MOL (公司)

In the present study, a distinctive lineage of lymnaeid gastropods from the deep-water deposits of the Late Miocene Lake Pannon (Central Europe) is revised. The examined material includes specimens from museum collections as well as newly collected fossils from different parts of the Pannonian Basin System. During the past 150 years, at least 30 deep-water lymnaeid species assigned to ten genera have been described from the Lake Pannon deposits; however, our examination of more than 700 specimens shows that these records represent only 11 species belonging to five genera. Lectotypes are designated for four species for which earlier type designations were invalid. Species belonging to the Radix-Velutinopsis-Undulotheca-Provalenciennesia-Valenciennius lineage form one of the most extraordinary molluscan groups of Lake Pannon. Their interest lies in their distinctive shell morphology - large (sometimes exceeding 10 cm), wide, thin, cap-like shells with reduced coiling and undulated ribs - and their deep-water mode of life, supported by occurrences in drill cores and bathymetrically calibrated by seismic sections. This taxonomic revision enables the lineage to be applied in deep-water biostratigraphy of Lake Pannon sediments. Based on first appearance datums of key lineage species and associated taxa from other mollusc groups, four new lineage zones are proposed, integrated with the established deep-water mollusc biozonation. In contrast to the anagenetic evolutionary patterns typical of biostratigraphically important Lake Pannon bivalves, this gastropod lineage shows predominantly anacladogenetic speciation.

The extensional Neogene Pannonian Superbasin was superimposed on an Alpine, Cretaceous-Paleogene compressional realm which left a significant structural footprint in the pre-rift basement. Even though the surrounding Eastern Alps, Carpathians, and Dinarides project below the Pannonian Basin, even the existence of Alpine thrust-fold belts, including large nappes in the pre-rift basement of the Pannonian Basin has been debated until just a few decades ago. Based on the interpretation of primarily subsurface data sets, such as academic and industry reflection seismic and borehole data, the Cretaceous structural units of the Eastern Alps are correlated beneath the northwest Pannonian Basin with corresponding tectonic units of the Western Carpathians. Similarly, the Alpine folded belt beneath the southeast Pannonian Basin has a structural style very similar to the internal part of the Eastern and Southern Carpathians, specifically that of the Apuseni Mts. However, the level of understanding of the Eo- and Meso-Alpine thrust-fold belts beneath the Pannonian Basin system remains rudimentary compared to those known in the surrounding classical regions of the Eastern Alps, Carpathians and Dinarides. This mismatch is primarily caused by the subsurface nature of the problem and the pronounced overprint by Neogene transtensional tectonics.

In this study, we showcase a case examination, emphasizing the importance of dispersion crossover analysis from cross-dipole sonic data in a cased hole environment by using the slowness-frequency domain, utilizing two vertical wells drilled in the Tal block located in the northern region of Pakistan with highly complex geological conditions. Dispersion analysis is employed to distinguish the source of anisotropy by examining the fast and slow shear responses in low porosity Carbonates and Sandstone to identify fractures, their orientation, and the direction of maximum horizontal stress.

Abstract This paper presents strategies for drilling and managing salt within tectonically stressed regimes. Key challenges addressed include drilling multiple salt intervals using multicycle underreamers, casing re-orientation resulting from salt creep, and the role of salt as a natural barrier. Best practices are outlined through a case study involving a compromised 9-5/8" production casing cement job, where salt remained uncemented. Following the failure of the 9 5/8" cement job, a remedial operation was attempted; however, due to operational constraints, the salt interval remained uncemented. During subsequent RIH with the directional BHA, compression was observed (~20-30 klbs) at the upper boundary of the salt. Initial attempts to pass through the casing were unsuccessful, requiring POOH for re-evaluation. Although junk from a previously milled retainer was first suspected, detailed analysis confirmed that salt creep had re-oriented the casing. Ultrasonic logging was then performed to evaluate casing orientation, cement bonding, and formation contact. Based on these findings, flexible BHAs were deployed, successfully overcoming the challenge. Switching from stiffer bottom hole assemblies to more flexible configurations enabled smoother passage of the BHA through the wellbore, further confirming the influence of salt on casing orientation. It was concluded that, due to the 30-degree borehole inclination, the casing initially rested on the low side of the well; however, subsequent salt creep caused localized disorientation of the casing. Ultrasonic log evaluation supported this conclusion, identifying intervals of casing re-orientation consistent with salt movement. Minor variations in internal diameter were recorded, although the drift remained within acceptable limits, allowing safe passage of downhole tools. Once BHA was POOH no marks were observed on the BHA and the stabilizer gauges were the same (1/8" under gauge as initially)which confirmed that the issue was related to BHA stiffness rather than pass thru hinderance. Detailed analysis demonstrated that salt had crept upwards to the 9 5/8" casing and created a barrier or seal, which was evident from logging responses showing elevated acoustic impedance across the salt interval. This outcome had been anticipated, and the remedial plan for the 9 5/8" casing was accordingly designed with the top of cement deliberately positioned below the salt section to accommodate this behavior. Salt drilling across multiple streaks can be effectively managed using multicycle underreamers. This technique allows higher drilling parameters while reducing the likelihood of mechanical failure. Once salt sections are penetrated, the underreamers can be deactivated to mitigate risks such as arm loss or damage. The integration of flexible bottom hole assemblies, deliberate cement placement strategies, and careful underreamer utilization proved critical in maintaining wellbore stability and reducing risks associated with salt. This paper presents novel insights into managing salt drilling and its associated challenges. The findings provided valuable guidance for operators in Northern Pakistan and globally to better understand and mitigate the complexities of salt formations and successfully maneuvering through it. The case study also demonstrates the role of advanced ultrasonic evaluation in providing log-based confirmation of salt creeping and its subsequent effects on the casing shape and cementing. Additionally, the study highlights the potential of utilizing salt as a natural barrier, offering advantages for long-term well integrity and the first-time deployment of multicycle underreamers in Pakistan.

The majority of the world’s current crude oil production comes from mature fields. In addition, the rate of replenishment of reserves produced by new discoveries has been decreasing steadily over the past decades. This article provides a comprehensive overview of the status of CEOR and the opportunities for increasing ultimate recovery factors in reservoirs ranging from extra heavy oil to gas condensate. The review specifically discusses the status of CEOR and the chemicals used. Our aim in this work was to present both traditional and newer chemicals used. The relevant pilot tests were collected, because the literature on these is scarce. The published pilot projects are for the period after 2018. This article also describes chemical EOR opportunities, which also represent new CEOR drivers and challenges, especially economics. Recent CEOR technological developments and future CEOR opportunities will be discussed. State-of-the-art CEOR technologies were presented. This review provides comprehensive information on chemical EOR applications in sustainable energy production. After studying the professional publications, it is clear that CEOR technologies will be increasingly needed in the future.