Journal of China University of Petroleum (Edition of Natural Science)

Multivariable coordinated control of managed pressure drilling process based on comprehensive performance index

With the recent advance in high speed data communication offered by wired drill pipe (WDP) telemetry, it is now possible to design automated control systems that directly utilize downhole data (e.g. pressure) to optimize drilling procedures. This research couples drilling hydraulics, rate of penetration (ROP), and rotational speed (RPM) control into a single controller for managed pressure drilling systems. This novel multivariate controller improves drilling performance during normal drilling operations and enhances safety during abnormal drilling conditions such as unwanted gas influx sit

Microstructure and property of TIG welding joint of nickel foam sand screen tube

The usage of AISI/SAE 304L austenitic and 420 martensitic stainless steels is receiving greater interest especially in the defence and navy industries. 304L stainless steels exhibit excellent resistance to oxidizing media, while martensitic 420 alloy provides high strength values besides satisfactory corrosion properties at ambient atmospheres. In this work; 420 quality martensitic stainless steel is TIG (Tungsten Inert Gas) welded with 304L quality low carbon austenitic stainless steel plates. As filler metal dominantly determines the weld metals chemical compositions and final microstruct

A new stability analysis method for steel dome of large LNG storage tank

The design of roof frame is one of the most important parts of LNG tank design. In China, however, the calculation of roof frame system of extra-large LNG tanks is currently faced with a series of problems. For example, there is no united yardstick on buckling characteristic value, the calculation is based on many assumptions, and the calculation is inconsistent with domestic specifications and stipulations. In view of these problems, the material non-linearity and structural non-linearity were introduced and the initial defect was taken into consideration. Then, the large non-linear finite

Influence of EVA/asphaltene composite pour point depressant on rheological properties of Qinghai waxy crude oil

Lauramine is widely considered to be an asphaltene flocculant, but its effect on the modification of crude oil by PPDs has been little studied. In this paper, the effect of LA dosage on the rheology improvement of EVA PPDs (100 ppm) on Qinghai waxy crude oil was investigated through rheological measurement, wax precipitating analysis, granularity test and resins/asphaltenes FTIR analysis. Compared with pure EVA, the compounding of LA and EVA obviously enhances the agglomeration degree and reduces the number of fine wax crystals, thus further enhancing the rheology of the oil samples, and th

Composition characteristics of soluble organic matter in marine-continental transitional mudstone in North China

Organic-rich marine-continental transitional shale is widely developed in the Permian Shanxi Formation in the Southern North China Basin. In this study, shale samples from the southern and northern wells of the basin were characterized by X-ray diffraction, high-pressure mercury intrusion porosimetry, low-pressure gas adsorption (N2 and CO2) and argon ion polishing-field emissions scanning electron microscopy. The pore types and structures of shale micropores, mesopores and macropores are qualitatively described; their pore size distribution and volume are quantitatively characterized; and

Journal of China University of Petroleum (Edition of Natural Science)