The inhibition of growth by different concentrations of CdCl2 in the range 4,5 × 10−7 to 5.6 × 10−7M was studied in the green alga Coelastrum proboscideum Bohlin in inorganic media at pH 4.3, 5.3 and 6.2. The factorial destgn of the experiments was evaluated as an analysis of 22 factors. Below pH 4.0 and above pH 6.5 growth was depressed without adding Cd. Cd concentrations exceeding 5.6 × 10−8M reduced algal growth significantly with a 50% inhibition at 5.6 × 10−7M Cd. The Cd concentration of 5.6 × 10−7M was less toxic at pH 6.2 than at pH 5.3 and 4.3, thus revealing a negative interaction between protons and Cd.
T his second part of an article about a large 3D VSP survey in Abu Dhabi describes the interpretation effort which quantifies the value that a 3D VSP seismic image can bring when supplementing even a 640-fold, highresolution surface seismic volume.It is understood that for recovery to be optimized and bypassed resources to be minimized, especially in later stages of field production, more accurate models of a reservoir's architecture and characteristics are needed. This first 3D VSP survey in Abu Dhabi characterized details of the reservoir that could not be derived from surface data or well-log data alone. The higher-quality, higher-resolution images made it possible to map detailed stratigraphy and important but previously unknown faults. The improved structural map and updated geologic model were verified by wells drilled inside the 3D VSP image areas.
The effect of receiver array length and source effort on VSP qualityTo better understand the value in acquiring 3D VSP data with long borehole receiver arrays, processing tests using a conventional 12-level receiver configuration were conducted by using a subset of the 126-level VSP data. Using the same statics, velocity model, and other relevant processing parameters developed for the 126-level array data, a 3D VSP image was produced with data from only 12 geophone levels. Figure 1 compares VSP common depth point (VCDP) gathers at different offsets between the 12-and 126-level data. At an offset of 400 m, both the 12-and 126-level gathers show well organized energy from primary events. Good VSP images up to 400 m away from the well should be possible with both data sets. At the longer offset of 700 m, there does not appear to be any indication of primary events on the 12-level gather. However, due to higher fold, primary events are clearly visible on the 126-level gather. This result suggests the reason; in 12-level walkaway VSPs, it is difficult to image distances greater than 500 m from the wellbore, even though offsets up to 4 km
Abu Dhabi Company for Onshore Oil Operations (ADCO) undertook a two-well 3D VSP pilot project in 2007. Because it was acquired concurrently with a high-resolution wide-azimuth surface seismic survey, it was at the time the largest 3D VSP ever recorded. The project consisted of four main parts: acquisition, processing, interpretation, and quantifying value. In part 1 of this paper the acquisition and processing of the 3D VSP is described with an emphasis on the lessons learned. Significant advances in processing are described that demonstrate how larger 3D VSP images with better amplitudes and structural preservation can be produced. In part 2, the results of the 3D VSP interpretation and economic evaluation effort are described and illustrate different ways that a VSP image can help characterize a hydrocarbon reservoir.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.