Potential Sweet Spots Research Articles

Seismic-electromagnetic projection attribute: Application in integrating seismic quantitative interpretation and 3D controlled-source electromagnetic-magnetotelluric broadband data inversion for robust ranking and sweet spotting of hydrocarbon prospects in offshore northwest Borneo

We introduce a new seismic-electromagnetic (EM) projection (SEMP) attribute to improve the characterization of pay sands by integrating seismic P impedance and S impedance with electrical resistivity measurements leveraging on the high sensitivity of resistivity to fluid saturation and the capability of seismic data to delineate thin beds. Porosity is predicted using an extended elastic impedance (EEI) approach to reduce the risk of encountering SEMP anomalies related to low porosity. First, we determine the seismic-EM integration concept using well logs from a well that encountered hydrocarbons in a deepwater fold belt in offshore Borneo. The SEMP logs supported by the EEI log successfully delineate the pay zones in the well. Second, we extend the approach in three dimensions and evaluate its effectiveness using large-size seismic controlled-source EM (CSEM) and magnetotelluric (MT) data from the same area. The seismic data are inverted to produce P- and S-impedance volumes. EEI volume calibrated to total porosity also is produced. We then perform 3D anisotropic cross-gradient joint CSEM and MT inversion of a large-size survey comprising 647 receivers with receiver spacing of 1.5–3 km at prospect to regional scale. The SEMP volumes computed using the seismic and CSEM-MT inversion results are then interpreted with the EEI volume to identify possible geobodies of pay sand. Resistive geobodies with low porosity are assigned higher risks because they are likely due to compaction rather than hydrocarbon presence, whereas geobodies with high porosity are assigned lower risks and identified as potential sweet spots. The geobodies need to be corroborated with independent geologic studies to mature them into exploration prospects and assess their associated risk and potential. Although a vertical transverse isotropy approximation is used in our CSEM-MT study, the SEMP concept also is applicable to cases considering tilted transverse isotropy or arbitrary anisotropy where available and operational for such large-size exploration data.

Garau Formation as an unconventional hydrocarbon resource in southwestern Iran: a geochemical investigation

Due to the growing need for hydrocarbons and the limited conventional resources, paying attention to unconventional oil and gas resources is essential. The upper Jurassic-Lower Cretaceous in western and southwestern Iran contains the most crucial source rocks of the Zagros sedimentary basin. One of the richest source rocks is the shaly Garau Formation. Owing to geochemical and geological characteristics, the Garau Formation, with Neocomian to Coniacian age and periodicity of radiolore black limestones with black pyrite bituminous shales, ammonite, and chertite shale, is the suitable potential sweet spot as oil shale and gas shale. In this study, a comprehensive regional study was conducted on the entire Garau Formation basin using Rock–Eval parameters and organic matter maturity data. In addition to investigating the hydrocarbon generation potential of the Garau Formation as a source rock, the prospect of this Formation as oil and gas shales in the entire Garau basin was investigated. For this purpose, 31 fields in 5 important sub-basins of Zagros, including East Lorestan, West Lorestan, Izeh zone, Dezful Embayment, and Abadan plain were investigated. The study showed that total organic carbon varies between 0.17 and 24.6, and more than 75% of total organic carbon had values greater than 1. By examining the quantity, quality, and maturity parameters and considering the necessary thresholds, it was found that East Lorestan and West Lorestan have the conditions for oil and gas shales. The highest quantity and best quality of organic matter are related to Eastern Lorestan. By moving west and south of Garau Basin, the quantity and quality of organic matter decrease, and the hydrogen index proves the results. Vitrinite reflection studies indicated that the lowest and highest levels of organic matter maturity belong to East Lorestan and West Lorestan, respectively. Therefore, the northeast of Garau Basin (Eastern Lorestan) has the potential for oil shale, and the northwest of the Basin (Western Lorestan) has the potential for gas shale.

