bluuebunny/crossref_metadata_2025_split huggingface dataset:
Oil-Displacement Characteristics and EOR Mechanism of Amphiphilic Polymers With Two Molecular Weights
Authors: Zhang Xiangfeng , Yang Hongbin , Wang Pengxiang , Guo Shujun , Cao Changxiao , Chen Chao , Kang Wanli 
Published: October 2018

Abstract
Amphiphilic polymers applied in oil production are usually polymer mixtures with wide distribution in molecular weight. To determine the performance of oil displacement of polymer with specific molecular weight, it is essential to employ precipitation method to separate polymer mixtures into two molecular categories, including high molecular weight category (HM component) and low molecular weight category (LM component). The separated categories are characterized by FTIR. The rheology properties of the separated categories are evaluated by static and dynamic rheology methods. The aggregation behavior and thickening mechanism of both molecular categories is analyzed by SEM intuitively. Emulsification performances are investigated by analyzing the kinetic stability and rheological rules. Finally, displacement efficiency of the two categories is achieved by core flooding. Experimental results of CT scanning for the displaced cores and microscopic model reveal the distribution of residual oil and the mechanism of oil displacement, respectively.
The observed structural analysis indicates similar molecular structures for separated categories. However, the grafting density of the LM is higher than that of the HM. The viscosity of the LM drops more as compared to that of HM. In contrast, viscoelastic properties of LM are better than that of the HM in solutions. Emulsion particle size of HM increases at a certain degree while that of LM decreases. The stability of LM emulsion is stronger as compared to that of HM. LM is more conducive to the stability of the emulsion system owning to more hydrophobic group and better emulsion viscoelastic properties than the HM emulsion. Oil recovery efficiency of the LM reaches 54%, 5% higher than that of the HM, which indicates that the LM is more conducive to enhance oil recovery. Core flooding results suggest that the oil displacement mechanism of the HM is via mobility control, and eventually enhance the sweep efficiency; LM improves the ability of emulsifying crude oil, and thus enhance oil recovery; and synergistic effect after compounding of different molecular weight polymers showed the highest EOR effect.
Current study is of great significance for the synthesis of amphiphilic polymer and oil field applications. A polymer system with proper molecular weight distribution and grafting density can effectively improve oil recovery for a polymer flooding.
Reduced the Adsorption of Guar Based Hydraulic Fracturing Fluids in the Formation
Authors: Yin Zichen , Wang Yanling 
Published: October 2018

Abstract
Guar based hydraulic fracturing fluids is the most commonly utilized fracturing fluids in oil field. Whereas, it tends to lead to formation damage as a result of adsorption of guar. The adsorption behavior of guar was investigated. The approach for reducing the adsorption was explored in order to achieve the decline of formation damage and improve oil recovery. Firstly, determination method of the guar concentration was obtained via establishing the standard curve. Then, spectrophotometer was used to measure the absorbance of guar before and after adsorption on adsorbent. The obtained absorbance of guar was utilized to determine the adsorption capacity of guar on adsorbent and quantitatively demonstrate the adsorption properties of guar in the reservoir. Finally, the effect of pH, temperature, salts, alcohols and polymers was studied in order to select the condition in favor of reducing the adsorption. The linear relationship between absorbance and concentration can be detected. A simple way to determine the adsorption of guar was established: the adsorption capacity can be determined by absorbance. With increase in pH, the adsorption decreased. There was decrease in adsorption when temperature increased. Monovalent cation inorganic salt resulted in the decrease of adsorption while multivalent cationic inorganic salt and multivalent anionic inorganic salt led to the increase of adsorption. The addition of monobasic alcohol did not affect the adsorption behavior. On the contrary, the addition of ethanediol decreased the adsorption. When adding partially hydrolyzed polyacryamide (HPAM), the adsorption of guar can be decreased. Based on the above results, it can be inferred that the decline of adsorption can be achieved under the condition of high pH, high temperature, monovalent cation inorganic salt, ethanediol and HPAM. The determination approach for guar adsorption was established. The adsorption capacity was determined through the established method. The different influence factors were investigated, and the condition and method were obtained in order to decline the adsorption of guar in formation, thus reducing the formation damage.
Enhancing Plant Operability Through Control System Integration While Construction and Commissioning Phases
Authors: Farahat Abdallah , Eid Said , Abdelrazek Moustafa , Badawy Mohamed , Rostom Mohamed 
Published: October 2018

