Layer | Fill | Outline |
---|
Map layers
Theme | Visible | Selectable | Appearance | Zoom Range (now: 0) |
---|
Fill | Stroke |
---|---|
Collaborating Authors
Slim Pulsed Neutron Spectroscopy Integrated with Wellbore Imaging to Provide Synthetic Core in Slim Boreholes and Cased-Hole Environment
Saleh, Khaled (Schlumberger) | Cavalleri, Chiara (Schlumberger) | Espinosa, Hugo (Schlumberger) | Ghanim, Mohamed (Schlumberger) | Galal, Mahmoud (Schlumberger) | Gomes, Renata (Schlumberger) | Morad, Aly (Schlumberger)
Abstract Recent advancement in logging technology and data analytics enables measuring a comprehensive set of formation petrophysical properties and rock composition in cased-hole environments. Using state-of-art pulsed neutron logging technology and processing algorithms enables recording capture and inelastic elemental spectroscopy for rock elemental concentrations, including total organic carbon, detailed mineralogy and matrix properties, simultaneously to sigma and other neutron-based outputs. The integration of the interpreted lithology from cased-hole elemental spectroscopy data with electrofacies from high-resolution imaging tools recorded in the open-hole provides the characterization of heterogeneity challenges by building a synthetic core in old wells with limited data gathering from open-hole logging or absence of conventional coring. An effective way to incorporate those measurements has been developed and adapted to the use of cased-hole spectroscopy logs. The dry weight elemental fractions measured by the advanced pulse neutron technology are corrected for wellbore contribution and converted into dry weight mineralogical outputs. Using an automated processing workflow converts the capture and inelastic gamma-ray yields from the energy spectrum measured behind casing into the dry weight of elements and mineral fractions in the formation. The computed mineralogical outputs are then defined based on a standardized ternary diagram approach to developing dry-weight mineralogy-based lithofacies. This classification is then combined with the calibrated micro-resistivity image data collected during the open-hole logs evaluation to present a high-resolution rock typing (after Kumar & Kear). The resulting log is dry weight mineralogy-based high-resolution lithofacies that contain vital information to support geological and petrophysical reserves modeling adjustments during development and production. The paper demonstrates the applicability of the method to cased-hole environments in fields with mixed lithology and complex geological background. Once a robust lithofacies classification is achieved, this is applied for detailed stratigraphic analysis, well-to-well correlation, or refined static reservoir modeling. A standardized mineral-based facies scheme guides the selection of higher completion-quality intervals, otherwise difficult to define in old wells with limited original evaluation. Besides, thin beds that were previously bypassed can be detected and characterized for high-resolution net pay calculation leveraging the high-resolution lithofacies output from this approach. The lithofacies classification (synthetic core) provides important input to the study of reservoir connectivity in the development phase and production optimization. Moreover, a synthetic core description would be critical when reassessing mature fields and defining completion and production strategies where core data is not available. The approach and workflow can be implemented in various cases as a cost-effective solution in multiple scenarios and different formation types.
- Asia (0.93)
- North America > United States > Texas (0.28)
- Geology > Geological Subdiscipline > Mineralogy (1.00)
- Geology > Rock Type > Sedimentary Rock > Clastic Rock > Mudrock (0.31)
- Geophysics > Borehole Geophysics (1.00)
- Geophysics > Seismic Surveying > Borehole Seismic Surveying (0.85)
Abstract In recent years, operators have produced large quantities of hydrocarbon from organic shale reservoirs. Horizontal drilling and multi-stage stimulations, targeting sections with superior reservoir quality (RQ) and completion quality (CQ), have been proven as key to their development. Organic mudstones, often referred to as shales, are fine-grained sedimentary rocks with total organic carbon (TOC) above 2% and typically complex mineralogy, consisting of a mixture of biogenic and terrigenous sources of siliciclastic and/or carbonate debris, affected by diagenetic processes. These rocks are highly heterogeneous especially perpendicular to bedding. Although numerous cores and outcrops have been studied and described, there is no published mineralogy-based classification scheme for organic mudstones. This paper defines a methodology for creating a detailed mineralogy-based description for organic mudstones using inorganic mineralogy, primarily X-ray diffraction (XRD) and geochemical log data. The proposed classification scheme is based on a ternary diagram created specifically for organic mudstones by using a combination of core- and log-based mineralogical relationships. The primary classes are siliceous mudstone, carbonate-rich mudstone and argillaceous mudstone. Sub-classes are based on relative amounts of these three mineral groups. A mineralogy-based classification may help provide a better understanding of depositional conditions and identify target zones for completion. A common metric for the description of organic mudstones will also facilitate comparison of such reservoirs from different areas, formations, basins, and continents. A secondary objective is to provide a log display that flags other descriptive parameters that impact RQ, CQ and/or operational efficiency. A strong correlation exists between mineralogy and CQ in most U.S. shale plays. The correlation between mineralogy and RQ is not as strong. RQ appears to be driven by both compositional and textural components of organic mudstones. The log displays presented here provide a consistent description of the organic mudstone section and the input necessary for proper decision making when planning a drilling development project.
