An Investigation on the Process of Re-Imbibition of Oil and its Impact on Oil Recovery in the Yates Field

In mixed- to oil-wet reservoirs characterized by intense natural fracturing where the dominant displacement mechanism is gravity drainage, surfactant injection can lead to a shift in wettability and incremental oil production. In some cases, oil can also re-imbibe back into the rock matrix after the oil saturation has been reduced upon initial exposure to surfactant, suggesting limited permanence in the wettability shift. The re-imbibition phenomenon is investigated in this paper utilizing Amott cells. Three cationic surfactants (C12-, C12-16-, C16-based) solutions with interfacial tensions (IFT) between 0.18 to 0.95 mN/m were pre-selected to be evaluated. Current applications of the C12- based surfactant in the Yates field is considered successful based on incremental oil recovery seen during the treatment. Silurian dolomite rock samples were flooded with Yates crude oil before being aged at 140 °F for 6 weeks. For the imbibition tests, synthetic brine was set as the external phase within the Amott cell and the recovery of oil was recorded periodically. After the imbibition tests ended, the rock samples were placed in an inverse Amott cell with the Yates oil as the external phase. Baseline tests were first conducted to show that without a surfactant in the oil or brine, no imbibition occurred. With a surfactant concentration of 3,000 ppm, oil recovery at the end of the imbibition tests varied from 34% to 64% of the original oil volume in the core sample. During the re-imbibition test, a large amount of oil was able to re-imbibe into the rock, displacing the brine. Most of the displacement occurred within the first two weeks. The net oil recovery, taken as the final volume of oil recovered in the imbibition test minus the final volume of oil re-imbibed into the rock, ranged from 0% to 18%. Given the possibility of surfactant dilution in field applications, another set of tests were conducted with 1,500 ppm. A reduction in oil recovery during imbibition was observed for both the C12- based surfactant and the C12-16- mixture. Partition coefficients were determined for each of the tested surfactants and the ion pair mechanism was used to explain the net oil recovery results. Lastly, the impact of rock permeability on re-imbibition was investigated. Results show increasing permeability may lead to a linear response in oil re-imbibition,therefore minimizing the permeability range when selecting rock samples may be necessary when conducting the re-imbibition test. The importance of oil re-imbibition is demonstrated in the experimental study and we make an argument for conducting both the imbibition and re-imbibition tests to better evaluate surfactant efficacy. The improved understanding of wettability alteration should lead to advancements in chemical enhanced oil recovery designs for field treatments.

Experimental testing and numerical simulations of blast-induced fracture of dolomite rock

In this paper, the Johnson-Holmquist II (JH-2) model with parameters for a dolomite rock was used for simulating rock fragmentation. The numerical simulations were followed by experimental tests. Blast holes were drilled in two different samples of the dolomite, and an emulsion high explosive was inserted. The first sample was used to measure acceleration histories, and the cracking pattern was analyzed to perform a detailed study of the blast-induced fracture to validate the proposed method of modelling and to analyze the capability of the JH-2 model for the dolomite. The second sample was used for further validation by scanning the fragments obtained after blasting. The geometries of the fragments were compared with numerical simulations to further validate the proposed method of modelling and the implemented material model. The outcomes are promising, and further study is planned for simulating and optimizing parallel cut-hole blasting.

The Laboratory of the Picturesque

This chapter reconstructs the context of the geographical discovery of the dolomite rock and the position of the so-called Venetian Alps in the geological debates of the first part of the nineteenth century. This discovery will provide British travellers with a new picturesque toolkit to appraise the geomorphology of the Dolomites in architectural terms and promote them as a new tourist destination. The ingredients of that promotion were neither entirely British nor entirely contained within the experience of the Venetian Grand Tour. Before being ‘invented’ the Dolomites needed to be ‘discovered’ – their unique landscape features needed to be noticed before they could be seen. They needed to be placed on a map.