Abstract
Nowadays, Centralized control system becomes a key feature in designing and operating plants. It facilitates advanced control, enhance maintenance, ease troubleshooting and reduce the man power.
Agiba Petroleum Company rented a gas plant. It was constructed in western desert, Egypt to treat the production of 10 gas wells. The main facilities in this plant is separators, low temperature separator (LTS), membrane units, exchangers and compressors.
The paper presents the work done to integrate the control system of the gas plant with the units outside the plant boundaries which are launcher PLC, inlet manifold, methanol tank, well head control panel system and existing oil plant control system.
In construction phase, a field feasibility study was performed to identify the availability in Gas plant's control system, emergency shutdown, and fire and gas system. The study also includes the cables routing and the quantities of cable, glands and cable entries. It also shows the work breakdown structure (WBS), resource breakdown structure (RBS) and the schedule to perform these modifications. After performing this study, an engineering documents was issued including modified layout, cable routing, cause and effect documents and control system programing update.
This modification enhanced operations safety by give alarming and shutdown signals between the existing oil plant and gas plant, it also reduced the number of filed operators that shall monitor remote areas like the inlet manifold, launcher area and methanol tank. The paper gives an idea about workaround plans and logical engineering studies and steps that were used in critical situation to enhance the safety, promote plant operation and reduce labor.
Numerical Simulation of Gas Injection for Stable Gravity Combination Flooding After Polymer Flooding
Authors: Gao Ming , Wang Qiang , Ma Desheng , Liu Wanlu , Liu Zhaoxia , Wang Zhengbo 
Published: October 2018

Abstract
Remaining oil after polymer flooding is very scattered, and the remaining oil in top sections is extremely difficult to develop, yet there is no prevailing technology suitable for developing the reservoirs after polymer flooding. Gas injection for stable gravity combination flooding is studied by force analyses and numerical simulation.
The force condition of oil droplets in porous media was studied in this paper, and the action of buoyancy on oil droplets was considered during different stages of oilfield development. Based on the analyses of stress on oil, the idea of injecting gas at the top sections of the reservoir and conducting ASP flooding at the bottom sections has been proposed in this paper. Performances of different displacement modes have been predicted for the block in Daqing oil field after polymer flooding.
The research results showed that gas injection for stable gravity combination flooding had the best performance with an EOR increment of 13.53%. Comparing the remaining oil saturation of different displacement modes, the low permeability formations in the top section was effectively flooded and the remaining oil of whole formation was reduced significantly by gas injection for stable gravity combination flooding. Vertical remaining oil distribution at different time points was analyzed. Because of differential pressure in vertical direction, the remaining oil was driven to migrate downward after injecting gas in the top sections, and then the remaining oil was flooded by horizontal pressure of ASP flooding conducting at the bottom sections, thus realizing 3-dimensional flooding.
Gas injection for stable gravity combination flooding may provide a viable option for EOR after polymer flooding. The method of this paper will provide the necessary support for future applications.
Effect of Gas Adsorption on Pulse-Decay Permeability Measurements
Authors: Eliebid Mohammed , Mahmoud Mohamed , Al-Yousef Hasan Y. , Elkatatny Salaheldin , Al-Garadi Karem 
Published: October 2018

Abstract
Pulse-decay method is a technique used to estimate cores permeability using gas injection based on Darcy's flow model. Helium and nitrogen are generally used when the target formation is an oil formation or liquid permeability is sought. However, new approaches suggest using CH4 to avoid correcting for properties difference between the testing fluid and reservoir fluid. This study focused on the latter approach to quantify the correction to gas adsorption. The Cui et. al, model based on Langmuir adsorption isotherm is modified to Cui-Freundlich isotherm which has been proven adequate to fit the adsorption on intact reservoir rocks. The model is developed using gas and rock properties and the approach is generalized by using reduced pressure and temperature to account for the gas compressibility. The results of the modified model showed that the new model can capture effective porosity of adsorption ϕa used to correct the pulse-decay storage capacity parameters a and b. This correction in the storage volume and rock porosity values will enhance the permeability estimation in the ultra-tight rock samples.
Novel Downhole Technology With a True Point-the-Bit Rotary Steerable System Delivers Significant Operational Improvement and Cost Savings in a Challenging Reactive Shale Formation: Case Study, Kuwait
Authors: Marafi Abdulla Abdulkarim , AL Mulafy Mohamed , Sekhri Anish , Iqbal Hussan , Ebrahim Al-bateni , Farhi Nadir , Ghoneim Mohamed , Samie Mohamed , Hamida Malek Ben , Khirfan Mohamed 
Published: October 2018

