well testing

Well-testing is the analysis of reservoir and well behavior based on time. Obtaining the true value of changes in reservoir parameters plays a major role in creating an accurate and current model of the reservoir. The most crucial factor in achieving this objective is pressure, which is determined by a downhole pressure gauge. Operational issues and additional expenses are brought on by the use of pressure gauges at the well's bottom for the employer company. Surface well testing, which installs flow and pressure measurement devices at the wellhead, is another approach to well testing. The benefits of this technology include a significant cost reduction, ease of installation and data collection, easier operations, reduced risk, the ability to collect data for extended periods of time, and the ability to determine the impact of borders in large reservoirs. The difficulty of calculations and the insertion of errors as a result of the impact of well-column circumstances on the recorded data are the method's most significant issues. In this study, using Pipesim software, data obtained at the surface of a well located in a conventional undersaturated oil reservoir is converted to bottom-hole data, then analyzed, and finally, the properties of the reservoir are obtained. In comparison to the conventional well test method, the results demonstrate that the surface well test method can accurately forecast permeability, skin, productivity index, average pressure, and reservoir radius with error rates of 6.2, 17.3, 4, 7, and 13.3%, respectively.

Investigation of behavior of non-persistent joint is important in rock structure stability. This leads to improvement in rock engineering project design. Rock bridges in non-persistent joint increase shear strength of failure surface. For investigation of shear behavior of rock bridge, 24 gypsum samples with dimension of 10 cm × 10 cm × 5 cm were prepared. The joint lengths in various samples are different but in the one sample the joint length are similar. Joint lengths change from 1 cm to 4 cm. in each joint length, joint angularity was 0, 15, 30, 45, 60, 75 degrees. These samples were tested under uniaxial compression test. The results show that failure pattern was affected by joint length, joint angularity and rock bridge length while failure load was controlled by failure pattern. Concurrent with experimental test, numerical simulation was performed using PFC2D software. The joint lengths in numerical model change from 1cm to 4 cm with increment of 1cm. In each joint length, the joint angularity is 0° and 45°. Failure pattern in numerical model was similar to experimental sample while failure load in numerical model was more than experimental outputs.

Presently، a large number of civil and mining openings are excavated by mechanized machines. Similarly، geotechnical and mining boreholes as well as oil and gas wells are drilled as a result of penetrating bits in rock. The efficiency of such devices requires a full understanding of geological and geotechnical conditions of the working environment. One of the most important parameters in estimating costs and efficiency of mechanized excavation is wear properties of rock. In this paper، different rock abrasivity testing methods are briefly reviewed Furthermore، by introduction of a simple rating system for various methods، their efficiency، in relation to evaluation of wear in disk cutters of TBMs، is estimated. Based on the results، the Cerchar test can be used as a low cost and relatively efficient method to evaluate abrasivity of rocks. However، investigations showed that Cerchar method، despite its relative high efficiency، has significant shortcomings in evaluating the abrasive capacity of rock.