- North America > United States > Texas (1.00)
- North America > Canada (0.69)
- Asia (0.68)
- Geology > Geological Subdiscipline (1.00)
- Geology > Rock Type > Sedimentary Rock > Clastic Rock > Mudrock > Shale (0.51)
- North America > United States > Texas > West Gulf Coast Tertiary Basin > Eagle Ford Shale Formation (0.99)
- North America > United States > Texas > Sabinas - Rio Grande Basin > Eagle Ford Shale Formation (0.99)
- North America > United States > Texas > Permian Basin > Wolfcamp Formation (0.99)
- (8 more...)
- Reservoir Description and Dynamics > Unconventional and Complex Reservoirs > Shale oil (1.00)
- Reservoir Description and Dynamics > Unconventional and Complex Reservoirs > Shale gas (1.00)
- Reservoir Description and Dynamics > Reservoir Characterization > Exploration, development, structural geology (1.00)
- (2 more...)
Exploiting Slim Pulsed Neutron Spectroscopy for Unlocking Reservoir Potential in Brownfields: Two Examples from Gulf of Suez Offshore Field in Egypt
Ameen, Mohamed (General Petroleum Company) | Atwa, Eslam (General Petroleum Company) | Youssif, Youssif (General Petroleum Company) | Hakim, Emad Abdel (General Petroleum Company) | Farouk, Mohamed (General Petroleum Company) | Ghadiry, Sherif (Schlumberger) | Saleh, Khaled (Schlumberger) | Morad, Aly (Schlumberger)
Abstract For more than 40 years, pulsed neutron spectroscopy has been primarily used in reservoir management to determine hydrocarbon saturation profiles, tracking reservoir depletion, and planning workover activities to diagnose production problems such as water influx. Legacy pulsed neutron tools used to provide this information for more than four decades, but they were challenged when a mixed lithology reservoir is encountered, complex completions, unknown borehole conditions, and poor cement integrity in cased boreholes. This paper presents two successful field examples and applications using the advanced slim pulsed neutron spectroscopy to precisely determine multiphase contacts in a complex geological structure, provide current hydrocarbon saturation independent of the quality of cement behind the casing, and identifying bypassed hydrocarbon. This was of paramount importance in understanding current reservoir fluid distribution to reveal the true potential of this offshore brownfield located in the Gulf of Suez, Egypt. An integrated approach and candidate well selection were done that resulted in selecting two candidate wells that had poor cement quality behind casing, heterogeneous carbonate reservoir with mixed lithology, and uncertain fluid contacts in a complex reservoir structure. These combined borehole and reservoir conditions resemble challenges for capturing this crucial information with high confidence using the legacy pulsed neutron tool, and therefore required an advanced technology that can overcome these challenges using a single logging mode at twice the logging speed of any current pulsed neutron technology available in the industry. Based on the results, a workover campaign was implemented in this mature field to increase overall oil production with very efficient cost control, especially with this unprecedented time the O&G industry is going through. An integrated approach was set that resulted in the selection of two wells for the saturation determination logging tool deployment. Detailed high-resolution mineralogy, self-compensated total porosity and sigma, fluid type identification, and multiphase fluid saturation was obtained with high precision behind cased borehole independent of cement integrity and borehole fluid reinvasion. The results provided crucial information as an input to the integrated reservoir engineering approach which revealed around a 100-m net oil interval which was previously overlooked due to relatively low resistivity. Besides, fluids contacts were evaluated that confirmed the development of a secondary gas cap and the water encroachment direction. This technology can be further applied to more brownfields provided the right candidate selection is done to understand the potentiality of the field which would increase the recovery factor of the brownfields that represent almost more than 65% of the oil and gas fields around the world.
