to significant financial losses.
This paper presents some of the geo-mechanical drilling hazards encountered in an ultra-deepwater well in the GoM Walker Ridge area, the impact of those hazards to the drilling operation, and the outcome of the deployment of a non-retrievable rotating liner drilling system. This drilling system, in conjunction with a specially designed liner drilling PDC bit, enabled operators to drill through and isolate a challenging highly stressed rubble zone found adjacent to a problematic tar/bitumen layer.
The result of this successful deployment and the high deepwater drilling operating costs show the tremendous potential to deliver value by providing a simple proven solution that saves drilling time and cost when in a hostile environment. Before running the liner drilling system, nonproductive activities accounted for a total of 26 days. These included attempts to overcome unexpected issues associated with a severe tar attack, and sidetracking the well, which represented millions of dollars in losses to the operator.
A successful liner drilling system solution was crucial, and it enabled the operator to finish the well and hit the proposed pay zone. Without the success of this operation, it is likely that an extra string of liner would have been required and that the operator's final objectives wouldn't have been achieved.
Casing and liner drilling has demonstrated to have the potential in a wide variety of other offshore areas where similar hazardous environments may be encountered.
Data, Information, Knowledge, Wisdom: Shaping E&P World
Authors: Lyadina-Saville E. 
Published: October 2009

AbstractModern measurement systems for E&P applications produce overwhelming amounts of raw data often facing limitations of storage, transmission, analysis, interpretation and decision making. Rational assessment of information content at each stage of measurement, processing and interpretation is necessary for optimization of data flow. Analysis of data evolution and its nature along the information pyramid becomes of primary importance in E&P applications.We performed an information-theoretical analysis of various types of data available in E&P applications, in their evolution from raw Data to Information to Knowledge to Wisdom as defined by Ackoff hierarchy (DIKW).Our analysis is applicable to broad range of E&P information systems for MWD, LWD, wireline and other tools.DIKW hierarchy is the way from ‘know nothing’ (data) to ‘know what’ (information) to ‘know how’ (understanding) to ‘know what is best’ (wisdom). This is the class of models for representing structural and functional relationships between data, information, knowledge, and wisdom, where the later is understood as ability to increase effectiveness and add value. Evaluated understanding (wisdom) is the only stage of DIKW evolution dealing with the future; this is the tool for decision making. We describe how such mathematical and computational techniques as data mining, data compression, filtering, pattern recognition, classification and clustering operate within DIKW information pyramid. In addition to classic Ackoff information model, we explore its various modifications, which include feedback loops. Such feedback from the stage of evaluated understanding (wisdom) to information stage is useful when solving inverse problems common in E&P applications. Evaluated understanding (wisdom) provides ‘what is best?’ answer acting as prior information for solving an inverse problem. We give examples of DKW evolution for various MWD, LWD, wireline data systems and Reservoir Management. These examples are based on publications stored in SPE e-library – the invaluable tool for information exchange between E&P professionals. Conclusion: Analysis of DIKW hierarchy is the effective tool for designing optimal measurement, processing and interpretation systems for oil and gas industry.
A Unified, Multidisciplinary Approach to the Planning and Design of Deepwater Waterflooding Projects
Authors: Chaban Fady R. , Sharma Mukul M. , Suri Ajay , Gibson Grant 
Published: October 2009

AbstractToday and in the future many of the deepwater projects in the Gulf of Mexico and elsewhere around the world will be producing under waterflooding conditions to increase hydrocarbon recovery and support reservoir pressure. The success of the water injection program is critical to the overall project economics. As such a clear methodology, workflow and attention to detail are needed in the planning, design and implementation of these projects.This paper presents an integrated and practical approach for implementation at the Front End Engineering Design (FEED) stage of a project to optimize the future field development strategy, injectors design, facilities planning, and to maximize the total value of the asset. The proposed method efficiently interconnect elements related to surface facilities, topsides process, subsea architecture, subsurface equipment, water quality, well completion, down-hole flow controls and target injection rates in a common context.The workflow consists of coordinating the diverse elements of design in the project: facilities design (pump requirements and water treatment options), topsides-subsea network flow design, injector, drilling and well planning, and critical data gathering. Results of the studies to be conducted will provide reliable estimates of well injectivity, fracture lengths under different injection scenarios, the impact of thermal stresses on injectivity and fracture growth, injector completion design, surface injection pressure requirement, and subsea-subsurface flow parameters. The development of a comprehensive model incorporating these elements subsequently allows the evaluation of the major factors that can impact the fracture length, bottom-hole and surface injection pressures based on: injection rate and temperature, water quality, reservoir pressure, Young's modulus, absolute and relative permeability to water, and rock thermal coefficient for diverse completions types. Ultimately, a robust design of the waterflooding project with long-term water injection is obtained.This methodology plays a crucial role guiding the planning, design, evaluation and development of the details and specifications for the water injection system. The output generated helps to improve overall field understanding, utilizing and linking valuable information and technologies that are available to the subsurface and topsides design teams. Likewise, this approach represents a tool to solve technical and business challenges associated with waterflood project design.
Changing Selection Concepts: True Optimization of Drill Bits with Latest Generation Rotary Steerable Systems
Authors: Barton Steve , Pierce Garrett , Stroud Daryl 
Published: October 2009

