Advanced Mud Logging (AML) aids formation evaluation and drilling, and yields precise hydrocarbon fluid composition
Abstract and Figures
While traditional mudlogging techniques provide largely qualitative data, the prime objective of Advanced Mud Logging (AML) is to provide quantitative real time measurements in aid of a complete formation evaluation. To achieve this, wellsite mudlogging technologies have been enhanced, and various techniques which historically were limited to laboratories, have been adapted for well site usage. AML well site techniques thus include: (1) high frequency, improved accuracy monitoring of drilling parameters; (2) enhanced cuttings image acquisition and processing; (3) direct measurements on cuttings, including graindensity, spectral GR, NMR, XRD, XRF; and (4) sophisticated mud gas analysis capabilities.
We describe the main system components developed and present some results of the first pilot tests done in Saudi Arabia with AML techniques and a dedicated AML unit. Examples in the four areas mentioned above illustrate and confirm the potential of AML. On one special technology test well, different systems, from two different companies, were run in parallel to establish the merits and possible limitations of especially the hydrocarbon analysis systems.
One of the most striking examples of the quality of AML is a perfect match between the hydrocarbon fluid composition determined from mud gas returns, and those subsequently obtained from PVT measurements on wireline fluid samples. To achieve this, AML technology developers in the industry advanced across the whole process chain affecting such quantification. First and foremost, improving sample extraction and handling, combined with enhanced calibration procedures, to convert from in situ to surface conditions. Second, in addition to sampling both the return mud flow and the inflow, a more precise tracking of flowrates and system volumes was made possible with modern operating systems. Third, adding a mass spectrometer to the gas chromatograph, improved the final measurement potential.
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... Embora existam uma série de trabalhos visando a aplicação de métodos para melhorar os processos de análises no contexto da perfuração de poços de petróleo (LOERMANS et al., 2011;MARSALA et al., 2011aMARSALA et al., , 2011bLOERMANS et al., 2012), a indústria do petróleo ainda carece de estudos voltados mais à análise de cavings e como tornar o processo de identificação e caracterização mais rápidos e assertivos. Um dos poucos trabalhos relacionados ao tema é o de Skea et al. (2018), por exemplo, que usa uma abordagem de processamento de imagens para caracterizar os tipos de cavings com base no arredondamento e esfericidade desses fragmentos de rocha. ...
... Embora existam uma série de trabalhos visando a aplicação de métodos para melhorar os processos de análises no contexto da perfuração de poços de petróleo (LOERMANS et al., 2011;MARSALA et al., 2011aMARSALA et al., , 2011bLOERMANS et al., 2012), a indústria do petróleo ainda carece de estudos voltados mais à análise de cavings e como tornar o processo de identificação e caracterização mais rápidos e assertivos. Um dos poucos trabalhos relacionados ao tema é o de Skea et al. (2018), por exemplo, que usa uma abordagem de processamento de imagens para caracterizar os tipos de cavings com base no arredondamento e esfericidade desses fragmentos de rocha. ...
... This technology, mud gas logging, has been used in the petroleum industry for decades [12][13][14] and has continuously and significantly improved over time [15,16]. Petroleum companies use advanced mud gas logging (AMG) to collect data during drilling, including measuring molecular compositions of gases and making real-time corrections to eliminate the effects of gas recycling and various drilling artifacts [3,7,[17][18][19][20][21]. ...
Drill-bit metamorphism (DBM) is the process of thermal degradation of drilling fluid at the interface of the bit and rock due to the overheating of the bit. The heat generated by the drill when drilling into a rock formation promotes the generation of artificial hydrocarbon and non-hydrocarbon gas, changing the composition of the gas. The objective of this work is to recognize and evaluate artificial gases originating from DBM in wells targeting oil accumulations in pre-salt carbonates in the Santos Basin, Brazil. For the evaluation, chromatographic data from advanced mud gas equipment, drilling parameters, drill type, and lithology were used. The molar concentrations of gases and gas ratios (especially ethene/ethene+ethane and dryness) were analyzed, which identified the occurrence of DBM. DBM is most severe when wells penetrate igneous and carbonate rocks with diamond-impregnated drill bits. The rate of penetration, weight on bit, and rotation per minute were evaluated together with gas data but did not present good correlations to assist in identifying DBM. The depth intervals over which artificial gases formed during DBM are recognized should not be used to infer pay zones or predict the composition and properties of reservoir fluids because the gas composition is completely changed.
Analysis of drill-cuttings collected on the rig has always been the most basic, yet most direct means of understanding the subsurface within its own limitations. However, automation enabled by digital transformation of this aspect of mud logging has greatly increased the importance of this data. A futuristic preview is being presented for the repositioning and value showcasing of most basic and widely available data, i.e., cuttings with digital enablement.