- Asia > Middle East > Saudi Arabia (1.00)
- Africa > Middle East > Egypt > Gulf of Suez (0.28)
- Africa > Middle East > Egypt > Suez Governorate > Suez (0.24)
- Geology > Geological Subdiscipline (1.00)
- Geology > Mineral (0.94)
- Geology > Rock Type > Sedimentary Rock > Carbonate Rock (0.48)
- Geology > Rock Type > Sedimentary Rock > Clastic Rock (0.46)
- Asia > Middle East > Saudi Arabia > Eastern Province > Arabian Basin > Widyan Basin > Hamd Field (0.99)
- Africa > Middle East > Egypt > South Sinai Governorate > Lagia Field > Thebes Formation (0.99)
- Africa > Middle East > Egypt > Gulf of Suez > Gulf of Suez Basin > Bakr Field (0.99)
- North America > United States > Texas > West Gulf Coast Tertiary Basin > Egypt Field (0.97)
- Reservoir Description and Dynamics > Reservoir Characterization > Exploration, development, structural geology (1.00)
- Reservoir Description and Dynamics > Improved and Enhanced Recovery (1.00)
- Reservoir Description and Dynamics > Formation Evaluation & Management > Open hole/cased hole log analysis (1.00)
Enhancing Formation Testing and Sampling Operations Through the Use of Log-Derived High-Resolution Mineral-Based Lithofacies Mapping
Elshahawi, Hani (Shell International E&P) | Donaghy, Eileen M. (Shell Offshore Inc.) | Guillory, Christina Marie (Shell E&P Co.) | Kear, George Richard | Kumar, Anish (Schlumberger) | Ardila, Mario (Schlumberger Oilfield Services) | Williamson, David (Schlumberger Oilfield Services) | Briscoe, Brian (Schlumberger Oilfield Services) | Cantwell, Wesley Allan (Core Laboratories Inc.)
Abstract Wireline formation testers are being routinely used today in a range of applications that spans pressure and mobility profiling; downhole fluid sampling and downhole fluid analysis; interval pressure transient testing; and micro-stress testing. These tools are able to collect large amount of data at multiple depths thus helping to quantify changes in rock and fluid properties along the wellbore, to define hydraulic flow units, and to understand the reservoir architecture. A key input into the planning of wireline formation tester operations is an accurate understanding of the subsurface lithology, including subtle reservoir internal baffles and barriers. Not only is it necessary to understand where, in depth, the zones of interest exist, but also their compositions. Log-derived high-resolution mineral-based lithofacies can be used to improve the planning of downhole sampling operations and post-operational analysis. These are computed using borehole spectroscopy and high-resolution micro-resistivity image data. The spectroscopy data is used to classify the rocks into dry-weight mineralogy-based lithofacies based on a specifically designed ternary-diagram classification system. Calibrated high-resolution micro-resistivity image data is integrated with the generated dry-weight mineralogy-based lithofacies to compute a final mineral-based high-resolution set of lithofacies. All the computations can be accomplished on a workstation within a short time. The final lithofacies can be presented as a detailed geological column, or be input, as numerical data, for additional computation and modeling. These lithofacies can be used to make sampling and pressure point selections. The speed of computation makes them useable for this purpose. The output can be quickly delivered to the decision makers whether in the office or at a remote location. The geological display of the lithofacies makes it readily usable and preferred for choosing sampling locations, whether for pressure or fluids. The inherent mineralogical content combined with the higher resolution bedding directly addresses the need to identify potential zones of interest otherwise indistinguishable. Critical depositional events such as maximum flooding surfaces, condensed sections, reservoir seals such as marl layers and shales, continuous or interbedded, are immediately identifiable with these lithofacies. The use of log-derived high-resolution mineral-based lithofacies helps place the tool probes and/or packers at optimum formation and depth locations, thereby reducing risk and operating time, easing interpretation, and maximizing data and sample recovery. Introduction As global exploration proceeds to deeper waters and more challenging targets, increasingly more complex rocks and fluids are encountered. It is, therefore, becoming ever more requisite to clearly understand the sub-seismic details of the reservoir. In recent years, wireline formation testers (WFT) have become the default methodology for collecting formation fluid samples previously obtained only from drillstem (DST) or production tests. Pressure testing, sampling, and identification of compartmentalization are of critical importance to reservoir development. Traditional methods of sampling and compartment identification such as drill stem tests and extended well tests often become impractical in deep water settings with costs approaching the costs of new wells and emissions becoming increasingly undesirable. In order to collect representative fluid samples and to decipher the connectivity of compartments, downhole pressure and gradients, downhole fluid analysis, sampling and vertical interference testing are being relied on more and more. In comparison to other tests, downhole sampling operations are easier to plan, and require less lead-time. Wireline formation testers are highly selective, allowing a series of reservoirs to be tested during a single trip into the well. Samples can be taken at low drawdown pressure for greater control, ensuring the sampling process itself minimally disturbs the physical characteristics and phase behavior of the fluid. Other advantages include reduced HSE (health, safety and environment) risks, the reduced need for equipment and personnel, and the lower overall costs.