Abstract
Use of Rotary Steerable Systems (RSS) has steadily increased since their introduction in the mid-1990's. Improvements in durability, reliability, and operator familiarity, have moved these systems further into mainstream drilling use around the globe. However, the large majority of footage drilled with RSS is with side force (Push) tools. These tend to require some degree of sidecutting, thus utilize drill bits that have specifically engineered cutting structure, profile, and gauge design to achieve this. Due to common availability of this type of bit design, plus extensive experience with operators, they are often also utilized on the growing number of Point RSS. Due to the significant difference in operating mechanism, these bit designs can be poorly suited, resulting in sub-optimal drilling performance.
This paper describes a joint engineering approach in developing specific drill bits for the latest generation of RSS that utilizes point-the-bit technology. The project has included systematic testing at a purpose-built, full-size drilling test facility. This has enabled a direct comparison of the directional response, hole quality, and drill string vibration to be made for the various combinations of drill bit and RSS configurations tested. The testing and subsequent field performance has led to development of specified characteristics of the drill bit for optimal performance. To ensure consistent and accurate matching of the bit to this specific RSS, an interactive, intranet tool was developed. This software incorporates logic regarding tool operation and assesses these against key characteristics of the bit including length, profile, gauge geometry, cutting structure, and sidecutting capability. This allows the ideal design to be rapidly identified, particularly as some characteristics are not visible within the visual geometry of the bit.
Several case studies are documented that clearly demonstrate that the correct matching of drill bits to this specific Point RSS has delivered improved drilling efficiency with excellent directional control.
Solid Paraffin Inhibitor Pumped in a Hydraulic Fracture Provides Long-Term Paraffin Inhibition in Permian Basin Wells
Authors: Smith Tony , Szymczak Steve , Gupta D.V. Satya , Brown J. Mike 
Published: October 2009

Abstract
In a novel chemical technology development, a robust liquid paraffin inhibitor is adsorbed onto an inert solid matrix. This solid fits within the size distribution range of a 20/40 proppant. As a manufactured product, the solid composite holds sufficient paraffin inhibitor to provide more than one year of continuous paraffin inhibition in the subject wells.
Five wells have been treated since November 2007 by including a solid paraffin inhibitor composite with the proppant during a hydraulic fracture. These include rod-pumped and electric submersible pump (ESP) wells. The wells produce oil, gas and water and oil production have ranged between 50 – 300 BOPD (barrels of oil per day). The traditional treatment approach for paraffin inhibition for similar wells includes continuous downhole chemical injection, batch treatment with a paraffin inhibitors or paraffin inhibitor squeezes. For paraffinic wells that still precipitate paraffin despite chemical treatment, it is common to remove accumulated paraffin by circulating hot water or hot oil in the well.
To be effective and economic, a solid inhibitor composite must have two critical characteristics. First, it cannot adversely affect the fracturing fluid or proppant pack, thus calling for extensive fluid compatibility, crush and conductivity testing. Secondly, it must perform to inhibit paraffin deposition for a period of time deemed to be cost-effective. Chemical effectiveness is measured in the lab through comparative pour point tests, cold finger deposition tests and through field observation history, e.g. the ESP's pulled for maintenance reasons show no sign of paraffin deposition unlike untreated offset wells. To date, except for a problem due to the loss of power in the field the operator reports paraffin deposition-free production.
Operator lifting cost is a function of lease expenses and oil production. When a well fails due to paraffin deposition the operator incurs a cost of remediation and a loss of production. By placing an inhibitor in the fracture, the paraffin is inhibited in the formation, at the perfs and in the tubulars. The cost of the inhibitor is more than justified by the savings in operational costs and the value of continuous and increased oil production.
Low Pressure System for Gas Wells: Do We Need It? How Low Should We Go? A Compression Strategy for Tight Gas Wells in South Texas
Authors: Bui Quynhthy , Harms Larry , Munoz Efren , Becnel Joe 
Published: October 2009

