A QSAR-like analysis of the adsorption of endocrine disrupting compounds, pharmaceuticals, and personal care products on modified activated carbons

Rapid small-scale column tests (RSSCTs) examined the removal of 29 endocrine disrupting compounds (EDCs) and pharmaceutical/personal care products (PPCPs). The RSSCTs employed three lignite variants: HYDRODARCO 4000 (HD4000), steam-modified HD4000, and methane/steam-modified HD4000. RSSCTs used native Lake Mead, NV water spiked with 100–200 ppt each of 29 EDCs/PPCPs. For the steam and methane/steam variants, breakthrough occurred at 14,000–92,000 bed volumes (BV); and this was 3–4 times more bed volumes than for HD4000. Most EDC/PPCP bed life data were describable by a normalized quantitative structure–activity relationship (i.e. QSAR-like model) of the form:

where TPV is the pore volume, ρ_mc is the apparent density, CV is the molecular volume, C_o is the concentration, ⁸χ_p depicts the molecule's compactness, and FOSA is the molecule's hydrophobic surface area.     

Constraining the stress tensor in the Visund field, Norwegian North Sea: Application to wellbore stability and sand production

In this study we examine drilling-induced tensile wellbore failures in five exploration wells in the Visund oil field in the northern North Sea. We use observations of drilling-induced wellbore failures as well as density, pore pressure, and leak-off test measurements to estimate the magnitudes and orientations of all three principal stresses. Each well yields a very consistent azimuth of the maximum horizontal stress (100°±10°), both with depth and laterally across the field. Stress orientations are constrained at depths as shallow as 2500 m and as deep as 5300 m in these wells. We show that the magnitudes of the three principal stresses (S_v, S_hmin, and S_Hmax) are also consistent with depth and reflect a strike-slip to reverse faulting stress regime. The magnitude of the maximum horizontal stress is shown to be significantly higher than the vertical and minimum horizontal stresses (e.g. S_v=55 MPa, S_hmin=53 MPa, and S_Hmax=71.5 MPa at 2.8 km depth). Data from earthquake focal plane mechanisms (Lindholm et al., 1995, Proceedings of the Workshop on Rock Stresses in the North Sea, Trondheim, Norway [1]) show similar stress orientations and relative magnitudes and thus indicate a stress field that is relatively consistent throughout the thickness of the brittle crust.We illustrate how knowledge of the full stress tensor allows one to place bounds on in situ rock strength and determine optimally stable trajectories for wellbore stability and sand production during drilling, after the completion of drilling, and as pore pressure is reduced during oil and gas production.     

Orientation and magnitude of in situ stress to 6.5 km depth in the Baltic Shield

Understanding the state of stress in the earth is important for a broad range of engineering and geological problems. To obtain the state of stress in boreholes where conditions are such that conventional stress measurement techniques are impossible, we have used recent developments in the analysis of compressive and tensile wellbore failure in an integrated stress measurement strategy, involving also direct measurement of the least principal stress. The analysis is carried out in the two deep boreholes in the Siljan Ring area of the Baltic Shield. The Gravberg-1 borehole reached 6779 m true vertical depth (TVD) in the Siljan region, central Sweden, and the Stenberg-1 borehole, drilled 10 km to the south of Gravberg-1, was completed at 6529 m TVD. Analysis of vertical, drilling-induced tensile fractures in the nondeviating part of the Gravberg-1 well indicated that one principal stress is vertical and thus could be calculated from density estimates. Borehole breakouts and tensile fractures indicated that the average direction of the maximum horizontal stress, S_H, is N72°W±7° in Gravberg-1 and N53°W±9° in the Stenberg-1 well. The direction of S_H is on average very stable in both wells. Lower bound limits on the magnitude of the minimum horizontal stress, S_h, in the Gravberg-1 well were obtained from controlled and uncontrolled hydraulic fracturing and formation integrity tests. At 5 km depth in the Gravberg-1 borehole the minimum horizontal stress is approximately two-thirds of the vertical stress. We estimated the magnitude of the maximum horizontal stress in Gravberg-1 on the basis of drilling-induced tensile fractures identified in the borehole. S_H was estimated by calculating the stress at the borehole wall necessary to cause tensile failure of the formation, incorporating our lower bound S_h estimates, corrections for the cooling of the wellbore by drilling fluids and differential fluid pressures. Our results indicate a strike-slip faulting regime in the Siljan area and that the state of stress is in frictional equilibrium with a coefficient of friction in the range 0.5 to 0.6.     

Brazilian test: stress field and tensile strength of anisotropic rocks using an analytical solution

Tensile strength of rock is among the most important parameters influencing rock deformability, rock crushing and blasting results. To calculate the tensile strength from the indirect tensile (Brazilian) test, one must know the principal tensile stress, in particular at the rock disc center, where a crack initiates. This stress can be assessed by an analytical solution. A study of this solution for anisotropic (transversely isotropic) rock is presented.