- Geology > Geological Subdiscipline > Mineralogy (0.77)
- Geology > Rock Type > Sedimentary Rock > Clastic Rock > Mudrock (0.35)
- Reservoir Description and Dynamics > Reservoir Characterization > Exploration, development, structural geology (1.00)
- Reservoir Description and Dynamics > Formation Evaluation & Management > Formation test analysis (e.g., wireline, LWD) (1.00)
- Reservoir Description and Dynamics > Formation Evaluation & Management > Drillstem/well testing (1.00)
A Novel Cost-Effective Stimulation Workflow Unlocks New Perspectives for Matrix Acidizing in Fractured Carbonate Reservoir – A Case Study from Egypt
Hegazy, Amr (General Petroleum Company) | Abdel Hakim, Emad (General Petroleum Company) | Farouq, Mohamed (General Petroleum Company) | Badran, Hesham (General Petroleum Company) | Shalaby, Roshdy (Schlumberger) | ElKaragi, Alaa (Schlumberger) | Saleh, Khaled (Schlumberger)
Abstract Matrix acidizing can effectively stimulate carbonate reservoirs, often resulting in skin factors on the order of –3 to –4. Wormholes can effectively connect the well with the reservoir. However, if the carbonate reservoir is naturally fractured, it will be difficult to generate dominant wormholes using conventional matrix acidizing. Hence, an effective acidizing technique is crucial to handle such heterogeneous carbonate rock, especially if the permeability contrast is vast between the matrix and fracture. This paper exhibits a novel workflow developed by a multidomain team to reveal the true potential of the fractured carbonate reservoir in a heterogeneous complex basin in the Eastern Desert in Egypt called the GoS basin. The new logging program uses high-resolution wellbore imaging, nuclear magnetic resonance (NMR), and casedhole pulsed neutron logging technology and processing algorithms to record capture and inelastic elemental spectroscopy for matrix parameters, detailed mineralogy, and oil saturation. The output of this characterization portrayed complex challenges that prevent having defined acid distribution between the flow zones of the natural fractures and the unfractured matrix due to the permeability contrast of 130:1. The key to success in dealing with such stimulation jobs is choosing the optimal chemical diversion, main acid treatment, pumping placement, and establishing a fit-for-purpose pumping schedule. Many experimental and laboratory tests were performed to prepare a viscous pill to be utilized as temporary isolation for the fracture or the fissures network prior to starting the full acid treatment. In addition to that, employing a passive diverter instead of an active acid-based diverter was a seamless technique to divert the acid away from each zone after pumping. The results of this novel workflow and the new acid technique indicate a sixfold increase in well productivity. The falloff analysis followed by the viscous pill reinforces the potency of the temporary isolation; this aids in treating the lower-permeability layers, which are the candidates for matrix acidizing. The applications of this novel workflow unlock the true potential of the lower-permeability reservoirs and maximize the estimated ultimate recovery. This paper showcases our experiences with the use of this unique recipe in fractured carbonate reservoirs, and in reservoir characterization and provides lessons learned to fill knowledge gaps in this area and provide a complete workflow that can be utilized everywhere worldwide.
- Asia > Middle East > Saudi Arabia (1.00)
- Africa > Middle East > Egypt (1.00)
- Geology > Structural Geology (1.00)
- Geology > Petroleum Play Type > Unconventional Play > Fractured Carbonate Reservoir Play (0.81)
- Geology > Rock Type > Sedimentary Rock > Carbonate Rock (0.66)
- Asia > Middle East > Saudi Arabia > Eastern Province > Al-Ahsa Governorate > Arabian Basin > Widyan Basin > Ghawar Field > Lower Fadhili Formation (0.99)
- Asia > Middle East > Saudi Arabia > Eastern Province > Al-Ahsa Governorate > Arabian Basin > Widyan Basin > Ghawar Field > Khuff D Formation (0.99)
- Asia > Middle East > Saudi Arabia > Eastern Province > Al-Ahsa Governorate > Arabian Basin > Widyan Basin > Ghawar Field > Khuff C Formation (0.99)
- (4 more...)