Abstract
In a large field with thousands of wells of different ages and qualities, determining the optimum operating pressure is a challenging task. This study looks at the Lobo Field in South Texas which has approximately 1800 tight gas wells currently in production to determine the effect of pressures on recovery and the benefits vs. costs of compression. Wells were divided into 3 groups that share similar characteristics and modeled using the integrated production modeling tools to evaluate recovery vs. line pressure. Results show that the better wells can produce longer in a high pressure system before loading up and needing lower pressure, therefore, cost of compression per unit volume is lower. Wells with lower reserves do not stay in the intermediate pressure gathering system long before needing low pressure, thus for these wells the fuel savings from having an intermediate pressure system does not offset the cost. Well head compression is only attractive for the better wells.
Role of Failure Mode on Rock Cutting Dynamics
Authors: Block Gareth , Jin Howie 
Published: October 2009

Abstract
Rock cutting leads to a combination of brittle and ductile failure, and each failure mode has a different effect on drilling efficiency and the morphology of cuttings produced while drilling. A commercial, two-dimensional Discrete Element Method (DEM) code was used to investigate the link between cuttings morphology and downhole conditions using a single polycrystalline diamond compact (PDC) cutter. The methods described here differ significantly from previous studies in that grain-level forces were spatially averaged to determine the rate of energy dissipation within the rock volume during the entire cutting process. Stress-space methods and plasticity theory were then used to calculate the total energy lost due to brittle and ductile failure modes separately. Results indicate a direct and quantifiable relationship between confining stress, down-hole pressure, drilling efficiency and a transition from chip-like to ribbon-like cuttings morphologies.
Predicting Flow Profile of Horizontal Well by Downhole Pressure and DTS Data for Water-Drive Reservoir
Authors: Li Zhuoyi , Zhu Ding 
Published: October 2009

Abstract
Downhole pressure and temperature data are important information to help us understand the bottom-hole flow condition. The data today are readily available from permanent monitoring systems such as downhole gauges or fiber optic sensors. In previous study we have showed that using temperature and pressure data, water entry along a horizontal wellbore can be detected by a semi-analytical model. Flow in the wellbore is well-defined but flow in the reservoir is described by a single phase, one-dimensional model. The assumptions limited application of the model for mostly a single-phase condition
In this paper, we present an improved model that is more flexible. We use streamline simulation method to solve the flow problem in the reservoir for fast track of reservoir flow. We developed a transient, three-dimensional, multiphase reservoir thermal model to calculate reservoir temperature. We integrated the reservoir flow model and thermal model with a horizontal well temperature model to predict the pressure and temperature distribution in a horizontal well system. We apply the model to a synthetic example. The example is an infinite water-drive case. The results of simulation show that the temperature features in a horizontal well can successfully detect the location and amount of water breakthrough. Meanwhile, even the pressure trend does not reflect the water entrance as clear as temperature curve, its value of easily indentify the reservoir permeability distribution is very helpful in temperature calculation. We apply the model to a field case - a horizontal well in the Sincor Field for heavy oil production. The results showed that we can successfully identify where and how much water entering the horizontal well in this field example.
We use an inversion method to interpret the pressure and temperature data to obtain flow rate profile along horizontal wells. The inversion method is the traditional Markov Chain Monte Carlo (MCMC) method. This stochastic method searches the possible solution in the parameter space and use the Metropolis-Hastings algorithm to judge the acceptance. We discuss how to reduce the parameters to make the inversion method work more efficiently according to the downhole pressure and temperature data.
Acid Re-fracturing: Is it a Good Practice?
Authors: Pournik M. , Mahmoud M. , Nasr-El-Din H. A. 
Published: October 2009

AbstractThe success of acid fracturing depends on the conductivity created and retained under closure stress in addition to the length of conductive fracture. Majority of acid fracturing treatments show a sharp decline in conductivity with increasing closure stress with almost no significant conductivity after a short production time. As a result, many wells are re-fractured in order to restore back to the original productivity after the initial fracture. However, the success of these re-fracture treatments has been diverse with respect to extent of stimulation. The effect of re-fracturing on acid fractured wells has not been studied and the conditions that result in success or failure of re-fracturing operations are not understood.An experimental study was conducted to investigate the effect of re-fracturing on already acid fractured cores exposed to closure stress. Indiana limestone cores were acidized with a typical acid system of 15 wt% HCl acid viscosified with a polymer under typical field conditions. After the first acidizing process, conductivity measurements were conducted on acid-etched core faces up to a certain closure stress. While the fracture was kept under the closure stress, a re-fracturing treatment was conducted under the same conditions as the initial acidizing. The re-etched fractures were once again placed under different levels of closure stress and conductivity measurements taken at each stress. Experiments were conducted under different conditions of leak-off, polymer concentration and closure stress after the first acidizing in order to determine influence of these parameters on the re-fracturing conductivity.Acid re-fracturing enhanced fracture face etching, while significantly increased fracture conductivity under closure stress. However, leak-off, polymer concentration, and closure stress did influence the degree of success of acid re-fracturing. The refractured sample with leak-off and lower polymer concentration resulted in the most enhanced fracture conductivity in comparison to the initial acid fracturing process.