Silurian hot shale occurrence and distribution, organofacies, thermal maturation, and petroleum generation in Ghadames Basin, North Africa

The Silurian hot shale in one of the African superglobal petroliferous sedimentary basins (Ghadames) were studied to provide new regional insights regarding the organofacies type, occurrence and distribution, thermal maturation levels, and the timing of petroleum generation and expulsion. Based on regional integrated geochemical data such as Rock-Eval and Leco TOC, the evaluation of hot shale organofacies was carried out to characterize the type, occurrence and distribution and to obtain present-day regional maps of total organic carbon content (%TOCpd), hydrogen index (HIpd) and kerogen transformation (TRpd). The hot shale thermal maturation levels were obtained using pyrolysis Rock-Eval Tmax, equivalent vitrinite reflectance (%VRo), and one, two and three-dimensional calibrated basin modeling approaches. Results show that the hot shale was entirely dominated by typical marine organofacies type B (kerogen type I/II) with %TOC ranging from 2% to 17.5%, and hydrogen index ranged from 50 to 750 mg HC/g TOC with apparent systematic trends throughout the basin margins, and depocenter for both %TOC and HI. The hot shale thermal maturation study indicates a general maturation range from early to the post-mature stages with 0.45–2.45 %VRo and 380 °C–510 °C as pyrolysis temperature range. The one and two-dimensional kerogen transformation study based on the obtained refined thermal model shows a general range from 20% to 98% transformation levels with a systematic increase from the basin margins toward the basin depocenter. The hot shale oil window (top and bottom) is defined to be in the range of 1,400 m–4,000 m burial depth, while the dry gas window of the hot shale is presented at a burial range of 4,000 m–5200 m. Such an observation and current geological and geochemical conditions rank the hot to be an attractive potential sweet spot area as an unconventional shale oil/gas play target in Ghadames Basin for future exploration activity in western Libya, eastern Algeria, and southern Tunisia.

Sweet spots prediction through fracture genesis using multi-scale geological and geophysical data in the karst reservoirs of Cambrian Longwangmiao Carbonate Formation, Moxi-Gaoshiti area in Sichuan Basin, South China

AbstractFractures play a vital role in reservoir transformation, but the distribution of faults and fractures is difficult to obtain by observing cores, which ultimately limits the effective development of gas dolomite reservoirs. We propose an integrated method that incorporates thin-section observations, three-dimensional (3D) seismic data, and image logs to interpret the distribution of faults and fractures of Cambrian Longwangmiao Carbonate Formation to predict potential development areas in the Moxi-Gaoshiti area of the Sichuan Basin, South China. Firstly, the faults were well interpreted by using the automatic tracking and 3D visualization technique based on the new seismic combination attribute of symmetry and ant tracking. Secondly, a comprehensive analysis was conducted using the thin sections, paleogeomorphology, and in situ test results to determine the fracture types (corrosion and structural fractures). The results help us to find potential sweet spot zones with good permeabilities, which is of great significance in reducing the risk of water production of drilled wells in the field development.

Coalbed Methane Potential Evaluation and Development Sweet Spot Prediction Based on the Analysis of Development Geological Conditions in Yangjiapo Block, Eastern Ordos Basin, China

The evaluation and prediction of favorable coalbed methane (CBM) sweet spot play an important role in well location deployment and recovery prediction in CBM blocks. This work investigates the CBM geology and accumulation characteristics of No. ( 8 + 9 ) coal in the Carboniferous Taiyuan Formation in Yangjiapo block based on data from 14 CBM wells. The desorption index is proposed to be used to study the CBM desorption potential in Yangjiapo block, and the parameter of reduced water level is adopted to study the CBM hydrodynamics of the block. Furthermore, the analytical hierarchy fuzzy evaluation method is used to evaluate and prediction the CBM development sweet spot in Yangjiapo block. The results show that the buried depth of the No. ( 8 + 9 ) coal seam in Yangjiapo block varies from 693.20 to 1213.20 m, the coal thickness is from 5.40 to 13.10 m, the gas content is from 5.89 to 10.55 m3/t, and the minimum horizontal principal stress is from 9.80 to 20.82 MPa. The desorption potential is better in the southeastern and central-western part of the block. It is found that there is a positive relationship between CBM content and hydrodynamics and indicated that CBM easily concentrates in the lower reduced water level area. The CBM favorable development sweet spot is forecasted to be located in the southeastern part, central-western region, and northeastern part of Yangjiapo block.

