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Washington, DC, United States
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Guk V.,IHS Global | Tuzovskiy M.,Irkutsk Oil Company | Wolcott D.,Irkutsk Oil Company
Proceedings - SPE Annual Technical Conference and Exhibition | Year: 2015

Numerous papers have been published in recent years on the subject of optimization of multiple transverse fractures in horizontal wells (for instance Saputelli et al., 2014). These studies usually focus on searching for an economical optimum based on multiple runs of 3D or 2D numerical simulator, each for certain fixed properties of hydraulic fractures. What we found missing is a systemized approach to calculate a solution to this problem. The objective of this study is to develop a systemized, rigorous mathematical and unified approach to the design of multiple transverse fractures in horizontal well - an extension of Unified Fracture Design (UFD). This paper provides a rigorous methodology to optimize the number of fractures (and consequently, fracture geometry) for a given amount of proppant. We follow the UFD concepts and solve our problem in dimensionless variables. For the case of multiple fractures these are: Proppant Number (NP), Penetration Ratio (Ix), Dimensionless Conductivity (CfD) and Aspect Ratio (yeD) for each fracture, which is inversely proportional to the number of fractures. We used the Direct Boundary Element method to generate the Dimensionless Productivity Index (JD) for a given range of these parameters (28,000 runs) for the Pseudo-Steady state case. Finally we plot total JD as a function of the number of fractures for various NP, which allows optimization. In addition, we generate minimum width curves for various proppants, which represent a practical constraint. Based on our study we found the following: 1. For a given volume or proppant, NP, total JD for multiple fractures increases to an asymptote as the number of fractures increases. This asymptote represents a technical potential for multiple fractures and for high Proppant Numbers (NP ≥ 100) reaches a technical potential of 3/πNp. 2. Below this asymptote, the more fractures that are created for a fixed NP the larger the JD 3. In practice however, there's a minimum fracture width (3 proppant grains), which constrains the fracture geometry and therefore maximum JD. It was shown, that for the case when 20/40 sand is used for multiple hydraulic fracturing of 0.01md formation with square total area, optimal number of factures reduces to approximately Np/25. 4. Application of horizontal drilling technology with multiple fractures assumes availability of high Proppant Numbers. We show mathematically that the alternative low Proppant Numbers (NP ≤ 20 for the case in p.3) are impractical for multiple fractures because total JD cannot be significantly higher than JD for optimized single fracture in the same area. In practice this means low formation permeability and/or high proppant volumes are necessary for multiple fracture treatments. Our work shows the methodology to determine optimum geometry and required volume to perform multifracture treatments. 5. Total proppant mass (and hence, NP) used for the fracture design must be selected based on economic considerations. For this purpose we constructed a relationship between total JD and the NP, which accounts for the minimum fracture width requirement. Our paper presents a mathematically rigorous, systematic and comprehensive approach to the selection of optimal number of transverse hydraulic fractures in a horizontal well. Using the relationship between Proppant Number and maximum practical JD, the proppant mass should be selected for the treatment. Then, based on the formation and proppant permeability, the maximum number of fractures should be calculated for a given NP using the generated type curves and minimum width restriction. © Copyright 2015, Society of Petroleum Engineers.

Yang W.,Lewin Group | Dall T.M.,IHS Global | Zhang Y.,MedImmune | Zhang S.,Booz Allen Hamiltons Advanced Analytics Division | And 3 more authors.
Health Affairs | Year: 2012

