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Collaborating Authors
Paleozoic
Detailed Mineralogy and Organic Carbon Detection Through Casing Using Pulsed Neutron Technology - A Case Study in a Carbonate Formation (KY)
Mendez, Freddy E. (Baker Hughes Incorporated) | Siddiqui, Aamir (Baker Hughes Incorporated) | Hanif, Amer (Baker Hughes Incorporated) | Longo, John (Baker Hughes Incorporated) | McGlynn, Ian (Baker Hughes Incorporated) | Gade, Sandeep (Baker Hughes Incorporated) | Blood, David R. (EQT)
Abstract Spectral analysis of natural and stimulated gamma rays is a well-established open-hole technology that enables accurate mineral characterization and petrophysical evaluation of conventional and unconventional reservoirs. The determination of detailed mineralogy in the cased-hole environment, however, has been a challenge because of the significantly increased uncertainties caused by the additional attenuation and contribution effects of casing and cement that are observed in the gamma ray spectra. The acquired spectral gamma ray data is processed with proprietary algorithms that are based on a combination of lab experiments and modeled tool response standards. The resulting elemental composition, corrected for the cased-hole environment, is further processed in an expert interpretation system to determine lithology and detailed mineralogy of the target formation. Candidates for this technology include older and newly cased wells where lithology and detailed mineralogy from open-hole logs are not available. This work discusses some aspects of the corrections needed for an accurate quantification of chemical elements from measurements through casing. The impact of casing collars and presence of cement on the spectral data are also discussed. Finally, we report a case study that uses this technology and illustrates a successful mineral characterization of a complex reservoir rock in the United States. Results show good agreement with an x-ray difraction (XRD) analysis of ditch cuttings. The resulting logs were productively used by the operator to understand the siliciclastic influx as well as the distribution of carbonates in the Big Lime formation. The results also show the ability of the methodology to identify organic carbon directly from measurements of the inelastic spectrum in the cased-hole environment. The application of pulsed neutron technology (PNT) in cased holes has, so far, been limited to basic lithology identification. This methodology expands the applicability of the PNT, previously mostly confined to open-hole cases, to the cased-hole environment and enables operators to take full advantage of the valuable information contained in high-resolution inelastic, capture and natural spectra. This enables characterization of hydrocarbon-bearing formations to a level of detail previously possible only from open-hole data.
- Geology > Geological Subdiscipline > Mineralogy (1.00)
- Geology > Rock Type > Sedimentary Rock > Carbonate Rock (0.71)
- Geology > Rock Type > Sedimentary Rock > Clastic Rock (0.68)
- North America > United States > West Virginia > Appalachian Basin > Upper Devonian Shale Basin > Upper Devonian Shale Formation (0.99)
- North America > United States > Tennessee > Appalachian Basin (0.99)
- North America > United States > Pennsylvania > Appalachian Basin > Upper Devonian Shale Basin > Upper Devonian Shale Formation (0.99)
- (12 more...)
- Reservoir Description and Dynamics > Unconventional and Complex Reservoirs (1.00)
- Reservoir Description and Dynamics > Reservoir Characterization > Exploration, development, structural geology (1.00)
- Reservoir Description and Dynamics > Formation Evaluation & Management > Open hole/cased hole log analysis (1.00)
- Health, Safety, Environment & Sustainability > Environment > Naturally occurring radioactive materials (0.93)
Abstract Murzuq Basin is an intractratonic sag basin located in the southwestern part of Libya and considered as one of the major profitable basins in North Africa. The basin has been developed during the Late Precambrian-Early Paleozoic time, which went through various reactivated tectonic events. These events were dominant during the Paleozoic era coincided with regional unconformities and major sea level changes that resulted in complex geological configuration of both structural and stratigraphic. Detailed subsurface analysis implemented utilizing seismic and well log dataset of the concession NC186 to evaluate the main Paleozoic tecto-stratigraphic complexities within the northern part of the basin. This analysis guided to understand the major Paleozoic polyphase tectonic evolution in the area of study. Steep reverse basement faults, folds, positive flower structures and paleohighs and paleolows of glacial topography are evidently indication of the observed large-scale tectonic Paleozoic elements. From this study, the basement faults are anticipated to be genetically related to the Pan African Orogeny in origin and played major controller of all Paleozoic events. These faults are striking NW-SE with a vertical throw up to 300 meters and an oblique fault plane. Late Ordovician glacial valleys encountered in the area with more than seven kilometers of wide, which have eroded more than 500 meters of Middle Ordovician and Cambrian deposits. The incised valleys took place along the strike of the major basement faults in the area. The entire large-scale analyzed elements interpreted to be generated, directly and indirectly, by different tectonic regimes (i.e. compressional, extensional, strike-slip and combination) exclusively during Paleozoic time. Therefore, from the detailed interpretation; six phases are introduced as the main representative tectonic episodes of in the northern part of Murzuq Basin. These tectonic phases and episodes have controlled the petroleum system in the basin and the area of study in particular.