Rock physics-driven quantitative seismic reservoir characterization of a tight gas reservoir: a case study from the Lower Indus Basin in Pakistan

Abstract The Lower Goru (LG) sandstone formation of Cretaceous age is a widely distributed proven hydrocarbon producing reservoir in the Lower Indus Basin, Pakistan. The tight early Cretaceous LG massive-sand (MAS) sandstone unit has low porosity and low permeability, which makes lithologies and litho-facies discrimination difficult. Based on a rock physics-driven quantitative seismic reservoir characterization approach, we accurately predict lithology and fluid saturations defined through litho-facies image mapping for the MAS sandstone reservoir unit. The workflow starts by preparing data for consistent petrophysical interpretation and rock physics analysis. Rock physics modelling generates a consistent set of elastic logs and establishes the link between reservoir properties and seismic amplitudes via elastic properties. Fluid substitution analysis indicates that gas sand separation from seismic data is difficult to achieve by conventional inversion methods due to very low porosity and stiffness of the rock frame which exhibits an AVO class I response. Therefore, we employed a novel joint impedance and facies inversion (Ji-Fi®) technology and jointly inverted for acoustic impedance and seismic litho-facies images. Ji-Fi produced a significantly better facies (gas sand) image and identified a potential sweet spot for a future appraisal and development well location.

Noisy 4D seismic data interpretation: Case study of a Brazilian carbonate reservoir

A legacy seismic data set from 2001 and 2011 was used for time-lapse interpretation over a Brazilian carbonate reservoir in Field-X of Campos Basin. The acquired 4D seismic data set was noisy and initially deemed to be uninterpretable. Pressure data were limited, and the initial simulation model was poorly calibrated. All of these challenges warranted the need to establish an interdisciplinary interpretation workflow. In this paper, we introduce a tiered integrated approach to optimize data value from multiple sources. The results of interwell connectivity from production data analysis were used as a basis for assignment of 4D signal confidence flags, which were later combined with simulation-to-seismic modeling of history-matched realizations, enabling interpretation efforts of the noisy 4D seismic data set. This integrated approach led to identification of the injected water front and a potential sweet spot for an infill well.

An approach to explore for a sweet spot in randomized trials

ObjectiveThe objective of the study was to demonstrate how a conventional randomized trial can be analyzed through a stratified or a matched approach to identify a potential sweet spot where observed differences might be accentuated in the mid range of disease severity. Design and SettingWe review a landmark randomized trial of heart failure patients that tested whether implantable defibrillators reduce mortality (n = 2,521). ResultsOverall, 22% (182/829) of the patients in the defibrillator group died compared with 29% (484/1,692) of patients in the control group. Proportional hazards analysis yielded a modest 25% survival benefit (hazard ratio = 0.75, 95% confidence interval: 0.63 to 0.89). Stratified analysis of the trial yielded a larger 52% survival benefit for those in the middle quintile of disease severity (hazard ratio = 0.48, 95% confidence interval: 0.29 to 0.79). In contrast, little of the survival benefit was explained by patients with the greatest disease severity (hazard ratio = 0.89, 95% confidence interval: 0.69 to 1.15). The discrepancy between crude and stratified analyses could be visualized by graphical displays and replicated with matched comparisons. ConclusionOur approach for analyzing a randomized trial could help identify a potential sweet spot of an accentuated treatment effect.

Origin of deep-water fine-grained sediments as revealed from the Lower Cretaceous rifting basin sequence in the Lingshan Island, Yellow Sea, Eastern China

Understanding the sediment dynamics responsible for the deposition of fine-grained sediments is essential for studying fine-grained sediment origin and its distribution, which is of a great significance for unconventional oil and gas exploration and development. Fine-grained sediments from a Lower Cretaceous rift-basin sequence in the Lingshan Island, the middle of the Dengta section in the Lingshandao Formation were studied. On the basis of detailed outcrop investigation, thin section observation, and laboratory measurements, seven types of lithofacies and three lithofacies associations were identified in the fine-grained sediment sequence. The sediment dynamics were deduced from a comprehensive examination and interpretcation of the sedimentary structures and lithofacies associations. The fine-grained sediments in the research area belong to a silt dominated subclass, which is composed mainly of thin-bedded siltstones with normal grading and mudstones with horizontal lamination. Suspension settling is responsible for the development of horizontal lamination in some mudstone. The Bouma-like lithofacies associations are developed by downslope fine-grained turbidity currents. The hybrid event bed-like lithofacies associations are formed by hybrid flow, while turbidity currents transformed to muddy debris flows downslope. The interbedded thin sandstone and mudstone banded lithofacies associations may be resulted from a downslope transitional flow between a turbidity current and a muddy debris flow. The vertical facies stacking patterns of the fine-grained sediment sequence indicatec that the fine-grained gravity flow may have been evolved from a transitional flow to a debris flow then to a low-density turbidity flow and finally to a hybrid flow. Lithofacies associations deposited by hybrid flow and transitional flow are potential sweet spots for unconventional oil and gas exploration in such fine-grained sediment formation.