Despite the documented benefits of quitting smoking, studies have found that smokers who quit may have higher lifetime medical costs, in part because of increased risk for medical conditions, such as type 2 diabetes, brought on by associated weight gain. Using a simulation model and data on 612,332 adult smokers in the US Department of Defense's TRICARE Prime health plan in 2008, we estimated that cessation accompanied by weight gain would increase average life expectancy by 3.7 years, and that the average lifetime reduction in medical expenditures from improved health (\$5,600) would be offset by additional expenditures resulting from prolonged life (\$7,300). Results varied by age and sex: For females ages 18-44 at time of cessation, there would be net savings of \$1,200 despite additional medical expenditures from prolonged life. Avoidance of weight gain after quitting smoking would increase average life expectancy by four additional months and reduce mean extra spending resulting from prolonged life by \$700. Overall, the average net lifetime health care cost increase of \$1,700 or less per ex-smoker would be modest and, for employed people, more than offset by even one year's worth of productivity gains. These results boost the case for smoking cessation programs in the military in particular, along with not selling cigarettes in commissaries or at reduced prices. © 2012 Project HOPE- The People-to-People Health Foundation, Inc.

Roelofsen J.,IHS Global | Chungkham P.,IHS Global | Parry J.,IHS CERA
73rd European Association of Geoscientists and Engineers Conference and Exhibition 2011: Unconventional Resources and the Role of Technology. Incorporating SPE EUROPEC 2011 | Year: 2011

Exploration for Unconventional Gas in Europe has well started. Some 200,000 square kilometers in western and northern Europe have been contracted for unconventional gas exploration, which amounts to 13 percent of the total onshore licensed acreage. The first exploration wells to evaluate shale gas potential have been drilled and several coal gas pilot projects are underway. IHS-CERA has conducted a study to analyze 35 shale gas and 19 coal gas (CBM) plays. The total GIP (Gas-In-Place) has been estimated at more than 5,500 Tcf (trillion cubic feet or 157 trillion cubic meters) for shale gas and at approximately 500 Tcf (14 Tcm) for coal gas. However, recovery from unconventional reservoirs is far less than the established recovery rates from conventional reservoirs and total recoverable gas is more likely in the 500-600 Bcf (billion cubic feet) range (unrisked reserves). This presentation described the methodology of research and a summary of the results of the study.

Dobrova H.,IHS Global | Gawenda P.,IHS Global | Ruchonnet C.,IHS Global | Renevey P.,IHS Global
73rd European Association of Geoscientists and Engineers Conference and Exhibition 2011: Unconventional Resources and the Role of Technology. Incorporating SPE EUROPEC 2011 | Year: 2011

The emergence of hydrocarbon production from unconventional reservoirs in the US has spawned high hopes of similar results in Continental Europe. Recently, a true pursuit to acquire acreage for exploration of unconventional resources has been undertaken by companies of all sizes, from supermajors to small players, often securing significant acreage positions. As a result, little unlicensed prospective areas remained available by end-2010. Presently, the main players on Europe's unconventional scene are the US majors ExxonMobil, Chevron, ConocoPhillips and Marathon Oil, followed by Eni, Talisman Oil, BNK Petroleum, Composite Energy, Lane Energy, San Leon and Toreador. Other companies, like Total, have pending applications, or are evaluating the resources (e.g. OMV). Several companies are bringing hands-on experience from the US shale gas operations. Field activities to assess shale gas/CBM potential have started in several European countries, including France, Germany, Italy, Poland, Sweden and the UK, and the level of operations is on the rise. Data amassed from the new operations will provide a better understanding of the geological and technical constraints of the hydrocarbon systems, testing also Europe's regulatory and economic conditions. They will provide tangible estimates of the prospective resources, reason for much speculation so far.

Roelofsen J.,IHS Global
73rd European Association of Geoscientists and Engineers Conference and Exhibition 2011: Unconventional Resources and the Role of Technology. Incorporating SPE EUROPEC 2011 | Year: 2011

Different resource classifications for the petroleum and mining industry have been in place for a long time. Attempts have been undertaken since more than thirty years to reconcile the various classifications into one over-reaching system. Reserves growth by new technology, changing reporting standards for the financial markets, supply security concerns and new resources like unconventional energy have urged for a better understanding of the global resource base. The United Nations Framework Classification (UNFC-2009) was established in 2009 to reconcile different classifications into one coherent system for various branches in the energy and mineral industry. This paper discusses the principles of this framework and its application for new energy sources like unconventional oil and gas.