<p> This experiment was designed to study iron control systems in fracking and well stimulation jobs at higher pH. Experimental study of iron control at high pH of this kind has not previously been reported in the literature. In addition, almost all of the widely used iron control chemicals today work at lower pH (&le;4). </p><p> In this experiment, newly enhanced chemicals, such as EnerFlow 780, SC803, EDTA, Poly Itaconic acid, and TN801 were used and the following new result were found. In the absence of iron control chemicals, iron precipitation occurred at pH of 1.85 and completely precipitated at 3.5. <b>SC803</b> has shown a very unique characteristic. The chelating characteristic of this product increases with pH. At lower pH (&le;4), this product has shown weaker performance in curbing iron precipitation. Only 37% (average) initial iron was prevented from precipitating at this pH. However, when the pH was increased to above 4, its sequestering characteristic became more and more until it reached pH 13. Minimum precipitation was observed at pH of 11 &amp; 12, which are 4.3% and 4.7%, respectively. Furthermore, SC803 was observed to cause unforeseen yellowish iron precipitation at lower pH. </p><p> <b>TN801,</b> a blend of SC803, EDTA and Poly Itaconic acid, showed the best result of the all the individual chemicals tested. It effectively curbed an average of 96% iron precipitation in all pH less than 13. EDTA and Poly Itaconic acid were added to enhance the performance of SC803 at lower pH. The result showed 86.8% maximum enhancement at lower pH and 0.3% at higher pH. TN801 was also able to dissolve 50% of crystalline iron sulfide, despite the fact that it is insoluble in nature. Furthermore, TN801 was tested on field and the anticipated result was achieved.</p>

Measuring the difference between the measured hydrocarbon thickness in an observation well and the actual hydrocarbon thickness in a formation has been a major hinderance in estimating the volume of free product in aquifers. The thickness of hydrocarbons in some observation wells is as much as four times greater than in the formation. A three-dimensional sandbox model was used to determine linear relationships between the height of hydrocarbon in an observation well to the thickness of hydrocarbon above the water table. A fine-grained sand was used to calibrate the system, then two soils were characterized and modeled. The results of the sand and natural soil runs were compared with three models found in the literature. The linear relationships developed from the sandbox experiments compared favorably with the models in the literature. Further investigation with a more accurate petroleum thickness detection method will result in site-specific linear relationships.

<p>The essence of many issues in different fields is the transport and piling of particles in fluid within a limited space. A semi-analytical model is developed in this study to describe the motions of a particle in fluid and simulate the piling process of particles in a fracture. As a result, the configuration of a particle pile and the time at which the pile totally seal the fracture face are predicted. This model possesses a wide range of applications. Two types of applications of this model are introduced, including the prediction of proppant screen-out in hydraulic fracturing vertical and horizontal wells and the simulation of curing the lost circulation. Results of case studies are consistent with the field data with minor errors. Sensitivity analyses with the proposed model were conducted for each type of application. Major factors affecting the model calculation results are identified for the purpose of optimizing the performance of hydraulic fracturing and curing the lost circulation. Sensitivity analyses conducted for the proppant screen-out prediction during fracturing vertical and horizontal wells indicate following conclusions: 1) The use of high fluid viscosity can avoid the premature settlement of proppant and significantly delay the screen-out time. 2) The sse of proppant with low density in the practical range could delay the screen-out time, but the effect is not as significant as other factors analyzed in this study. 3) A high injection rate allows the proppant pile to build farther from the wellbore, while it will lead to a quick screen-out. 4) Larger proppant size can easily cause screen-out sooner. 5) Wide distributionof proppant size can delay screen-out. 6) The use of low ratio of proppant volume to fluid volume can minimize the probability of the occurrence of screen-out. Sensitivity analyses for the cure of lost circulation demonstrate following conclusions: 1) Lost circulation can be cured faster when low fluid viscosity is used. 2) High density LCM can facilitate the cure of lost circulation. 3) Low mud density can mitigate lost circulation, but its effect is not as significant as other factors. 4) The concentration of LCM should be determined based on the severity of lost circulation. This semi-analytical model provides engineers a general tool to solve different issues involved in different fields. It can also be utilized to identify main factors responsible for different issues to minimize their detrimental effects.