Using Multiazimuth Seismic Data for Anisotropy Estimation in an Unconventional Reservoir

Productivity of a well in an unconventional reservoir is governed by various static and dynamic reservoir characteristics. Many of these characteristics have proxies among pre and post stack seismic attributes that can be derived from Multiazimuth 3D Seismic Data. The task of a geoscientist in this kind of reservoir is to understand these proxies to predict production behaviour. Natural fracture density and azimuth, as well as horizontal stress azimuth are the key attributes that seismic can help predict. Seismic Velocity and Amplitude variations with azimuth can be used to predict fracture strike, relative fracture density and define potential structural sweet spots. Azimuthal data from a Multiazimuth 3D seismic survey in the Nappamerri Trough of Cooper Basin has been interpreted to estimate fracture intensity and orientation. Co-rendered structural maps are used to create stress maps for different interval of interest. Stress maps help to identify areas of higher anisotropy and areas of lower minimum horizontal stress and so facilitate optimised well placement. To test the geological significance of these maps, correlation of stress vectors against well Image log and cross dipole sonic data was completed. This ground truth validates the prediction of direction and distribution of reservoir fractures based on full azimuth seismic data in this area.

Advanced surface logging technology for unconventional plays: well-site applications in tight reservoirs

Advanced surface logging technology for unconventional plays: well-site applications in tight reservoirs

Applying of the Artificial Neural Networks (ANN) to Identify and Characterize Sweet Spots in Shale Gas Formations

The main goal of the study was to enhance and improve information about the Ordovician and Silurian gas-saturated shale formations. Author focused on: firstly, identification of the shale gas formations, especially the sweet spots horizons, secondly, classification and thirdly, the accurate characterization of divisional intervals. Data set comprised of standard well logs from the selected well. Shale formations are represented mainly by claystones, siltstones, and mudstones. The formations are also partially rich in organic matter. During the calculations, information about lithology of stratigraphy weren’t taken into account. In the analysis, selforganizing neural network – Kohonen Algorithm (ANN) was used for sweet spots identification. Different networks and different software were tested and the best network was used for application and interpretation. As a results of Kohonen networks, groups corresponding to the gas-bearing intervals were found. The analysis showed diversification between gas-bearing formations and surrounding beds. It is also shown that internal diversification in sweet spots is present. Kohonen algorithm was also used for geological interpretation of well log data and electrofacies prediction. Reliable characteristic into groups shows that Ja Mb and Sa Fm which are usually treated as potential sweet spots only partially have good reservoir conditions. It is concluded that ANN appears to be useful and quick tool for preliminary classification of members and sweet spots identification.

Tax motivated derivative structures with 'sweet spot' payoffs

In this paper, we review the role of market microstructure issues in the design and function of tax shelter schemes based on exotic currency option transactions. We review instruments commonly used in the currency derivative markets and discuss the critical role of market frictions in evaluating the sensibility of transactions from an economic perspective. We analyse a sample transaction with a potential 'sweet spot' payoff in order to identify the role of the potential sweet spot payoff in the valuation of the structure. We estimate the fundamental value of the structure using a theoretical value for the sweet spot. We then explain that realistic consideration of market microstructure, or trading frictions, suggest that the actual value claim for a potential sweet spot payoff is zero. Our analysis provides a simple framework for determination of the reasonableness of a claimed profit motive as motivation for entering into structured transactions that contain currency derivatives.

Tax motivated derivative structures with 'sweet spot' payoffs

In this paper, we review the role of market microstructure issues in the design and function of tax shelter schemes based on exotic currency option transactions. We review instruments commonly used in the currency derivative markets and discuss the critical role of market frictions in evaluating the sensibility of transactions from an economic perspective. We analyse a sample transaction with a potential 'sweet spot' payoff in order to identify the role of the potential sweet spot payoff in the valuation of the structure. We estimate the fundamental value of the structure using a theoretical value for the sweet spot. We then explain that realistic consideration of market microstructure, or trading frictions, suggest that the actual value claim for a potential sweet spot payoff is zero. Our analysis provides a simple framework for determination of the reasonableness of a claimed profit motive as motivation for entering into structured transactions that contain currency derivatives.

