IMPROVING RESERVOIR TESTING AND SAMPLING IN H2S CONTAMINATED FLUIDS BY ADAPTING STATE-OF-THE-ART SEMICONDUCTOR THIN FILM TECHNOLOGY FOR DOWNHOLE TESTER TOOLS

Accurate reservoir fluid identification and sampling of hydrogen sulfide (H2S) contaminated fluids is difficult to achieve due its consumption by the interior of downhole tool surfaces prior to sampling or measurement. For low PPM level concentrations, this fact does not change, despite recent tool advances utilizing NACE compliant materials. Consequently, H2S concentrations are typically under-reported which adversely affects production and presents significant health safety and environment concerns. Historically, only sampling bottles have been coated to preserve H2S concentrations during transit to laboratories with a material that is resistant to H2S reactivity to enable more representative measurements. However, only very recent efforts have transitioned the focus toward successfully coating the interior of the tools. This paper details a state-of-the-art technology, initially developed and heavily leveraged from the semiconductor industry. The technology is adapted to coat the interior surfaces of downhole tools with a chemically resistant dielectric thin film. New developments now provide the benefit of the process being safe, able to be performed at atmospheric pressure and temperature conditions, and portable; thus, allowing the coating process to be deployed to field locations. The method involves atomic layer deposition (ALD) technology to be plumbed in directly to a downhole tool and conformally deposit a thin layer (e.g. < 1 micron) of highly durable H2S-resistant sapphire to the entire interior tool surface. An automated procedure has been developed allowing the versatility to accommodate a number of unique geometries inherent of different formation tester configurations. New advances in Quartz Crystal Microbalance sensors are also realized in-situ to optimize (in real-time) the efficiency of the process and ensure uniform and conformal coverage is obtained in the fastest and safest manner. Laboratory testing on a prototype system demonstrated uniform and conformal coverage of a ~ 500 nm thick sapphire film resistant to flaking and scratching. Accelerated lifetime stress testing demonstrated high durability relative to expected tool life. Testing of coated and uncoated tools show the coating is successful at the 50ppm level H2S for up to 4 days. These results are contrasted with similar tool body samples not coated with the H2S-resistant ALD sapphire and subject to the same H2S conditions. To show the coating’s durability, subsequent experiments flowed mud-based drilling fluid through both the tool body and sample chambers, followed by thorough cleaning and successful repeating the same 50ppm H2S test. Exposure of the sapphire coated tool body and sample chambers to various concentrations of H2S demonstrated zero loss. Ultimately this technique represents a new opportunity to gather representative formation samples containing low concentrations of H2S.

Effects of O2 Plasma Treatments on the Photolithographic Patterning of PEDOT:PSS

Poly (3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) is known for its potential to replace indium–tin oxide in various devices. Herein, when fabricating finger-type PEDOT:PSS electrodes using conventional photolithography, the cross-sectional profiles of the patterns are U-shaped instead of rectangular. The films initially suffer from non-uniformity and fragility as well as defects owing to undesirable patterns. Adding a small amount of hydrolyzed silane crosslinker to PEDOT:PSS suspensions increases the mechanical durability of PEDOT:PSS patterns while lifting off the photoresist. To further improve their microfabrication, we observe the effects of two additional oxygen (O2) plasma treatments on conventional photolithography processes for patterning PEDOT:PSS, expecting to observe how O2 plasma increases the uniformity of the patterns and changes the thickness and U-shaped cross-sectional profiles of the patterns. Appropriately exposing the patterned photoresist to O2 plasma before spin-coating PEDOT:PSS improves the wettability of its surface, including its sidewalls, and a similar treatment before lifting off the photoresist helps partially remove the spin-coated PEDOT:PSS that impedes the lift-off process. These two additional processes enable fabricating more uniform, defect-free PEDOT:PSS patterns. Both increasing the wettability of the photoresist patters before spin-coating PEDOT:PSS and reducing its conformal coverage are key to improving the photolithographic microfabrication of PEDOT:PSS.

Bacterial Cellulose Aerogels Skeleton Strengthened by Regenerated Cellulose

Soft skeleton of bacterial cellulose aerogels (BCAs) was strengthened effectively by conformal coverage of regenerated cellulose to make sure the BCAs sustain more compression. After freeze drying, compression modulus of the strengthened sample is significantly higher than that of the BCAs, which endows the former more extensive applications. The regenerated cellulose solution was prepared by gelation of cellulose from aqueous alkali hydroxide/urea solution. Then the bacterial cellulose wet gels bulks were immersed in the regenerated cellulose solution with different contents to discuss the enhanced effect of the BCAs skeleton. The morphology of the enhanced BCAs was observed by scanning electron micrograph (SEM).The porous structure of the enhanced BCAs was investigated by Brunauer-Emmett-Teller (BET) instrument. The stress−strain curves of the enhanced BCAs were measured. The XRD pattern of the strengthened sample was also carried out. The results indicated that regenerated cellulose forms thin layers which conformally covered bacterial cellulose skeleton fibers and that had little effect on microstructure and crystal form of the bulk cellulose aerogels.

Synthesis of Pt nanowires with the participation of physical vapour deposition

The following paper presents the possibility of formation of Pt nanowires, achieved by a three-step method consisting of conformal deposition of a carbon nanotube and conformal coverage with platinum by physical vapour deposition, followed by removal of the carbonaceous template. The characterization of this new nanostructure was carried out through scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray diffraction (XRD).

Low Temperature Metalorganic Chemical Vapor Deposition of Semiconductor Thin Films for Surface Passivation of Photovoltaic Devices

ABSTRACT Three II-VI wide bandgap compound semiconductors have been investigated for surface passivation of various photovoltaic devices. First part of this work focuses on the surface passivation of HgCdTe IR detectors using CdTe. A new metalorganic chemical vapor deposition (MOCVD) process has been developed that involves depositing CdTe films at much lower temperature (&lt; 175°C) than the conventional processes used till now. Deposition rate as high as 420nm/h was obtained using this novel experimental setup. Favorable conformal coverage on high aspect ratio HgCdTe devices along with a significant minority carrier lifetime improvement was obtained. Another II-VI semiconductor, namely, CdS was investigated as a surface passivant for HgCdTe IR detectors. It was deposited by MOCVD as well as atomic layer deposition (ALD) and was studied for optimal conformal coverage on high aspect ratio structures. Surface passivation of p-type Si wafer has also been demonstrated using p-ZnTe grown by MOCVD, for possible application in solar cells. Preliminary work showed a remarkable improvement in the minority carrier lifetime of Si light absorbing layer after passivation with a thin layer of ZnTe.