Fracture characterization of Asmari Formation carbonate reservoirs in G Oilfield, Zagros Basin, Middle East
The Asmari Formation in the G oilfield on the Iran-Iraq border is a fractured-porous multi-lithology mixed reservoir, for which fracture is an important factor affecting oil productivity and water cut. The characterization and modeling of fractures in the carbonate reservoir of G oilfield are challe...
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| Format: | Article |
| Language: | English |
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KeAi Communications Co., Ltd.
2023-07-01
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| Series: | Energy Geoscience |
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| Online Access: | http://www.sciencedirect.com/science/article/pii/S2666759223000240 |
| _version_ | 1797798590109712384 |
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| author | Kaijun Tong Juan He Shaoqun Dong Futing Sun Peiyuan Chen Yi Tong |
| author_facet | Kaijun Tong Juan He Shaoqun Dong Futing Sun Peiyuan Chen Yi Tong |
| author_sort | Kaijun Tong |
| collection | DOAJ |
| description | The Asmari Formation in the G oilfield on the Iran-Iraq border is a fractured-porous multi-lithology mixed reservoir, for which fracture is an important factor affecting oil productivity and water cut. The characterization and modeling of fractures in the carbonate reservoir of G oilfield are challenging due to weak conventional well log responses of fractures and a lack of specific logs, such as image logs. This study proposes an integrated approach for characterizing and modeling fractures in the carbonate reservoir. The features, formation mechanism, influencing factors, and prediction methods of fractures in the Asmari Formation carbonate reservoirs of G oilfield were studied using core observation, thin section, image log, cross-dipole acoustic log (CDAL), geomechanics numerical simulation (GNS), and production data. According to CDAL-based fracture density interpretation, GNS-based fracture intensity prediction between wells, and DFN-based rock fracture properties modeling, the quantitative fracture characterization for G oilfield was realized. This research shows that the fractures in the Asamri Formation are mainly medium-to high-angle shear fractures. The substantial compression stress during the Miocene played a major role in the formation of the prominent fractures and determined their trend in the region, with primary trends of NNW-SSE and NNE-SSW. The fracture distribution has regularity, and the fractures in zone A dolomites are more highly developed than that in zone B limestones vertically. Horizontally, fractures intensity is mainly controlled by faults and structural location. The results of this study may benefit the optimization of well design during field development. From 2019 to 2021, three horizontal wells pilot tests were deployed in the fractures belt in zone A, and these fractures prominently increased the permeability of tight dolomite reservoirs. The initial production of the wells is four to five times the average production of other wells in the area, showing a good development effect. Meanwhile, the updated numerical simulation validates that the history match accuracy of water cut based on the dual-porosity model is significantly improved, proving the fracture evaluation and prediction results to be relatively reliable and applicable. |
| first_indexed | 2024-03-13T04:06:06Z |
| format | Article |
| id | doaj.art-367882e78a0b41a1a6db4933f6440899 |
| institution | Directory Open Access Journal |
| issn | 2666-7592 |
| language | English |
| last_indexed | 2024-03-13T04:06:06Z |
| publishDate | 2023-07-01 |
| publisher | KeAi Communications Co., Ltd. |
| record_format | Article |
| series | Energy Geoscience |
| spelling | doaj.art-367882e78a0b41a1a6db4933f64408992023-06-21T07:00:58ZengKeAi Communications Co., Ltd.Energy Geoscience2666-75922023-07-0143100178Fracture characterization of Asmari Formation carbonate reservoirs in G Oilfield, Zagros Basin, Middle EastKaijun Tong0Juan He1Shaoqun Dong2Futing Sun3Peiyuan Chen4Yi Tong5CNOOC International Ltd, Beijing, 100028, China; Corresponding author.CNOOC International Ltd, Beijing, 100028, ChinaCollege of Science, China University of Petroleum, Beijing, 102249, ChinaCNOOC International Ltd, Beijing, 100028, ChinaCNOOC International Ltd, Beijing, 100028, ChinaCNOOC International Ltd, Beijing, 100028, ChinaThe Asmari Formation in the G oilfield on the Iran-Iraq border is a fractured-porous multi-lithology mixed reservoir, for which fracture is an important factor affecting oil productivity and water cut. The characterization and modeling of fractures in the carbonate reservoir of G oilfield are challenging due to weak conventional well log responses of fractures and a lack of specific logs, such as image logs. This study proposes an integrated approach for characterizing and modeling fractures in the carbonate reservoir. The features, formation mechanism, influencing factors, and prediction methods of fractures in the Asmari Formation carbonate reservoirs of G oilfield were studied using core observation, thin section, image log, cross-dipole acoustic log (CDAL), geomechanics numerical simulation (GNS), and production data. According to CDAL-based fracture density interpretation, GNS-based fracture intensity prediction between wells, and DFN-based rock fracture properties modeling, the quantitative fracture characterization for G oilfield was realized. This research shows that the fractures in the Asamri Formation are mainly medium-to high-angle shear fractures. The substantial compression stress during the Miocene played a major role in the formation of the prominent fractures and determined their trend in the region, with primary trends of NNW-SSE and NNE-SSW. The fracture distribution has regularity, and the fractures in zone A dolomites are more highly developed than that in zone B limestones vertically. Horizontally, fractures intensity is mainly controlled by faults and structural location. The results of this study may benefit the optimization of well design during field development. From 2019 to 2021, three horizontal wells pilot tests were deployed in the fractures belt in zone A, and these fractures prominently increased the permeability of tight dolomite reservoirs. The initial production of the wells is four to five times the average production of other wells in the area, showing a good development effect. Meanwhile, the updated numerical simulation validates that the history match accuracy of water cut based on the dual-porosity model is significantly improved, proving the fracture evaluation and prediction results to be relatively reliable and applicable.http://www.sciencedirect.com/science/article/pii/S2666759223000240Geomechanics numerical simulationDual-porosity modelCarbonate reservoirFracture densityAsmari FormationZagros Basin |
| spellingShingle | Kaijun Tong Juan He Shaoqun Dong Futing Sun Peiyuan Chen Yi Tong Fracture characterization of Asmari Formation carbonate reservoirs in G Oilfield, Zagros Basin, Middle East Energy Geoscience Geomechanics numerical simulation Dual-porosity model Carbonate reservoir Fracture density Asmari Formation Zagros Basin |
| title | Fracture characterization of Asmari Formation carbonate reservoirs in G Oilfield, Zagros Basin, Middle East |
| title_full | Fracture characterization of Asmari Formation carbonate reservoirs in G Oilfield, Zagros Basin, Middle East |
| title_fullStr | Fracture characterization of Asmari Formation carbonate reservoirs in G Oilfield, Zagros Basin, Middle East |
| title_full_unstemmed | Fracture characterization of Asmari Formation carbonate reservoirs in G Oilfield, Zagros Basin, Middle East |
| title_short | Fracture characterization of Asmari Formation carbonate reservoirs in G Oilfield, Zagros Basin, Middle East |
| title_sort | fracture characterization of asmari formation carbonate reservoirs in g oilfield zagros basin middle east |
| topic | Geomechanics numerical simulation Dual-porosity model Carbonate reservoir Fracture density Asmari Formation Zagros Basin |
| url | http://www.sciencedirect.com/science/article/pii/S2666759223000240 |
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