Applying Lessons Learned To Minimize Overall Investment in Unconventional Plays

This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper SPE 172973, USD 40 Billion Learning Curve: Leveraging Lessons Learned To Minimize the Overall Investment in Unconventional Plays,by C.N. Fredd, SPE, J.L. Daniels, SPE, and J.D. Baihly, SPE, Schlumberger, prepared for the 2015 SPE Middle East Unconventional Resources Conference and Exhibition, Muscat, Oman, 26 - 28 January. The paper has not been peer reviewed. The development of unconventional resources in North America was aided by the readily available infrastructure, water resources, expertise, and a general understanding of potential sweet spots caused by numerous well penetrations. Even with these favorable conditions, an estimated 40% of unconventional wells are uneconomical. This paper provides a retrospective assessment of the Barnett and Eagle Ford Shale plays to highlight lessons learned and the associated value of those learnings. Introduction Although horizontal drilling and multistage fracturing (MSF) have changed the economic viability of unconventional resources significantly, such drilling has also encountered a wide range of production variability. This nonideal production performance further leads to consumption of local resources such as water and proppant that are used in hydraulic-fracturing treatments. The poor economic performance of a high percentage of wells is the result of spatial variability in reservoir characteristics such as hydrocarbon in place, gas/oil ratio (GOR), and reservoir pressure; lateral heterogeneity along the wellbores; limited accuracy of well placement; and variability in drilling, completion, and stimulation practices. The development of best practices and the learning curves associated with the Barnett and Eagle Ford Shale plays are detailed in the complete paper, as are the rationale and methodology for retrospective assessments of both plays. Barnett Shale Retrospective Assessment The retrospective assessment for the Barnett was simulated for five specified cases by use of the parameters summarized in Table 1 and the corresponding cost parameters summarized in Table 4 of the complete paper. This cost model was used to represent the average cost throughout the development. Hence, this retrospective assessment does not account for the actual variability in cost from year to year.

Probabilistic lithofacies prediction from prestack seismic data in a heterogeneous carbonate reservoir

We mapped probabilities of lithology and fluid based on seismic and well observations in a heterogeneous carbonate reservoir of the Sichuan Basin, southwest China, thus characterizing the reservoir complexity and identifying the potential sweet spot. Rock physical analysis showed that the presence of a vuggy-fracture porosity system combined with the fluids’ effect complicate the elastic responses of heterogeneous carbonates. This also gives physical insight into how the elastic properties of different lithofluid classes can be distinguished. With the application of Bayesian linearized amplitude variation with offset inversion, we found that the posterior distribution of P- and S-wave velocities were reliably extracted, whereas the inverted density tended to show high uncertainty due to a lack of wide angle data in the migrated seismic gathers. Finally, a Bayesian approach was implemented to propagate uncertainty from prestack seismic data to lithofluid classes in an integrated framework. The gas-carbonate predictions with high posterior probabilities were consistent with well observations at the well location and the present geological continuity. The probability distributions for the anhydrite, limestone, and dolostone were essential to understand the reservoir architecture and delineate the reservoir heterogeneities. We also ascertained that the uncertainty of lithofacies prediction is determined by the uncertainty of seismic inversion as well as the uncertainty of the link between lithofacies to their corresponding elastic responses.

The effect of present day in situ stresses and paleo-stresses on locating sweet spots in unconventional reservoirs, a case study from Moomba-Big Lake fields, Cooper Basin, South Australia

The effect of stresses on permeability is a combination of external stress and pore pressure. We are examining if and how present-day in situ stresses and the spatial distribution of permeable domains in the Moomba-Big Lake fields in the Cooper Basin are correlated. We analysed image logs, well logs, and formation tests and calculated the orientation and magnitudes of the three principal stresses. A 3-dimensional model was constructed and the calculated stress magnitudes and orientations were applied to the model. The resulting stress distribution under the current day stress state showed a highly permeable domain indicating a sweet spot in the Big Lake field. This is currently the location of a gas pool that forms, with the Moomba field, one-third of the gas reserve in SA. No potential sweet spots are located in the Moomba area according to the stress model. We also used the finite element method (FEM) and the boundary element method (BEM) for modelling the behaviour of folds, fractures, and faults that formed during the tectonic history of the basin. We used geomechanical restoration techniques for locating sweet spots in the Moomba-Big Lake fields. The methodology attempts to reconstruct the current day structural and geometrical placement and predicts fractures generated due to stresses released during past tectonic events. Orientation of predicted fractures using FEM-based geomechanical restoration correlated well with the orientation of the image log fractures. The spatial distribution of paleo-stresses applied on the predicted fractures showed a potentially stressed fracture set in the location of the currently producing Big Lake sweet spot. However, orientation of predicted fractures using BEM-based geomechanical restoration correlated well next to the Big Lake fault but did not show any correlation away from the major fault. This is due to the fact that BEM restoration takes in consideration fault dislocation as the only driver of fracture generation and ignores the other factors. However, paleo-stress distribution using BEM restoration predicted the same producing area but with less accuracy due to the fundamentals of the BEM. No fracture density information can be extracted from any of the methods as the methodologies generate fractures with density that depends on the initial project mesh size. Accordingly, these methodologies can be used for locating the current-day and paleo-stresses, as well as fracture orientation but not density. Also, reservoir permeability is proved in this study to be controlled by a combination of current day and stored paleo-stresses.

