Insight on the Exploration Potential of the Ordovician Gas Play in Tunisia Ghadames Basin, North Africa

Troudi, H.; Chevalier, Francis; Alouani, Wael; Mzoughi, Wala; Abdelkader, Omri

doi:10.2118/192634-ms

Cited by 3 publications

(2 citation statements)

References 6 publications

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“…Variscan shortening in North Africa (Simancas et al., 2005) resulted in a series of exposed (e.g., the Anti‐Atlas of Morocco and the Gargaf Arch, Figure 1, (Eschard et al., 2010)) or buried (e.g., the Tibetsi Arch of Libya and the Telemzane Arch, Figure 1), anticlinal structures, generally called “arches,” “highs” or “uplifts.” These arches are in the order of 100s of km long and 10s of km wide and are variably oriented at the regional scale. The area of work includes one of those geological structure buried under the Mesozoic and Cenozoic cover, named the Telemzane Arch ((Acheche et al., 2001; Soua, 2013; Troudi et al., 2018), Figure 1). While various authors have different opinions as to the geometry and age of the structure, it is generally assumed that the Telemzane Arch runs roughly in E‐W direction from Algeria to Libya.…”

Section: The Southern Chotts‐jeffara Basinmentioning

confidence: 99%

“…These arches are in the order of 100s of km long and 10s of km wide and are variably oriented at the regional scale. The area of work includes one of those geological structure buried under the Mesozoic and Cenozoic cover, named the Telemzane Arch ( (Acheche et al, 2001;Soua, 2013;Troudi et al, 2018), Figure 1). While various authors have different opinions as to the geometry and age of the structure, it is generally assumed that the Telemzane Arch runs roughly in E-W direction from Algeria to Libya.…”

Section: Tectonic Evolutionmentioning

confidence: 99%

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Architecture and Evolution of the Southern Chotts‐Jeffara Basin, Tunisia

Bruna,

Bertotti,

Charton

et al. 2023

Tectonics

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Southern Tunisia is known to be less deformed and simpler than its neighboring Atlassic domain to the north. This area is complex and basin evolution in the Southern Chotts‐Jeffara (SCJ) basin is debated. In this paper we combined surface and subsurface data with low temperature thermochronology (LTT) to reinvestigate the tectono‐sedimentary evolution of the SCJ basin from Permian to Jurassic. We reconstruct the present‐day architecture of the SCJ basin along two regional sections. In these sections, we focused mainly on regional thickness variations and on internal reflections interpreted from seismic data. We observe three structural elements: (a) A Paleozoic culmination, oriented E‐W, capped by Mid‐Upper Triassic deposits; (b) the Tebaga of Medenine (ToM), a culmination also oriented E‐W but located ∼50 km north of the Paleozoic culmination; and (c) A Triassic culmination in the eastern part of the area, oriented NW‐SE. We note the absence of major normal faults along the sections. The LTT data we present are the first published in this area and allow to reconstruct the timing and magnitude of vertical movements. These data prove: (a) exhumation at ∼230 Ma of the Permian and Lower Triassic units associated with the onset of the ToM removing locally about 900 m of pre‐Cretaceous sediments; and (b) the development of the Triassic culmination ∼180 Ma removing 2000 m of pre‐Cretaceous sediments in the Jebel Rehach. This study demonstrates that vertical movements in the SCJ basin are controlled by long‐wavelength processes developed essentially in shortening regimes.

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Section: The Southern Chotts‐jeffara Basinmentioning

confidence: 99%

Section: Tectonic Evolutionmentioning

confidence: 99%

Architecture and Evolution of the Southern Chotts‐Jeffara Basin, Tunisia

Bruna,

Bertotti,

Charton

et al. 2023

Tectonics

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Fracture distribution along open folds in southern Tunisia: implications for naturally fractured reservoirs

