Integration Success Story in Shilaif Shale Oil from Vertical Pilot to Horizontal

The development of unconventional target in the Shilaif formation is in line with the Unconventional objective towards adding to ADNOC reserves. For future optimization of development plans, it is of utmost importance to understand and test and therefore prove the productivity of the future Unconventional Horizontal Oil wells. The Shilaif formation was deposited in a deeper water intrashelf basin with thicknesses varying from 600 to 800 ft from deep basin to slope respectively. The formation is subdivided into 3 main composite sequences each with separate source and clean tight carbonates. The well under consideration (Well A-V for the vertical pilot and Well A-H for the horizontal wellbore) was drilled on purpose in a deep synclinal area to access the best possible oil generation and maturity in these shale Oil plays. Due to the stacked nature of these thick high-quality reservoirs, a pilot well is drilled to perform reservoir characterization and test hydrocarbon type and potential from each bench. Fracturing and testing are performed in each reservoir layer for the primary purpose to evaluate and collect key fracturing and reservoir parameter required to calibrate petrophysical and geomechanical model, landing target optimization and ultimately for the design of the development plan of this stacked play. Frac height, reservoir fluid composition and deliverability, pore pressure are among key data collected. The landing point selected based on the comprehensive unconventional core analysis integrated with petrophysical and geomechanical outcomes using post vertical frac and test results. Well A-H was drilled as a sidetrack from the pilot hole Well A-V. This lateral section was logged with LWD Triple Combo while Resistivity Image was acquired on WL. Based on the logging data the well stayed in the target Layer / formation, cutting analysis data for XRD and TOC was integrated with the petrophysical results in A-H well. Production test results from subject were among the highest rate seen during exploration and appraisal of this unconventional oil plays and compete with the current commercial top tier analog unconventional oil plays. Achieving those results in such early exploration phases is huge milestone for ADNOC unconventional exploration journey in UAE and sign of promising future development.

Depositional Model for Turbidite Lobes in Complex Slope Settings Along Transform Margins: The Motta San Giovanni Formation (Miocene—Calabria, Italy)

Intraslope lobes, or perched lobes, are attracting scientific interest because they represent a key archive between the shelf and the deep basin plain when looking at a complete source-to-sink depositional system across a continental margin and can form significant offshore hydrocarbon plays. In this study, we focus on a detailed characterization of intraslope lobes of the Motta San Giovanni Formation (Miocene, Calabria), which were deposited in confined conditions during the Miocene along a transform margin. We determine the typical facies associations and stratigraphic architecture of these intraslope lobes using a 3D digital outcrop model resulting from a combined Uncrewed Aerial Vehicle (UAV) and walking acquisition, together with sedimentological logging and geological mapping. We propose recognition criteria for the identification of intraslope lobes, including facies and geometries, integrated within a depositional model. A comparison with other well-known intraslope and confined lobes, as well as basin floor lobes, is finally discussed, to highlight the peculiarities of intraslope lobes deposited along transform margins. The diagnostic depositional model for these types of intraslope lobes includes four main stages of evolution: 1) Stage 1—isolated detached lobe precursor in response to a flushed hydraulic jump, 2) Stage 2—prograding and aggrading lobe elements associated with a relatively stable and submerged hydraulic jump in the Channel-Lobe Transition Zone (CLTZ), 3) Stage 3—major bypass associated with lateral accretion and local aggradation interpreted as a renewal of a normal hydraulic jump in the CTLZ, and 4) Stage 4—erosion and bypass then abandonment. The development of intraslope lobes along active transform margins is allowed by tectonically induced slope segmentation and local confinement. In such a context, flow stripping and overspill processes occurred. Resulting lobes appear to be particularly small and relatively thin sandy deposits. They could be considered end-member in a lobe classification based on the Net-to-Gross content (high) and taking into account their thickness/width ratio (intermediate between 10:1 and 100:1 lines).

Analysis of Geologic CO2 Migration Pathways in Farnsworth Field, NW Anadarko Basin

This study reports on analyses of natural, geologic CO2 migration paths in Farnsworth Oil Field, northern Texas, where CO2 was injected into the Pennsylvanian Morrow B reservoir as part of enhanced oil recovery and carbon sequestration efforts. We interpret 2D and 3D seismic reflection datasets of the study site, which is located on the western flank of the Anadarko basin, and compare our seismic interpretations with results from a tracer study. Petroleum system models are developed to understand the petroleum system and petroleum- and CO2-migration pathways. We find no evidence of seismically resolvable faults in Farnsworth Field, but interpret a karst structure, erosional structures, and incised valleys. These interpretations are compared with results of a Morrow B well-to-well tracer study that suggests that inter-well flow is up-dip or lateral. Southeastward fluid flow is inhibited by dip direction, thinning, and draping of the Morrow B reservoir over a deeper, eroded formation. Petroleum system models predict a deep basin-ward increase in temperature and maturation of the source rocks. In the northwestern Anadarko Basin, petroleum migration was generally up-dip with local exceptions; the Morrow B sandstone was likely charged by formations both below and overlying the reservoir rock. Based on this analysis, we conclude that CO2 escape in Farnsworth Field via geologic pathways such as tectonic faults is unlikely. Abandoned or aged wellbores remain a risk for CO2 escape from the reservoir formation and deserve further monitoring and research.