Mineralogical investigations on pozzolanic dolomitic lime mortars to assess the phase development at different curing conditions

<p>For a long time, historical mortars were primarily associated with mortars based on calcium carbonate as the main binder phase. Recent publications show that considerable amounts of magnesium are often present in the binder of historical mortars, which is referred to the use of dolomite rock as raw material (Diekamp, ​​2009; Diekamp, ​​2014). A special feature are Roman and medieval dolomitic lime mortars with the addition of brick fragments as a pozzolanic component (Schidlowski, 2019).In order to characterize the phase formation in modern pozzolanic dolomitic lime mortars, mortar prisms based on dolomitic lime were produced with three different pozzolans (antique and modern brick dust and metakaolin). To draw comparisons with other binders, identical prisms based on calcite and magnesite were produced. These specimens were stored under different environmental conditions (60 % and 95 % relative humidity) and examined by X-ray diffraction and simultaneous thermal analysis after periods of 28, 90 and 180 days.</p><p>The results obtained so far show that the binder phases that have evolved in the mortars based on dolomitic lime are calcite, aragonite, portlandite, brucite and AFm phases. Aragonite is only found in traces in the samples with metakaolin. In contrast to the samples stored at 65 % relative humidity, the samples stored at 95 % relative humidity have lower calcite and higher contents of portlandite and AFm phases.</p><p>No significant differences in the amount of calcite and water-containing mineral phases (portlandite, brucite, hydrotalcite) can be found after 28, 90 and 180 days. It can be concluded that a large part of the reactions has already taken place after 28 days.</p><p>The present study is believed to be beneficial for a thorough understanding of the phase formations in dolomitic lime based mortars at different curing conditions.</p>

Assessing the reactivity of magnesium oxide calcinated at different temperatures for understanding its role in degradation processes

<p>In Tyrol, Austria, dolomite rock was commonly used as raw material for historic mortars and plasters. During calcination of dolomite rock, almost equal amounts of calcium oxide and magnesium oxide are produced. While the reactivity of calcium oxide is well known, the reactivity of magnesium oxide is still not completely understood. Within this study, the reactivity of magnesium oxide obtained from calcination at different temperatures (600 - 1000 °C) will be examined. For this purpose, natural magnesite (Hochfilzen, Tyrol) will be used instead of natural dolomite rock in order to minimise the influence of calcium oxide on the wet slaking curves. Both, calcination and slaking of magnesite will be studied with the help of X-ray diffraction analysis and thermogravimetric analysis. The gained knowledge is believed to be beneficial for improving the understanding of degradation processes. The study was performed within the Interreg V-A Italy-Austria project named DOLOMIA (ITAT 2036) with the funding by INTERact and the European Regional Development Fund (ERDF) being grateful acknowledged.</p>

Analisis Kestabilan Lereng di Bukit Tui Section S0° 28’ 50.23” E100° 24’ 16.89”- S0° 28’ 49.19” E100° 24’ 17.07” Kecamatan Padang Panjang Barat Kota Padang Panjang

Tui Hill is a limestone hill lined south of Padang Panjang, located between Rao-Rao Village to Tanah Hitam. The results of research at Tui Hill at the location S0° 28’ 50.23” E100° 24’ 16.89”- S0° 28’ 49.19” E100° 24’ 17.07” located in Tanah Hitam Village has a covered dolomite rock slope. Based on the Indonesian earthquake zoning map, the city of Padang Panjang is classified as a high earthquake vibration zone, ranging from 0.8-0.9 g. The potential for landslides on the slopes of the study can lead to the closure of the access road to dolomite mining so that it can hamper road user traffic and disrupt mining production as well as potential material losses and fatalities This study aims to determine the Safety Factors on earthquake slope research and recommendations to increase the value of Safety Factors (FK). Based on the results of the analysis by simulating earthquake vibration values the maximum earthquake vibration values that can be held by slopes in a safe condition is 0.2 g or equivalent to 6.4-6.6 on the Richter Scale, namely with FK of 1,281. Then, the author issued for the slope by changing the slope of the slope from 53˚ to 25˚ increases can obtain a slope FK value of 1.438, according to Joseph E. Bowles (1984) the slope is in accordance with the safe conditions.