Smith,

Bruna,

Nasri

et al. 2023

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Fracture networks play a critical role in fluid flow within reservoirs, and it is therefore important to understand the interactions and influences of these networks. Our study focuses on the Southern Chotts–Jeffara Basin, which hosts reservoirs within Triassic, Permian and Ordovician units containing significant hydrocarbon accumulations. Recent developments on the structural understanding of the basin have proved that a regional shortening phase occurred between the Permian and Jurassic, forming open folds and a distributed fracture network. Analysis of late Paleozoic and Mesozoic outcrops within the basin has identified several sets of fractures (with dip directions and dip angles of 150/80 and 212/86) and compressional structural features that support this shortening hypothesis. We have integrated fracture data from surface analogues and subsurface analysis of advanced seismic attributes and well data through structural linking to form a 2D hybrid fracture model of the reservoirs in the region. Through analytical aperture modelling and numerical simulation, we found that the fractures orientated 212° in combination with large-scale fractures contribute significantly to the fluid-flow orientation and potential reservoir permeability. Our presented fracture workflow and framework provide an insight into network characterization within naturally fractured reservoirs of Tunisia, and how certain structures form fluid pathways that influence flow and production. Supplementary material: Data and figures detailing fracture characterisation and modelling along open folds in southern Tunisia are available at https://doi.org/10.6084/m9.figshare.c.6904499

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Increasing Production and Reserves Through Fracture Stimulation in Challenging, Multi-Zone, Vertical Well Completions

Boucher,

Shaoul,

Tkachuk

et al. 2023

Day 3 Thu, September 14, 2023

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The oilfield is scattered with wells that did not initially require fracture stimulation for economic production but could now benefit from hydraulic fracturing to improve well performance, increase reserves and accelerate production. Many of these wells are producing from multiple perforated intervals through completions with production tubing that were not designed for fracturing and cannot be worked over. This paper is a case study of a North African oil field producing from two Ordovician sands, one with a higher permeability (5 mD) and one with a much lower permeability (0.5 mD), where significant benefit was achieved by fracture stimulating one or both intervals in two wells, despite completion and operational limitations. The design of the fracture treatments and the methods used to try to achieve stimulation of the selected intervals are discussed in detail. Pre-fracture well test, PLT and production history data were all used to history match the pre-frac production using reservoir simulation modeling, to determine which intervals were contributing and to estimate the kh of each interval. Fracture design models were made using these results and different scenarios were evaluated, including the possibilityto cover both intervals with a single fracture and the effect on fracture placement of different fracture initiation locations. Contingencies were developed based on these fracture design simulations to use degradable diverting materials and proppant plugs if needed. Post-fracture production, well test and PLT results were analyzed to determine the fracture properties, the connected kh and if all stimulation objectives were met. In the first well, by-passing a high skin in the lower interval was the primary goal, but both intervals would benefit from fracture stimulation. The treatment had to be pumped down tubing and performed in a single operation. Temperature logging after the minifrac showed that both intervals were broken down and could be treated with a single large, propped fracture treatment, avoiding the use of mechanical diversion. In the second well, only the tighter upper interval was targeted, but a tubing completion with a slotted liner across the target interval made zonal isolation of the lower interval challenging. In both cases, results were above expectations and showed a stimulation of both the targeted intervals and an increase in the connected kh compared to log and well test data. This is common in fracturing of layered heterogeneous reservoirs, where a perforated completion does not contact all the potential thin pay layers. This paper describes real-world success stories of fracturing with multiple intervals open through an existing completion that is not designed for fracturing. It highlights the potential for fracturing in many existing reservoirs to improve productivity, increase reserves and improve acceleration, without having to recomplete the well.

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Insight on the Exploration Potential of the Ordovician Gas Play in Tunisia Ghadames Basin, North Africa

Cited by 3 publications

References 6 publications

Architecture and Evolution of the Southern Chotts‐Jeffara Basin, Tunisia

Architecture and Evolution of the Southern Chotts‐Jeffara Basin, Tunisia

Fracture distribution along open folds in southern Tunisia: implications for naturally fractured reservoirs

Increasing Production and Reserves Through Fracture Stimulation in Challenging, Multi-Zone, Vertical Well Completions

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