Estimation of permeability and effective porosity logs using deep autoencoders in borehole image logs from the brazilian pre-salt carbonate

2018 ◽  
Vol 170 ◽  
pp. 315-330 ◽  
Author(s):  
Manuel Blanco Valentín ◽  
Clécio R. Bom ◽  
André Luiz Martins Compan ◽  
Maury Duarte Correia ◽  
Candida Menezes de Jesus ◽  
...  
2015 ◽  
Author(s):  
Girija K. Joshi ◽  
Mihira N. Acharya ◽  
Marie Van Steene ◽  
Sandeep Chakravorty ◽  
Christophe Darous ◽  
...  

Abstract The deep organic-rich calcareous Kerogen of North Kuwait, a continuous 50ft thinly alternating carbonate – organic-rich argillaceous sequence, is not only a source rock but has gained importance as potential reservoirs themselves of typical unconventional category. Resource play or Kerogen characterization relies on quantifying total organic carbon (TOC) and estimating accurate mineralogy. This paper describes the first attempt to directly measure total organic carbon of the Limestone-Kerogen sequence. For the present study, empirical estimations of TOC have been carried out based on conventional log measurements and nuclear magnetic resonance (NMR). The introduction of a new neutron-induced capture and inelastic gamma ray spectroscopy tool using a very high-resolution scintillator and a new type of pulsed neutron generator for the deep unconventional kerogen resources have provided a unique opportunity to measure a stand-alone quantitative TOC value using a combination of capture and inelastic gamma ray spectra. In this process, Inorganic Carbon Content (ICC) is estimated by using elemental concentrations measured by this logging tool in addition to measuring Total Carbon, and this value is subtracted from the measured total carbon to give TOC. The advanced elemental spectroscopy tool measurements were first used to determine accurately the complex mineralogy of the layered carbonate and organic-rich shale sequence. Extensive laboratory measurements of core / cuttings data were used to calibrate the petrophysical evaluation and capture the heterogeneity seen on borehole image logs. The final analysis shows considerable improvements compared to conventional empirical estimation. Once the mineralogy is properly determined, the log-derived TOC matches very well with core measured TOC. This technique has provided a new direct and accurate log-derived TOC for Kerogen characterization. The application has a potential to be used for CAPEX optimization of the coring in future wells. This technique can also be applied in HPHT and High-angle horizontal wells, which can overcome challenging coring difficulties in horizontal wells.


GeoArabia ◽  
1997 ◽  
Vol 2 (1) ◽  
pp. 19-34
Author(s):  
Rashid Al-Busaidi

ABSTRACT Early water breakthrough has occurred in the Lower Cretaceous carbonate reservoirs (Aptian Shu’aiba Formation) in Yibal and Lekhwair fields, north Oman. Borehole Image logs were run in more than 10 horizontal wells in each field to investigate the role of faults and fracture systems, as well as facies variations and sedimentary features. These logs indicated the presence of highly-fractured zones with both open and cemented fractures. The fractures have orientations consistent with fault patterns interpreted from 3-D seismic data. High density fractured zones, in most cases, correspond to faults, some of which are below seismic resolution. The presence of fractures and/or fracture zones is the primary cause of early water breakthrough. Improved production performance was achieved by perforating non-fractured intervals to avoid early high water cuts.


2021 ◽  
Author(s):  
Trevor Klaassen ◽  
Jackson Haffener ◽  
Jarret Borell ◽  
Chad Senters

Abstract In multi-stage plug-and-perf horizontal well completions, there are a multitude of moving parts and variables to consider when evaluating performance drivers. Properly identifying performance drivers allows an operator to focus their efforts to maximize the rate of return of resource development. Typically, well-to-well comparisons are made to help identify performance drivers, but in many cases the differences are not clear. Identifying these drivers may require a better understanding of performance variability along a single lateral. Data analytics can help to identify performance drivers using existing data from development activities. In the case study below, multiple diagnostics are utilized to identify performance drivers. A combination of completion diagnostics including oil and water tracers, stimulation data, reservoir data, 3D seismic, and borehole image logs were collected on a set of wells in the early appraisal phase of a field. Using oil tracers as the best indication of stage level performance along the laterals, data analytics is applied to uncover the relationships between the tracers and the numerous diagnostics. After smoothing was applied to the dataset, trends between oil tracer recovery, several independent variables and features seen in image logs and 3D seismic were identified. All the analyses pointed to decreasing tracer recovery, and likely decreased oil production, near faulted areas along each lateral. A random forest model showed a moderate prediction power, where the model's predicted tracer recovery on blind stages was able to explain 54% of the variance seen in the tracer response (r2=0.54). This analysis suggests the identification of certain faulted areas along the wellbore could lead to ways of improving individual well economics by adjusting completion design in these areas.


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