- Phanerozoic > Paleozoic > Cambrian (1.00)
- Phanerozoic > Paleozoic > Ordovician > Upper Ordovician (0.69)
- Geology > Structural Geology > Tectonics (1.00)
- Geology > Structural Geology > Fault (1.00)
- Geology > Geological Subdiscipline > Stratigraphy (1.00)
- (3 more...)
- Africa > Middle East > Tunisia > Berkine Basin (Trias/Ghadames Basin) (0.99)
- Africa > Middle East > Libya > Wadi al Hayat District > Murzuq Basin > Hawaz Formation (0.99)
- Africa > Middle East > Libya > Murzuq District > Murzuq Basin (0.99)
- (4 more...)
- Reservoir Description and Dynamics > Reservoir Characterization > Seismic processing and interpretation (1.00)
- Reservoir Description and Dynamics > Reservoir Characterization > Geologic modeling (1.00)
- Reservoir Description and Dynamics > Reservoir Characterization > Exploration, development, structural geology (1.00)
Abstract Vertical wells are drilled in the In Aminas field in Algeria with various types of drill bits, including polycrystalline diamond compact bits (PDC), tungsten carbide insert bits (TCI), and impregnated (impreg) drill bits. The operator tested a new 6-in impregnated bit with novel cutting structure concepts in an attempt to drill the section in one run. The bit was used on rotary BHA, and high speed motor BHA for two runs in the same section. Both runs did well, and the bit maintained the sharp cutting structure till the TD of the section. The 6-in section comprises mulitple layers of hard abrasive sandstone with unconfined compressive strength up to 35 KPSI, loose shale which is relatively soft and ends with metamorphic rock. The new impregnated bit uses diamond segments imbedded in blades comprising diamond-grit matrix material to create a cutting structure with variable wear along the bit face. This particular combination of diamond and matrix improved overall aggressiveness and durability in the shoulder. To drill efficiently, impregs are paired with high-speed motors or turbines. The new design successfully drilled on two different BHAs. The first was a rotary-packed BHA that drilled 406.8 ft (124 m) at 4.33 ft/hr (1.32 m/hr). The bit didn't show signs of wear and was used on a second BHA with a high-speed motor that drilled another 603.7 ft (184 m) at 6 ft/hr (1.8 m/hr). The impreg's overall performance was 1,010 ft (308 m) at 5.2 ft/hr (1.6 m/hr), and the bit pulled out of hole in a very good condition. The solution enabled the operator to drill 200% further, more than the best offsets and saving multiple bit trips, which resulted in total savings of USD 195,000. This article will explain the benefits of the new technology and discuss how this novel impregnated bit successfully drilled the section in one run which is the first time ever to happen.
- Geology > Rock Type > Sedimentary Rock > Clastic Rock > Sandstone (0.38)
- Geology > Rock Type > Sedimentary Rock > Clastic Rock > Mudrock > Shale (0.37)
- Africa > Middle East > Tunisia > Hamra Basin (0.99)
- Africa > Middle East > Libya > Hamra Basin (0.99)
- Africa > Middle East > Algeria > Illizi Province > Illizi Basin (0.99)
- (3 more...)
Abstract This paper describes a detailed geochemical evaluation of the Paleozoic source rocks in the Chotts basin- Southern Tunisia. Cutting samples collected from Middle Ordovician Azzel Formation (Fm), Late Silurian-Early Devonian FegaguiraFm and Permian ZoumitFm were analysed using Rock-Eval pyrolysis, GC and GC/MS techniques. The FegaguiraFm is the principal petroleum source rock (SR) in the basin with Total Organic Carbon (TOC) values ranging from 1 to 20%. The Petroleum Potential (PP) and the Hydrogen Index (HI) values average 8 kg HC/t rock and 225 mg/g of TOC respectively indicate that the sediments have oil and gas generating potential. The terpanes series are dominated by the tricyclic and tetracyclic terpanes comparatively to hopanes with C23, C24 and C21 tricyclic terpane as prominent compounds. The diasterane contents are relatively high confirming the shaly character of the SR. The Azzel shales has poor to moderate, occasionally good, potential for sourcing oil and gas with TOC and PP values varying from 0.80 to 4.49 % and from 0.68 to 9.20 kg of HC/t rock respectively. The HI values of 95โ165 mg S2/g TOC and Tmax value of 435โ448ยฐC indicate mainly mature oil-prone kerogen. The biomarker features are characterized by high proportion of tricyclic terpanes that are dominated by C23 and C21 tricyclic terpanes. The hopanes fraction is dominated by C29 and C30 hopanes. The diasterane content are relatively high supporting the shaly character of the SR. The ZoumitFm shows fair to excellent TOC ranging from 0.06 to 6.84% and fair to good PP (reaching 4.77 kg of HC/t of rock) and both HI and Tmax values indicate mainly immature oil-prone kerogen. The biomarker analysis reveals a low content of trictyclic terpanes relative to pentacyclic terpanes. The content of C29 and C30 hopane is relatively high. The diasteranes are present in moderate to high proportions and are less abundant than regular steranes. These biomarker features indicate a marine OM associated with marly to argillaceous limestone SR, deposited in suboxic, normal salinity depositional environment.