The solution is given explicitly. The key expansion coefficients are obtained from a complex-valued 2×2 matrix equation. The convergence of the solution is greatly improved by a new procedure. It is shown that the dimensionless stress field depends only on two intrinsic parameters, E′/E and b. The stress at the center of the disc is given in charts as a function of these parameters (and the angle θ_b between the direction of applied force and the plane of transverse isotropy). Furthermore, a new, reasonably accurate, approximate formula for the principal tension at the disc center, (0,0), is derived from the analytical solution:

where

The elastic parameters of rock in two perpendicular directions were measured in the laboratory. The result of the stress analysis was applied in calculating the indirect tensile strength of gneiss, which has a well-defined foliation plane (transversely isotropic). When the results were compared with the tensile strength of rock obtained by using a conventional formula that assumes isotropic material, there was a significant difference. Moreover, good agreement was observed for the tensile strength calculated from the stress charts and the proposed formula, when compared with other published stress charts.     

Strategic Planning for Long-Term Flood Risk Management: Some Suggestions for Learning How to Make Strategy at Regional and Local Level

Often, discussions about improving long-term Flood Risk Management (FRM) refer to spatial planning as one of the most promising policy instruments (non-structural measures), especially after flood disasters like in Dresden in August 2002. However, up to now, evidence is limited that spatial planning is used intensively and systematically for long-term FRM, for instance, to reduce vulnerability in flood-prone areas by controlling developments on floodplains and providing development possibilities in non-hazardous areas (Burby et al., 2000 Burby, R. J., Deyle, R. E., Godschalk, D. R. and Olshansky, R. B. 2000. Creating hazard resilient communities through land-use planning. Natural Hazards Review, 1(2): 99–106. [Crossref] [Google Scholar]). Based on the literature on strategic spatial planning (e.g., Albrechts, 2004a Albrechts, L. 2004a. Strategic (spatial) planning re-examined. Environment and Planning B: Planning and Design, 31: 743–758. [Crossref], [Web of Science ®] [Google Scholar]; Bryson, 2004 Bryson, J. M. 2004. “Strategic planning for public and nonprofit organizations.”. In A Guide to Strengthening and Sustaining Organizational Achievement, San Francisco: Jossey-Bass.  [Google Scholar]; Healey, 2007 Healey, P. 2007. “Urban complexity and spatial strategies”. In Towards a Relational Planning for Our Times, London: Routledge.  [Google Scholar]) and risk management (e.g., Klinke & Renn, 2002 Klinke, A. and Renn, O. 2002. A new approach to risk evaluation and management: risk-based, precaution-based, and discourse-based strategies. Risk Analysis, 22(6): 1071–1094. [Crossref], [PubMed], [Web of Science ®] [Google Scholar]), this paper presents normative conclusions from case studies conducted in Dresden and London on how to use strategic planning for improving long-term FRM.

The twin hazards of uncertainty and disagreement form an essential context for plannin?s ambitions of shaping the future. In practice, planners may retreat to shorter-range decisions with more limited consequences. Or they may resort to public relations devices that may gain agreement in superficial ways. Still another response is to hide behind technical analyses that are not fully shared with the public, neither revealing the true level of uncertainty nor exposing judgements to potential disagreements. Better methods are clearly desired for professional leadership regarding the future.

(Myers, 2001 Myers, D. 2001. Symposium: putting the future in planning. Introduction. JAPA: Journal of the American Planning Association, 67(4): 365–367. [Taylor & Francis Online], [Web of Science ®] [Google Scholar]: 365)

Transverse drilling-induced tensile fractures in the West Tuna area, Gippsland Basin, Australia: implications for the in situ stress regime

Drilling-induced tensile fractures (DITFs) have been interpreted on image logs from vertical wells in the Gippsland Basin, offshore southeastern Australia. Interpreted axial (vertical) DITFs have previously been well described worldwide. We also interpret transverse (horizontal) DITFs, which are horizontal fractures that are electrically conductive, non-planar, bimodal and constrained to the tensile region of the wellbore.Elasticity theory predicts formation of both transverse and axial drilling-induced tensile fractures (DITFs) in vertical wells depending on the magnitude of the principal in situ stresses, pore-pressure and mudweight. Drilling-induced tensile fractures initiate in very specific stress environments. Axial DITFs can closely constrain a lower bound to the maximum horizontal stress (S_H max) magnitude where the minimum horizontal (S_h min) stress is known. If transverse DITFs are observed, they can constrain a lower bound to maximum and minimum horizontal stress magnitudes. The observation of transverse DITFs on image logs can constrain the stress field to one on the border of strike-slip and reverse faulting () without requiring knowledge of the S_h min or S_H max magnitude. The observation of transverse DITFs in the West Tuna area combined with wireline log data, leak-off tests and pore pressure data are used to constrain the in situ stress tensor. The interpreted in situ stress tensor lies on the border of a strike-slip and reverse faulting regime (S_H max40.5 MPa/km>S_h min≈S_v21 MPa/km). Interpreted data from leak-off tests in the West Tuna area confirm that S_h minS_v.