<p> Ceramic proppants are commonly used in hydraulic fractures. However, people typically focus on controlling properties of proppants such as the material, specific gravity, and particle size, and less attention is paid to the effect of proppant wettability. The purpose of this study is to investigate the effect of proppant wettability on two-phase flow efficiency in fractured water-wet sandstones. The results show that oil-wet proppants are more effective in improving oil flow efficiency than water-wet proppants in both low-water saturation cores and high-water saturation cores. Therefore, small sized oil-wet proppants have better performance than large sized oil-wet proppants. </p><p>

<p> Hydraulic Fracturing is a cost-effective technique that has been widely integrated and applied to commercial production of oil and gas from unconventional reservoirs. Advancement of this technique brings more complexity into it, making optimization process more complicated in terms of economic analysis and decision making. Selection of proppant for treatment is a crucial and essential decision that has a significant impact on fracturing stimulation and well economics. This analysis indicates advantages and disadvantages of different types of proppant and provides a comparison of proppant performances considering proppant type, mesh size and concentration in order to identify the best scenario of proppant application in terms of economical profitability. </p><p>

<p> Abstract In this work, we studied the Eagle Ford Shale and experimented in detail to create a baseline to address the relative permeability of specific ions in shale. The study identifies that: (1) Ions are dispersed in a specific sequence (Na⁺, Ca²⁺, Mg²⁺). (2) As ions are dispersed, this allows the gas bubbles out of the shale/soil and forces the flakes and fragments to float to the top of the water on the vessel. The floating particles, depending on the type of cations released from the shale mass move towards a specific ion electrode. (3) Detachment or bursting of gas bubbles may initiate a shift or break in the shale/soil formation. (4) Calcium electrical potential, Eh, goes from negative to positive. This indicates an unstable potential with respect to time around the length of the well bore. (5) The release of ions depends on the diffusion properties of water penetrating the shale/soil mass. The motion of the shale/soil floating material is a vortex-like motion. </p><p> We conclude that by using SAR, it will help predict where the wellbore is stable or unstable based on the curve where certain drops or peaks or located. By creating a baseline measure using deionized water it is possible to predict the relative permeability of wellbore drilling of the Eagle Ford Shale using SAR. </p><p> Taking note of the ionic relative permeability as observed in our experiments, we decided to use the SAR method for estimating the relative permeability of shale/soil to various ions. All of this is based on where the most ionic flow occurs under given wellbore conditions. This understanding is further applicable to the design of certain type of frac fluids or design of a compatible drilling fluid for drilling a specific shale/soil.</p><p>

<p> The lack of cutting transportation during drilling operations can lead to large amounts of non productive time and costly solutions to address the issue. The objective of this study was to investigate the cutting velocity through an experimental approach. Dimensionless groups were formed based on the independent variables that affected cutting velocity. The experimental approach was analyzed through film software, which allowed for the cutting velocities to be calculated. Regression models of cutting velocity with respect to each dimensionless group were formed and validated through a statistical analysis. Only the second dimensionless group (?2) representing the volume of cuttings injected into the drillpipe with respect to the cubed value of the outer diameter of the drillpipe was proven to be insignificant. </p><p> Once the remaining regression models were validated, multiple linear regression analyses were conducted to relate each dimensionless parameter to the cutting velocity. This introduced a new empirical model to represent the cutting velocity based on the five significant dimensionless groups outlined in this study. The multiple linear regression model yielded an R-squared value of .81, which suggests a strong correlation for the data. This model was also validated through statistics. Each parameter except for the intercept of the model was confirmed to be significant. Other parameters that were excluded from the model due to the lack of equipment precision could be examined. A sensitivity analysis was conducted to highlight how each dimensionless group directly affected the cutting velocity. New correlations and trends may be estimated with more data from additional experiments outside the range of this study. Overall, this will allow the foundation of the model to be further improved.</p><p>