- Phanerozoic > Paleozoic > Ordovician (1.00)
- Phanerozoic > Paleozoic > Permian (0.94)
- Geology > Geological Subdiscipline > Geochemistry (1.00)
- Geology > Geological Subdiscipline > Economic Geology > Petroleum Geology (1.00)
- Geology > Rock Type > Sedimentary Rock > Clastic Rock > Mudrock > Shale (0.73)
- Africa > Middle East > Tunisia > Central Tunisia > Chotts Basin (0.99)
- Africa > Middle East > Tunisia > Berkine Basin (Trias/Ghadames Basin) (0.99)
- Africa > Middle East > Libya > Berkine Basin (Trias/Ghadames Basin) (0.99)
- (2 more...)
Non-Radioactive Detectable Proppant First Applications in Algeria for Hydraulic Fracturing Treatments Optimization
Forno, Luca Dal (eni Algeria) | Latronico, Roberto (eni Algeria) | Saldungaray, Pedro (CARBO Ceramics) | Petteruti, Ernesto (eni Algeria) | Fragola, Daniele (eni Algeria) | Allal, Mohammed A. (Sonatrach) | Hachelaf, Houari (Sonatrach) | Albani, Danilo (eni Algeria) | Hamdane, Toufik (Sonatrach) | Carpineta, Gabriele (eni S.p.A)
Abstract Bir Rebaa Nord (BRN) and Bir Sif Fatima (BSF) fields, operated by Groupement Sonatrach-Agip (GSA, a JV between ENI and Sonatrach), are located in the Berkine basin in north-eastern Algeria. These fields are characterized by oil-bearing sandstone reservoirs with low to medium petro-physical properties. During the development phase, to counteract the effect of pressure depletion, water and gas injection was implemented for reservoir pressure maintenance. In addition, due to the increasing water cut, artificial lift systems were employed to effectively produce these fields. Hydraulic fracturing has been implemented in GSA since year 2000 to improve well performance, both in terms of productivity and injectivity for oil producers and water injectors respectively. The fracturing process has been improved over the years regarding operational procedures, enhanced reservoir knowledge and implementation of new technologies towards resolving the many uncovered challenges. Changes to the perforation strategy, fracturing fluids formulation, rock mechanics studies and design of proppant schedules are examples of enhancement to the fracturing practice that have been implemented in the recent years. One of the uncharted matters in GSA, coming out from the post-job data re-processing, was the necessity of a precise characterization of the hydraulic fractures vertical coverage. The presence of several sandstone layers with different properties brought questions if the fracture had grown into an unwanted zone or may had not properly covered the entire target formation. Moreover, fracture height is an essential parameter for frac models calibration. Its accurate determination drastically reduces the margin of error in treatment net pressure matching, helping to more precisely established fracture half-length and width, stress profile and, last but not least, achieving a calibrated model for future operations in the same area. This paper describes the successful implementation on two water injector wells of a novel non-radioactive detectable proppant for the first time in Algeria. The taggant material within the proppant has been located by comparing the pulsed neutron capture cased-hole logging passes registered before and after the hydraulic fracturing treatments. The detectable compound does not affect proppant properties and, in addition, its non-radioactive nature reduces the timing for materials delivery and eliminates the HSE risks linked to other tracing methods. The pulsed neutron measurements evaluation provided valuable information regarding fractures confinement, avoidance of contact with undesired layers and possible presence of cement channeling. Furthermore, combined with sonic logs and cores data, it helped refining the geo-mechanical model for future interventions design in the same reservoirs.
- Geology > Rock Type > Sedimentary Rock > Clastic Rock > Sandstone (1.00)
- Geology > Geological Subdiscipline > Geomechanics (1.00)
- Geophysics > Borehole Geophysics (1.00)
- Geophysics > Seismic Surveying > Passive Seismic Surveying > Microseismic Surveying (0.46)
- Africa > Middle East > Algeria > Eastern Algeria > Berkine Basin (Trias/Ghadames Basin) (0.99)
- Africa > Middle East > Algeria > Ouargla Province > Berkine Basin (Trias/Ghadames Basin) > Block 402a > Bir Sif Fatima Field > BSF-1 Well (0.94)
- Africa > Middle East > Algeria > Ouargla Province > Berkine Basin (Trias/Ghadames Basin) > Block 401a > Bir Sif Fatima Field > BSF-1 Well (0.94)