We have investigated cobaltite relatives of the layered perovskite cuprates and nickelates, Pr2−xCaxCoO4 (0.39 ≤ x ≤ 0.73) and La2−xSrxCoO4 (x = 0.61), using elastic neutron scattering. We have discovered doping-dependent incommensurate short-range ordering of charges and magnetic moments, which in cobaltites occur in the range of heavy doping, 0.5 x 0.75. The charge order exists already at room temperature and shows no change on cooling. The incommensurability of its propagation vector, Qc = (ǫc, 0, l), roughly scales with the concentration of Co 2+ ions, ǫc ∼ (1 − x). Magnetic order is only established at low T 40 K and has twice larger periodicity, indicating a dominant antiferromagnetic correlation between the nearest Co 2+ spins. Physical origins of the ubiquitous doping-dependent incommensurate charge and spin ordering (CO and SO) in doped La 2−x Sr x CuO 4 cuprates and their relevance to mechanisms of the high-temperature superconductivity have been subjects of intense research for more than a decade but still remain a mystery. Numerous experimental studies have shown, that holes in weakly doped cuprates exhibit an in-plane CO, whose propagation vector scales roughly proportionally with doping x and magnetic order, whose modulation period is twice larger [1,2,3]. Similar findings were reported in closely related, isostructural but insulating layered perovskite nickelates La 2−x Sr x NiO 4 [4,5,6,7,8]. A simple picture of the simultaneous real-space static ordering of charges and spins yielding such CO and SO is provided by the charge stripe model, where doped holes segregate into lines separating stripes of antiferromagnetically ordered domains [1].The charge stripe picture is strongly supported by theoretical analysis of the two-dimensional (2D) Hubbard model, which is believed to describe high-T c cuprates [3,9,10,11,12]. In the 2D Hubbard model charge stripe and antiferromagnetic spin order are intimately coupled, as both are signatures of the same ordering instability of interacting itinerant charges. This model, however, discards charge immobilization effects, such as their trapping by local polarons. Doped holes in charge stripe picture are intrinsically highly mobile and decrease their energy by one-dimensional (1D) delocalization. While this assumption seems justified for moderately to highly doped cuprates, which show metallic conductivity and where an activated charge transport occurs only at low temperatures and is associated with the onset of CO in the form of "parallel stripes" aligned with Cu-O bonds [13], it is in question for lightly doped insulating cuprates and for the insulating nickelates [14,15], where CO corresponding to the so-called "diagonal" stripes with charge lines at 45• to Cu-O bonds is observed.In fact, cuprates are rather exceptional among MottHubbard insulators (MHI), as most MHI cannot be made metallic by doping: strong polaronic self-localization of doped holes hinders metallic transport [15]. Theoretically, however, stripe-like superstructures whose period depends on th...

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Design and construction of long-term gas hydrate production facilities requires assessment of the in situ formation response to production at a field scale. Fundamental properties, such as tem-perature and pressure, are critical for the determination of phase conditions. Other properties, such as formation resistivity, formation acoustic properties, and fluid mobility, support the inference of forma-tion permeability, porosity, and gas hydrate saturation. An ability to continuously monitor the changes in these properties during the course of a production test will facilitate tracking of the dissociation front and yield valuable information for engineering design and verification of numerical reservoir simulators. Such a monitoring system was designed, developed, and introduced as a part of the Mallik Gas Hydrate Production Research Well Program, carried out by the Japan Oil, Gas and Metals National Corporation, Natural Resources Canada, and Aurora College in the winters of 2007 and 2008 in the Mackenzie Delta, Northwest Territories. Although the deployment of some sensors and the acquisition of some data were limited by various operational challenges encountered during the field program, considerable experience was gained during all phases of the research program. In particular, the acquisition and interpretation of down-hole temperature profiles and changes in formation electrical potentials during testing provided use-ful insight into the stimulation-response behaviour of the reservoir, assisted in the understanding of a range of operational conditions, and supported critical decision-making processes at the well site.

Permanently installed monitoring-sensor cables behind the production-well casings were used to acquire distributed-temperature data, and electrical potentials were passively monitored at the down-hole electrodes in the winters of 2007 and 2008 for the JOGMEC/NRCan/Aurora Mallik Gas Hydrate Production Research Well Program. The data could be almost continuously acquired during the production-test periods without interfering with production operations once the down-hole-sensor cables were connected to the surface system. Some useful information related to production activities was obtained from the distributed-temperature data. The temperature-depth profiles obtained during the depressurizations in the 2008 test indicated a promising potential for tracking of the fluid levels in the annulus, which qualitatively corresponds to the fluid-volume change estimated from the differential pres-sures. Temperature profiles also contributed a complementary estimation of production parameters, such as the water-production rate under assumed conditions. The temperature disturbance observed during cement curing suggests a thermal impact on the gas hydrate by the heat of cement hydration. Passive electrical-potential measurement is considered a promising candidate for further development. The measurement was attempted to acquire streaming-potential signals from formation-fluid movement in porous media under the pressure gradient during various operations. Qualitative observation shows a rela-tionship between signal-polarity change and the direction of possible fluid flows in the formation, which suggests local-scale fluid flow near the electrodes.

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