Well integrity is becoming a subject of increasing interest with current developments in technical, political and social aspects echoing over the oil and gas industry. Both onshore and offshore activities are strongly constrained by the operator's ability to provide solid facts regarding their well integrity over the life of the well. As a result of new technologies, the life of the well has increased, generating new questions about novel integrity tiers. This paper presents the new cement repository that is currently under development at OU. The concept is to create a physical storage unit as well as a cement database to hold cement samples for a minimum of 5 years after well spud. All information will be stocked on a custom-made database, whereas the cement samples will be kept in a special "cement bank" - holding the cement samples under constant in-situ pressure. The cement samples can be taken during normal cementation jobs at the well site, transported using a "for purpose" developed mobile autoclave system and stored in the special units that will be built at OU. Additional samples (reference units) will be manufactured at the OU Well Integrity Laboratory. The paper will demonstrate that in case of any wellbore integrity issues, wellbore owners will have immediate access to accurate cement properties that can be used to perform numerical studies on the wellbore cement situation.

Geothermal energy has been used by mankind since ancient times. Given the limited geographical distribution of the most favorable resources, exploration efforts have more recently focused on unconventional geothermal systems targeting greater depths to reach sufficient temperatures. In these systems, geothermal well performance relies on efficient heat transfer between the working fluid, which is pumped from surface, and the underground rock. Most of the wells designed for such environments require that the casing strings used throughout the well construction process be cemented in place. The overall heat transfer around the wellbore may be optimized through accurate selection of cement recipes. This paper presents the application of a three-phase analytical model to estimate the cement thermal properties. The results show that cement recipes can be designed to enhance or minimize heat transfer around wellbore, extending the application of geothermal exploitation.

Centrifugal pumps are widely used in the industry, especially in the oil and gas sector for fluids transport. Classically, these are designed to transfer single phase fluids (e.g., water) at high flow rates and relatively low pressures when compared with other pump types. As part of their constructive feature, centrifugal pumps rely on seals to prevent air entrapment into the rotor during its normal operation. Although this is a constructive feature, water should pass through the pump inlet even when the inlet manifold is damaged. Modern pumps are integrated in pumping units which consist of a drive (normally electric motor), a transmission (when needed), an electronic package (for monitoring and control), and the pump itself. The unit also has intake and outlet manifolds equipped with valves. Modern systems also include electronic components to measure and monitor pump working parameters such as pressure, temperature, etc. Equipment monitoring devices (vibration sensors, microphones) are installed on modern pumping units to help users evaluate the state of the machinery and detect deviations from the normal working condition. This paper addresses the influence of air-water two-phase mixture on the characteristic curve of a centrifugal pump; pump vibration in operation at various flow rates under these conditions; the possibilities of using the results of experimental investigations in the numerical simulations for design and training purposes, and the possibility of using vibration and sound analysis to detect changes in the equipment working condition. Conclusions show that vibration analysis provides accurate information about the pump's functional state and the pumping process. Moreover, the acoustic emission also enables the evaluation of the pump status, but needs further improvements to better capture and isolate the usable sounds from the environment.Processes 2018, 6, 18 2 of 15 refers to the difficulty of finding a general analytical model that explains the changes of the pump characteristic curve [3,6].The development in materials and pump construction have led to an increased life time and better reliability of the products. The pump application may limit the access of personnel for a thorough visual pump inspection, so that under these conditions, the use of non-intrusive sensors can replace humans for detecting pump failure. Sometimes, air entrapment does not necessarily lead to a major failure, hence the pump may work under two-phase flow until a replacement/solution is found. However, as the pump characteristic is changing, the control system needs to know how to adjust the pumping parameters accordingly, so that the pump runs under safe conditions. This paper shows the concept of how the pump characteristic curves transform from the normal state to the conditions of circulating a two-phase mixture. Several papers have shown and demonstrated the ability of vibrations measurement as an effective solution to identify improper machine state (such as valve opening or pump vibrations) [8][9][10][11][12...

Well cements are an important aspect of wellbore integrity and recent investigations focus on describing the cement lifetime using, when possible, nondestructive tests like ultrasonic measurements. However, the original API and ASTM testing standards were based on destructive mechanical testing of cements, leading to the decision to investigate the backward and forward compatibility between ultrasonic measurements and mechanical testing, which makes the subject of this work. Ultrasonic cement measurement became a very popular method to assess the mechanical properties of the cement in a nondestructive manner. Since various measurement systems exist on the market, the development of an accurate reference data base that can be used to calibrate such measurements becomes very important. Two major systems have therefore been compared: the ultrasonic compressive strength, using the ultrasonic pulse velocity (UPV) principle, and the unconfined compressive strength (UCS), using the standard testing frame according to API and ASTM standards. The tests have been performed at different curing times, using both devices, on API Class G cements with bentonite and other additives. This paper presents the results of over 200 experiments that have displayed a different UPV response as a function of the additive content. Cement specific UPV versus UCS correlations were established. Thereby, a new level of accuracy was reached. Moreover, it was observed that after a given curing time, depending on the additive and its concentration, the UPV response is not as sensitive as the results yielded by the UCS method. The outcomes are an important step forward to improve and understand the wellbore integrity.

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