Application of Empirical Bathymetry Method on Sentinel 2A for Measuring Water Depth of Maninjau Lake

Lake Maninjau is a lake formed by volcanic activity. Many human activities occur on the catchment area, but also in exploited waters. This study aims to mapping the depth of the waters in the Lake Maninjau and assess the effect of field sample distribution on the quality results of the image transformation. The data used are satellite imagery Sentinel 2A, results of point survey. The analysis technique uses the normalized difference water index algorithm, sun glint, empirical bathymetry method and linear regression. The result of the research which is has found that variations of distribution into the dispersion of the recording process of the depth of the object represented by cell. The depth of the water from the results of this transformation refers to the measurement sample in the field survey. The maximum depth of the waters is in the range of 107m. Shallow waters are predominantly distributed in the northern region which is the out late of Lake Maninjau. The southern area forms a deep basin. The distribution of this sample is in the form of an empirical bathymetry map and the relationship between the results of field measurements and the transformation with a regression value of 0.769, this indicates the consideration of total and distribution of survey sample is influence on quality of the results of the transformation.

Systematic Build-Up Pressure Analysis Advances Accurate Fingerprinting of Formation Breathing in Gas Wells

Differentiating wellbore breathing from real influxes in Alberta's Deep Basin has been problematic in the past as they both result in similar surface parameters. An incorrect interpretation of formation breathing may lead to significant non-productive time (NPT) as secondary well control operations from an influx can take days. On the contrary, a false negative will force drillers to perform secondary well control procedures that may lead to loss of circulation if excessive and unnecessary pressure is exerted on the formation. MPD allows for a systematic approach to identify wellbore breathing more accurately in gas wells. The process involves a series of consecutive pressure build-up and flowback tests with close real-time monitoring to identify a breathing formation that is returning fluid to surface as microfractures close. This paper describes the protocol designed for distinguishing wellbore breathing and illustrates how several drilling parameter trends were interpreted to correctly identify wellbore breathing characteristics and differentiate them from a migrating gas influx. Testing the procedure on multiple wells resulted in 70% operational time savings from reduction in post mud rollover delays on breathing wellbores. This paper shows that the methodology utilized provides consistent and effective results using the MPD techniques, eliminates the ambiguity of wellbore breathing versus actual influxes, and shows the potential application in more areas that are prone to this problem, reducing uncertainty, NPT, and total drilling time.

Gravimetry and petrophysics for defining the intracratonic and rift basins of the western-central Africa zone.

The global gravity field obtained from the observations of the satellite GOCE offers new opportunities in defining density variations of Earth’s crust and mantle, allowing new insights into the structure of specific geologic features. The central African rift is a key feature in understanding of the dismemberment of Gondwana, and we contribute to defining the crustal density structure underlying the rift. The presence of a narrow and up to 12 km deep basin implies crustal stretching to allow the sediment to accumulate, but a key question is whether the stretching processes affected also the deeper layers of the crust or was limited to the upper crust. The study-area includes a sub-basin of the greater Chad sag-basin, which extends over a 1500 km by 1500 km, and occupies the center of North-Central Africa, shared between the countries of Chad, Sudan, Nigeria, Niger, Algeria, Libya and Cameroon. We find that the rifting affected the lower crust of the West African Rift and demonstrate evidence for a 1500 km long and several km thick magmatic crustal intrusion presumably associated with underplating and crustal thinning. We estimate that the stretching factor must be at least 1.5 and had affected the entire crust. To our knowledge, the identification of a continuous body of magmatic intrusions is new and has been only possible through the recent global gravity field. The magmatism has altered the thermal conditions from the time of emplacement on, and is relevant for the maturation of hydrocarbons present in the sediments. The timing of the magmatism is presumably tied to two pulses of volcanism documented in the rift, associated with the first post-rift phase from 96 to 88 Ma and the second post-rift phase from 23 Ma up to the Quaternary.

A fjord-like tropical ecosystem, Pacific coast of Costa Rica: overview of research in Golfo Dulce

Introduction: Coastal ecosystems worldwide are under the influence of local, regional and global stressors, such as pollution, eutrophication and climate change. Golfo Dulce is a relatively pristine and accessible deep tropical ecosystem that provides opportunities for comparative and collaborative research. Objective: To summarize published reports on past research conducted in this ecosystem, identify topics for further study, and suggest new research issues. Methods: A search was made on the web for reports based on research conducted in Golfo Dulce and published in scientific journals. Reports focusing on environmental parameters and on the biota were included. Results: A total of 123 studies that include data from Golfo Dulce are cited. The four topics more frequently addressed were reports based on the results of the R/V Victor Hensen expedition (1993-1994) and follow-up work on microbiology, studies on water parameters, research on vertebrates, and zooplankton studies. The reports focusing on vertical profiles of oxygen and temperature are discussed in detail, followed by those on the biota. Conclusions: Golfo Dulce has low oxygen concentrations below 50 m and is frequently anoxic at the 200 m deep basin with occasional formation of H2S. However, the ecosystem contains a relatively high diversity of identified organisms, from bacteria to whales. Of particular relevance for future studies are multidisciplinary surveys aiming at obtaining data on primary productivity, the diversity and biomass of the main groups of planktonic, demersal and benthic organisms, and the frequency and magnitude of the influx of deep offshore waters over the sill into the basin. These data, as well as the information gathered in the past, are essential for updating the trophic model developed more than 25 years ago and in support of new predictive models on the functioning of the ecosystem.