<p> Superhydrophobic coating reduces the fluid/solid interaction leading to ultra-hydrophobicity or the Lotus effect. The objective of this study is to determine how this phenomenon can be applied in petroleum production systems to enhance fluid flow in propped fractures using superhydrophobic coating on the surface of proppants. Permeability and wettability of coated sandstone samples are compared with the non-coated ones to create a base case for the study. Later sand packs are tested to determine the magnitude of enhancement in fracture conductivity after the modification is applied on sand proppants. The samples are measured for their absolute permeability and relative permeabilities to test the changes in flow for both the single-phase and two-phase fluid flow. The test results show a considerable increase of up to 98% for the single-phase flow and a 23% for the two-phase flow for the sand pack samples. The wettability test confirms that the coating modifies the samples from its initial water-wet state to a partial-wet state. Since the production rate of tight and shale reservoirs is low especially in liquid-rich reservoirs, a significant amount of water is injected for reservoir stimulation; enhancement in fracture conductivity as a result of proppant surface modification can have a meaningful impact on the recovery of these reservoirs. This study uses experimental techniques to show the effectiveness of superhydrophobic coating on the reduction of friction which can lead to enhancement in fracture conductivity. </p><p>

<p> It has been reported that the Macondo tragedy was caused by a faulty cementing operation. This, in turn, has forced operators to pay special attention to this aspect of well completion. One of the contributing factors to the faulty cementing operation of Macondo is said to be an insufficient number of casing centralizers. This is important because the success of any casing cementing operation is largely dependent on the centralization of the casing in the wellbore.</p><p> Centralizers are placed on the casing strings at predetermined distances in an effort to retain the casing in the center of the wellbore, thereby maximizing the coverage of cement around the casing. Placement, as well as the number, of centralizers is dependent on the standoff of the casing in the wellbore. Standoff is defined as the minimum distance between the outer diameter of the casing and the wellbore.</p><p> For casings under tension, API has recommended formulas to calculate casing standoff in 3D wellbores, which takes into account the inclination and azimuth angles. In addition, literature is available that considers casing under compression due to the fluid forces acting on the casing string and shows a considerable difference in standoff when considering compression as compared to tension alone. Currently all available literature considers the wellbore as rigid only. This paper considers the formation type, ranging from unconsolidated sand to shale, and calculates its effect on standoff. The results show that the formation type may significantly affect the outcome of standoff, and therefore should be considered when calculating standoff. </p>

This study created a new tectonic model for the Arctic Alaska terrane (AAT) by connecting attributes interpreted from surface and subsurface maps. Lineaments that cross the Brooks Range and North Slope proclaim the presence of basement fault blocks trending to the northeast that locally are aligned with streams, coast and lake shorelines, submarine canyons, and periglacial features. These landforms and anomalies reflect upward propagation of long-lived transcurrent and rift fault fabrics. Facies mapping and analysis of heat-flow effects on permafrost, and data from aeromagnetic, gravity and reflection seismic surveys, support the correlation of basement faulting with geomorphic patterns. The conjugate pattern of fault blocks, seen across Paleozoic- and Mesozoic-age passive margin sequences, resembles a piano keyboard and was inherited from older rift margin and transcurrent-transfer faults. Seismic data and North Slope oil-reservoir characteristics reveal complex fault-block boundaries, and common fault reactivation and structural inversion. The rigid North American craton in the Yukon Territory directs deformation westward leading to continued crustal indention, migration of basement blocks, and thrusting of cover rocks north of the Arctic oroclinal bend. Differential south-vergent underthrusting and uplift of the basement blocks of the North Slope plate has episodically segmented and partitioned strain across the overlying weaker north-vergent cover rocks of the North Alaskan plate. These tectonic controls have influenced the structural and geomorphic evolution of the North Slope-Brooks Range foothills region, including the formation of oil and gas reservoirs and mineral deposits.