Slowness‐frequency‐projection logs: A QC for accurate slowness estimation and formation property identification

Plona, Thomas J.; Endo, Takeshi; Wielemaker, Erik; Walsh, John J.; Yamamoto, Hiroaki

doi:10.1190/1.2370227

Cited by 4 publications

(1 citation statement)

References 5 publications

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“…Representative matrix porosities of reservoir layers are obtained. 9,10 Determination of fluids volume/fraction, distribution and identification Nuclear magnetic resonance techniques provide answers allowing differentiation of moveable and irreducible (nonmoveable) fluids; these results are integrated in petrophysics evaluation workflow for better assessment of reservoir production potential. Subdivision/classification of porosity distribution by means of several cut-offs on transversal relaxation time scale (as function of pore dimensions) is used for study and classification-comparison of porous media.…”

Section: -Sonicmentioning

confidence: 99%

Optimum Logging Programs in Tight Sands

Tchambaz

2009

EUROPEC/EAGE Conference and Exhibition

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High potential of tight sands (quartzitic sandstones) makes these non-conventional reservoirs a priority for oil companies during next decades. Due to numerous formation evaluation challenges in tight sands, conventional logging does not allow reliable and comprehensive investigations that are essential for exploration and development. Classical logging techniques/measurements are frequently affected by significant uncertainties, leading sometimes to erroneous evaluation results. New technology has brought advanced logging methods improving accuracy and reducing uncertainties of reservoir evaluation and characterization. Efficient implementation of these techniques is explained considering resolution/precision and limitations of measurement physics. Best practices for logging in this type of formation are recommended with guide-lines and examples. Depending on well category (exploration, semi-exploration, appraisal or development), appropriate and optimum logging programs can be designed and sequentially performed to acquire full set of necessary data/information. Latest generation of logging tools, in sonic, nuclear magnetic resonance, accelerator-neutron, formation-tester and analysissampling techniques, which offer significantly better evaluation, are proposed in integrated and optimized methodology. All of advanced logging tools may not be needed systematically for all types of wells; selective criteria are analyzed according to defined objectives/needs, reservoir particularities or/and sequential investigation results. Data/information provided by tool answers-measurements are linked to key equations that will be accurately solved in different workflow implemented within the framework of formation evaluation, reserves estimation, completion selection, stimulation design and enhanced production projects. This approach could be considered as guide lines for preparation of specific tool combinations and adequate logging programs fundamental for tight sands potential assessment and important management decisions.

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Section: -Sonicmentioning

confidence: 99%

Optimum Logging Programs in Tight Sands

Tchambaz

2009

EUROPEC/EAGE Conference and Exhibition

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Sonic logging in deviated boreholes penetrating an anisotropic formation: Laboratory study

2007

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Development of deepwater fields requires drilling deviated or horizontal wells. Many formations are highly anisotropic, that is, the P-and S-wave velocities vary with propagation direction. Sonic logs acquired in these wells need to be corrected for anisotropy effects before the logs can be used in formation evaluation and seismic applications. In this study, we use a laboratory model made of an orthorhombic Phenolite block to study acoustic logging in deviated wells. We first measure the qP-, qSV-, and SH-wave group velocities by using body waves at angles of 0°, 15°, 30°, 45°, 60°, 75°, and 90°relative to the slowest P-wave principal axis of the Phenolite block. We then drill holes at the same angles in the block. We record monopole and dipole sonic waveforms in these holes and extract the qP-, qSV-, SH-, and Stoneleywave velocities by using the slowness-time semblance method. The velocities measured through the use of monopole logging and dipole logging vary with borehole deviations. We find that an equivalent transversely isotropic ͑TI͒ model can fit the measured qP-, qSV-, and Stoneley-wave velocities very well. The S-wave velocities at low to medium borehole deviations can be used to differentiate an orthorhombic material from a TI one.

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Applying Slim Dipole Sonic Tool to Evaluate Hydraulic Fracture Geometry and Orientation Using the Differential Sonic Method

Al-Yaarubi

Bimani

Rahbi

et al. 2022

Day 2 Wed, January 12, 2022

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Successful hydraulic fracturing is critical for hydrocarbon recovery from tight reservoirs. Fracture geometry is one essential quality indicator of the created fracture. The geometry provides information about the size of the created fracture and containment and verifies the pre-job modeling. Different techniques are applied to determine fracture geometry, and each has its own advantages and limitations. Due to its simplicity, the radioactive tracer log is commonly used to determine fracture placement and fracture height. Its main drawbacks include shallow depth of investigation, time dependency, and the requirement for multiple interventions for multistage fracturing operations. The crosswell microseismic technique probes a larger volume and it is potentially capable of providing fracture height, length, and orientation. Operational complexity and long processing turnaround time are the main challenges of this technique. Time-lapse shear slowness anisotropy analysis is an effective method to determine hydraulic facture height and orientation. In this technique, the shear slowness anisotropy is recorded before and after the fracture is created. The observed shear anisotropy difference indicates the intervals where the fractures were created, allowing these intervals lengths to be measured. Combining this analysis with gyroscopic data allows determining the fracture orientations. Compared to a tracer log, the differential casedhole sonic anisotropy (DCHSA) has a deeper depth of investigation, and it is time independent. Thus, the repeated log can be acquired at the end of the multistage fracturing operations. Compared to the microseismic technique, this new technique provides more precise fracture height and orientation. The new generation slim dipole sonic technology of 2.125-in. diameter extends the applicability of the DCHSA technique to smaller casing sizes. The shear differential method was applied to a vertical well that targeted the Athel formation in the south of the Sultanate of Oman. This formation is made of silicilyte and is characterized by very low permeability of about 0.01 md on average. Thus, hydraulic fracturing plays a critical role for the economic oil recovery in this reservoir. Aiming to achieve a better zonal contribution, the stimulation design was changed from a limited number of large fractures to an extensive multistage fracturing design in the subject well. Sixteen hydraulic fracturing stages were planned. The DCHSA was applied to provide accurate and efficient fracture geometry evaluation. The DCHSA accurately identified fracture intervals and their corresponding heights and orientations. This enabled effectively determining the created fracture quality and helped explain the responses of the production logs that were recorded during the well test. This study provided a foundation for the placement and completion design of the future wells in the subject reservoir. It particularly revealed adequate fracturing intervals and the optimum number of stages required to achieve optimum reservoir coverage and avoid vertical overlapping.

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Slowness‐frequency‐projection logs: A QC for accurate slowness estimation and formation property identification

Cited by 4 publications

References 5 publications

Optimum Logging Programs in Tight Sands

Optimum Logging Programs in Tight Sands

Sonic logging in deviated boreholes penetrating an anisotropic formation: Laboratory study

Applying Slim Dipole Sonic Tool to Evaluate Hydraulic Fracture Geometry and Orientation Using the Differential Sonic Method

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