Present-day in-situ stresses versus paleo-stresses for locating sweet spots in unconventional reservoirs

The effect of stresses on permeability is a combination of external stress and pore pressure. The authors examine if and how present-day in-situ stresses and the spatial distribution of permeable locations in the Moomba-Big Lake fields in the Cooper Basin are correlated. Image logs, well logs, and formation tests are analysed and the orientation and magnitudes of the three principal stresses are calculated. A 3D model was constructed and the calculated stress magnitudes and orientations were applied to the model using the software Poly3D. The resulting stress distribution in the present-day stress state showed a potential sweet spot in the Big Lake field, which is presently the location of a gas pool that forms, with the Moomba field, one-third of the gas reserve in SA. No potential sweet spots, however, are located in the Moomba area. The authors also used the finite element method (FEM) and the boundary element method (BEM) for modelling the behaviour of folds, fractures, and faults and for mimicking the tectonic history of the basin. Software codes Dynel3D and Traptester were used to examine the validity of geomechanical restoration techniques for locating sweet spots in the Moomba-Big Lake fields. The methodology attempts to reconstruct the present-day structural and geometrical placement and to predict fractures generated due to stresses released during past tectonic events. Predicted stresses succeeded in mapping the same sweet spot in the Big Lake field using both software codes. Accordingly, the present permeability and production rate is controlled by a combination of present-day and stored stresses.

Observing fracture lineaments with Euler curvature

In the last several years, seismic-curvature attributes have been shown to be very useful in delineation of folds, flexures, and faults. Although many curvature measures have been introduced, the most-positive and most-negative principal curvatures (k1 and k2) are found to be the most useful. All other curvature measures can be derived from the two principal curvatures. For example, the components of apparent curvature projected parallel to the dip azimuth and strike of a dipping plane are useful in given tectonic and stress settings. Euler curvature is a generalization of the dip and strike components of curvature in any user-defined direction, as applied to the interpretation of surface-seismic data. This attribute is useful for interpretation of lineament features in desired azimuthal directions, for example, perpendicular to the minimum horizontal stress. If a given azimuth is known or hypothesized to be correlated with open fractures or if a given azimuth can be correlated with enhanced production or effective horizontal drilling, a Euler-curvature intensity volume can be generated for that azimuth, thereby high-grading potential sweet spots.

The ant and the grasshopper

Pointer information is a prerequisite for most program analyses, and the quality of this information can greatly affect their precision and performance. Inclusion-based (i.e. Andersen-style) pointer analysis is an important point in the space of pointer analyses, offering a potential sweet-spot in the trade-off between precision and performance. However, current techniques for inclusion-based pointer analysis can have difficulties delivering on this potential. We introduce and evaluate two novel techniques for inclusion-based pointer analysis---one lazy, one eager 1 ---that significantly improve upon the current state-of-the-art without impacting precision. These techniques focus on the problem of online cycle detection, a critical optimization for scaling such analyses. Using a suite of six open-source C programs, which range in size from 169K to 2.17M LOC, we compare our techniques against the three best inclusion-based analyses--described by Heintze and Tardieu [11], by Pearce et al. [21], and by Berndl et al. [4]. The combination of our two techniques results in an algorithm which is on average 3.2 xfaster than Heintze and Tardieu's algorithm, 6.4 xfaster than Pearce et al.'s algorithm, and 20.6 faster than Berndl et al.'s algorithm. We also investigate the use of different data structures to represent points-to sets, examining the impact on both performance and memory consumption. We compare a sparse-bitmap implementation used in the GCC compiler with a BDD-based implementation, and we find that the BDD implementation is on average 2x slower than using sparse bitmaps but uses 5.5x less memory.