Formation Evaluation in Gas-Bearing Reservoirs Drilled with Na/K Formate WBM, Using LWD Time-Lapse Data Acquisition

Fakolujo, Kehinde M; Al-Belowi, Ali Rashed; Gzara, Kais; Onuigbo, Lsd Oluchukwu; Pasaribu, Ihsan Taufik

doi:10.2118/172140-ms

Cited by 2 publications

(1 citation statement)

References 11 publications

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“…This workflow has been extended further to include non-consonant measurements (Al- Daghar et al 2015) and provide a number of other useful quantities, including, but not limited to, invasion-independent variates or hybrid measurements and moveable fluid types and volumes, as described in (Kraishan et al 2014;Fakolujo et al 2014aFakolujo et al , 2014b.…”

Section: Time-lapse Acquisition and Analysis Of Lwd Datamentioning

confidence: 99%

Maximizing Information through Data Driven Analytics in Petrophysical Evaluation of Well Logs

Jain

Gzara

Makarychev

et al. 2015

SPE Annual Technical Conference and Exhibition

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Modern logging data are characterized by abundance and multiple dimensions: spatial, temporal, and physical. Traditional interpretation workflows for logging data are often limited in their scope and flexibility and use only a subset of the data dimensions, either by choice or necessity. Furthermore, the various deterministic or stochastic workflows typically rely on preconceived rock and fluid models. When those a priori models do not fit the data, confusion can ensue, whereas it is obvious that the correct model is buried somewhere in the "big logging data."To overcome these limitations, new symbiotic approaches using domain expertise and data analytics ("domain-analytics") have been developed. Domain experts use those novel approaches to develop data-driven workflows to explore and mine complex logging datasets for latent but interpretable information. Once validated to be idempotent, the expert workflows that respect both the acquired data and domain knowledge can be packaged into new classes of answers products.In this paper, the novel approaches, along with the examples of new answer products, are presented. These include 1) the automated spatial search for common modes and repeated patterns in the single or multi-well nuclear magnetic resonance (NMR) data, 2) the generation of a data-driven fluid model using time-lapse logging data acquired during multiple passes over the same formation, and 3) the creation of interpretive class-based models using definitive core data that could be propagated to continuous log data for a richer petrophysical interpretation. Big Logging DataRock formations are discontinuous, heterogeneous, anisotropic media resulting from a long and often complex geological history. To understand and quantify the underlying rock matrix and fluid distribution, petrophysicists derive various quantities of interest (Q) such as lithology, pore-size distribution, fluid characteristics, and volumetrics from a number of log measurements (M), as shown in Fig. 1. Those log measurements (M) are the direct transform (g) of acquired physical data (A), whereas the transforms (h) of subsurface quantities from log measurements are mostly empirical and/or model based.Transforms between log measurements and petrophysical quantities are not only difficult to establish but are also limited in scope. Difficulty lies in the fact that most of these relationships are empirical, created by fitting observed results and measured properties in laboratories using cores and fluid samples.

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Section: Time-lapse Acquisition and Analysis Of Lwd Datamentioning

confidence: 99%

Maximizing Information through Data Driven Analytics in Petrophysical Evaluation of Well Logs

Jain

Gzara

Makarychev

et al. 2015

SPE Annual Technical Conference and Exhibition

Self Cite

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Invasion Corrected Fluid Saturations, from Standalone Consonant Nuclear Measurements, Using Canonical-Correlation Analysis (CCA) of Logging-While-Drilling (LWD) Time-Lapse Data

Al-Daghar

Atfeh

Aal

et al. 2015

SPE Middle East Oil &Amp; Gas Show and Conference

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Fluids saturations in new wells are usually derived from resistivity measurements, using locally selected or calibrated resistivity equations. Some drawbacks to resistivity measurements are multiple environmental corrections in high-angle wells, thin beds, washed-out boreholes, and complex invasion profiles. Moreover, the accuracy of Archie's equation may suffer from variable cementation and saturation exponents and unknown water salinity.A recently introduced comprehensive suite of consonant logging-while-drilling (LWD) nuclear measurements with linear mixing laws, is used to solve for minerals and fluid volumes independent of resistivity measurements. This requires the petrophysical properties of all the fluids present to be known. Another requirement for accurate formation evaluation is the mud filtrate invasion correction. While this poses no problem for multiple depths of investigation (MDOI) resistivity measurements that also read deep into the formation, there is no set rule to determine the geometrical factor of nuclear measurements to account for invasion. This paper describes an LWD time-lapse data acquisition scheme to circumvent invasion effects on nuclear measurments and to eliminate the need to specify some of the unknown petrophysical properties of the fluids present. Canonical-correlation analysis (CCA) is used to identify canonical variates that remain unchanged between a primary drill pass and a secondary wipe pass. Because these variates remain unchanged between passes, they are independent of the formation invasion status, and can represent the properties of either the virgin or the flushed zone, but not a combination of the two, as is typically the case of measurements whose volume of investigation samples both zones. These invasion-independent variates are then used in the petrophysical evaluation, instead of the standard logs which may otherwise vary with time.We used CCA in 2 carbonate examples to show how to 1) correct bulk density measurement in corkscrew borehole, 2) correct MDOI capture sigma measurements for invasion effect, and 3) perform volumetric formation evaluation without knowledge of the water and hydrocarbon endpoints and invasion parameters. The CCA approach is a significant new development in well log interpretation that removes uncertainties associated with unknown mineral or fluids petrophysical properties and invasion status.

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Formation Evaluation in Gas-Bearing Reservoirs Drilled with Na/K Formate WBM, Using LWD Time-Lapse Data Acquisition

Cited by 2 publications

References 11 publications

Maximizing Information through Data Driven Analytics in Petrophysical Evaluation of Well Logs

Maximizing Information through Data Driven Analytics in Petrophysical Evaluation of Well Logs

Invasion Corrected Fluid Saturations, from Standalone Consonant Nuclear Measurements, Using Canonical-Correlation Analysis (CCA) of Logging-While-Drilling (LWD) Time-Lapse Data

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