Understanding the scaling relation of damage zone width with displacement of faults is important for predicting subsurface faulting mechanisms and fluid flow processes. The understanding of this scaling relationship is influenced by the accuracy of the methods and types of data utilized to investigate faults. In this study, seismic reflection data are used to investigate the throw and damage zone width of five strike-slip faults affecting Ordovician carbonates of the Tarim intracraton basin, NW China. The results indicate that fault slips with a throw less than 200 m had formed wide damage zones up to 3000 m in width. Also, damage zone width is found to have both a positive correlation and a power-law relation with throw of two orders of magnitude, with a ratio of these values varying in a range of 2–15. The relationship between throw and damage zone width is not a simple power-law and changes its slope from small to larger size faults. The results indicate that throw scales well with damage zone width for the studied faults, and hence these can be used to predict fault geometries in the Tarim Basin. The study of the wide carbonate damage zones presented here provides new insights into scaling of large-size faults, which involve multiple faulting stages.

The largest ultra-deep (>6000 m) strike-slip fault-controlled oilfield in the world is found in the Tarim Basin of Northwestern China. The localized fractured reservoirs are the major production targets along the strike-slip fault zones. Different from its use in the primary porous-type reservoirs, however, the conventional technology is not favorable for use in oil/gas development in Ordovician carbonate reservoirs. For this reason, high-density seismic acquisition and high-resolution seismic processing were carried out to provide high-precision data for fault and fractured reservoir identification. In addition, the multi-filtering process and the maximum likelihood method are typically used to identify small faults and fault segments along a strike-slip fault zone. Further, seismic facies-constrained inversion and amplitude attributes are favorable for large fracture-cave reservoir description. With the advancements in seismic technology, the high and stable production well ratio has been doubled in the “sweet spots” of fractured reservoir optimization, and the first ultra-deep strike-slip fault-controlled oilfield with an annual oil production of over 1 million tons has been realized, achieving economic development in the ultra-deep fractured reservoirs. However, unstable production and high rates of production decline are still significant challenges in the economic exploitation of the ultra-deep fractured reservoirs. Seismic technology requires further improvement for the description of small fractured reservoirs and matrix reservoirs, as well as reservoir connectivity prediction and hydrocarbon detection in the deep subsurface.

A giant, ultra-deep (>7000 m) strike-slip fault-related oilfield has been found in the central depression of the Tarim Basin. However, little research has addressed this discovery to understand the fault effects on the oil migration, which constrains the oil exploitation deployment and well optimization. Based on fault modeling and fluid analysis, we present the effects of fault segment on the oil segmentation and migration in the ultra-deep Fuman Oilfield. The results show a distinct fault segmentation and also subsequent variable fault architecture and non-connected fracture network other than a through-going fault zone. There are fault segment-related isolated fractured reservoirs and fluid variation along the fault strike, which indicates that a large oilfield comprises a series of unconnected small oil reservoirs along the fault segments. The fluid segmentation and molecular indicator of dibenzothiophenes reveal that there is a variable petroleum lateral migration along the strike-slip fault segment. The fault segmentation is a major contribution in the varied oil accumulation along the strike-slip fault zone in Fuman Oilfield. This case study suggests that fault segmentation has variable effects on petroleum migration and accumulation along the strike-slip zone.

The identification of structural diagenesis and the reconstruction of diagenetic paragenesis in fault damage zones is important for understanding fault mechanisms and fluid flow in the subsurface. Based on the examination of core and sample thin section data, we deciphered the diagenetic parasequence and their fault controls for Ordovician carbonates in the northern Tarim intracratonic basin in NW China (Halahatang area). In contrast to the uniform nature of diagenesis observed in country rocks, there is a relatively complicated style of compaction and pressure solution, multiple fracturing, and cementation and dissolution history along the carbonate fault damage zones. The relative paragenetic sequence of the structure related diagenesis suggests three cycles of fracture activities, following varied fracture enlargement and dissolution, and progressively weaker calcite cementation. These processes of structure related diagenesis are constrained to the fault damage zones, and their variation is affected by the fault activities. The results of this study suggest that the carbonate reservoir and productivity could be impacted by the structure related diagenesis locally along the fault damage zones.