Cost-efficient characterization with lean sample preparation, reducing the adverse environmental imprint to near real-time formation evaluation leading to enhanced well placement and completion design is reshaping the old-school mudlogging with direct detection and quantification of minerals, total organic carbon (TOC), kerogen content and elemental composition; often minimizing the requirement for time-and-cost intensive wireline logging. Labor-intensive sample collection is getting automated, and subjective and descriptive interpretation per experience of mud-logger is giving way to digital, objective interpretation, ready to be integrated with logging-while-drilling data in real-time.
In addition to the X-Ray Fluorescence & Diffraction; newer technologies like Diffused Reflectance Infrared Fourier Transform Spectroscopy (DRIFTS) are being incorporated in wellsite set-up with reduced footprint on rig and minimized usage of chemicals. Unique automated process can analyze high resolution digital images to deliver plethora of information in minimum time; often augmented with the help of artificial intelligence. A futuristic view with building blocks of the automated interpretation process is presented.
Examples from different steps needed to achieve automation are provided, from sample preparation to digital analysis through machine learning for a holistic futuristic vision to highlight digital enablement in delivering the well-objectives in cost-efficient and timely manner honoring the changing market dynamics. This foundational cutting analysis (Geology 101) vision would drive further adavnces in this field.
Manual sampling rock cuttings off the shale shaker for lithology and petrophysical characterization is frequently performed during mud logging. Knowing the depth origin where the cuttings were generated is very important for correlating the cuttings to the petrophysical characterization of the formation. It is a challenge to accurately determine the depth origin of the cuttings, especially in horizontal sections and in coiled tubing drilling, where conventional logging while drilling is not accessible. Additionally, even in less challenging drilling conditions, many factors can contribute to an inaccurate assessment of the depth origin of the cuttings. Inaccuracies can be caused by variation of the annulus dimension used to determine the lag time (and thus the depth of the cuttings), by the shifting or scrambling of cuttings during their return trip back to the surface, and by the mislabelling of the cuttings during sampling. In this work, we report the synthesis and application of polystyrenic nanoparticles (NanoTags) in labeling cuttings for depth origin assessment. We have successfully tagged cuttings using two NanoTags during a drilling field test in a carbonate gas well and demonstrated nanogram detection capability of the tags via pyrolysis-GCMS using an internally developed workflow. The cuttings depth determined using our tags correlates well with the depth calculated by conventional mud logging techniques.
During a drilling operation, rock cuttings are often sampled off a shale shaker for lithology and petrophysical characterization. These analyses play an important role in describing the subsurface; and it is important that the depth origin of the cuttings be accurately determined. Traditionally, mud-loggers determine the depth origin of the sampled cuttings by calculating the lag time required for the cuttings to travel from the bit to the surface. These calculations, however, can contain inaccuracies in the depth correlation due to the shuffling and settling of cuttings as they travel with drilling fluid to the surface, due to unplanned conditions like drilling an overgauge hole, and due to other unforeseen drilling events, especially critical in horizontal sections. We therefore aimed to remedy these inaccuracies by developing a series of styrene-based nanoparticles that tagged the cuttings as they were generated at the drillbit. These “NanoTags” were tested while drilling in Q4, 2019; and the results indicated that the NanoTags did in fact have the potential to identify some systematic errors compared with traditional mud logging calculations.
Petrophysical Characterization of Reservoir Rocks by Measurements on Cuttings" - OMC ‘97 - Offshore Mediterranean Conference
- A F Marsala
- Meazzao
- Rossie
- Brignolim
- J Santarellif
- P Agip S
Marsala, A. F., Meazza O., Rossi E., Brignoli M., Santarelli F.J., AGIP S.p.A. " Petrophysical Characterization of Reservoir Rocks by
Measurements on Cuttings " -OMC '97 -Offshore Mediterranean Conference' -Ravenna, Italy, March 19-21, 1997
Loermans and Kanj; Porosity measurements on cuttings from X-ray CT scans: study highlights; SPE Technical Symposium Dhahran, Saudi Arabia
- Touati
- Funk Siddiqui
Touati, Siddiqui, Funk, Loermans and Kanj; Porosity measurements on cuttings from X-ray CT scans: study highlights; SPE Technical
Symposium Dhahran, Saudi Arabia; May 2004.
Petrophysical Characterization of Reservoir Rocks by Measurements on Cuttings
- A F Marsala
- O Meazza
- E Rossi
- M Brignoli
- F J Santarelli
- P Agip S
Marsala, A. F., Meazza O., Rossi E., Brignoli M., Santarelli F.J., AGIP S.p.A. "Petrophysical Characterization of Reservoir Rocks by
Measurements on Cuttings" -OMC '97 -Offshore Mediterranean Conference' -Ravenna, Italy, March 19-21, 1997