Abstract
In pursuit of higher oil production targets in North Kuwait, a major campaign was initiated to drill reentry and new horizontal wells targeting a major multilayer carbonate reservoir. A recent study established that horizontal drilling along the northeast/southwest plane is most favorable to cut through two major unstable shale layers. Most well profiles did not satisfy this condition, given the subsurface target and the nearby wells. Contradictory to the study recommendations, multiple directional wells had to cut toward the least stress direction, complicating the tripping capability, spending many hours on back reaming to get the bottomhole assembly (BHA) out of the hole. The requirement for a reliable passive reaming device became necessary for less time-consuming trips.
This paper discusses a review of a downhole technology that has helped improve metrics against this time-reduction imperative. Multiple designs comprising additional string stabilizer(s) did not address the issues resulting from placement too far from the BHA or not having reaming capabilities. In collaboration with a specialized downhole tools supplier, the service company designed a wired rigidized heavy-duty inline stabilizer (ILS) and a bidirectional passive cutting structure compatible with the rotary steerable system (RSS) BHA requirements, replacing the existing conventional wired ILS placed within the logging while drilling (LWD) tool string. This helped the reamer device be close to the RSS to provide the necessary BHA stabilization while delivering enhanced wellbore quality through controlled reaming and back-reaming capabilities. Using this engineered stabilizer contributed to helping ensure a gauged hole by removing tortuosity, ledges, microdoglegs, and spiral patterns associated with directional drilling.
The proposed reamer device RSS BHA was successfully run on multiple wells where the shale portion became active while pulling out of the hole (POOH). The dedicated bidirectional passive reaming features above the RSS enabled reaming while drilling and back reaming the hole without any difficulties and removed obstructions more easily and efficiently. Reducing tripping time and protecting expensive BHA components from damage were a direct benefit of using these reamers. One well achieved a benchmark rate of penetration (ROP) because of a smoother running speed and weight transmission improvement. With the integration of the reamer device, the reaming process could be implemented without affecting building capability of the point the bit RSS with a build rate of more than 12°/100 ft achievable when necessary.
Improving Reservoir Heterogeneity Prediction and Well Placement by Interim Seismic Acoustic Impedance Inversion
Authors: Mahgoub Mohamed , Narino Alfredo , Badri Abdelmoneim 
Published: October 2018

Abstract
Improving seismic data quality prior to acoustic impedance (AI) inversion is one of the main challenges for interpreters. Proper reprocessing of seismic data may attenuate most of the noise and multiples but it can be costly and time-consuming. Therefore, while data reprocessing is in-progress, an interim solution is implemented to enhance 3D seismic quality. The solution was an effective data conditioning workflow that significantly improved seismic quality for satisfactory inversion results. Having achieved acceptable seismic data quality, we inverted the seismic volume to estimate acoustic impedance. A seismic porosity model is transformed from this acoustic impedance and used for reservoir heterogeneity prediction and well placement. The analysis indicates that the wavelet equalization is a very useful tool for stabilizing the wavelet phase and amplitude spectrum in the study area. To ensure stability of the seismic wavelet at well locations, wavelet extraction is performed before and after wavelet equalization. The structural and stratigraphic interpretation is significantly improved by inverting the conditioned seismic data to relative acoustic impedance (RAI). The acoustic impedance estimates is validated by comparing them with well log values. This validation is essential to quantify the depth conversion and to provide optimum guidelines for drilling/geo-steering. Therefore, the final acoustic impedance inversion is showed good correlation with well log data. The inversion results are successfully used to position new horizontal wells in the study area. Our experience revealed the importance of acoustic impedance inversion in guiding geo-steering wells, particularly in heterogeneous reservoirs. However, the limitation of vertical seismic resolution remains the main challenge. The study provides best practice of seismic data optimization by stabilizing wavelet phase before inversion. Ultimately this improved our ability to position horizontal wells in heterogeneous reservoirs.
Successful Applications of a Novel Compound Lost Circulation Additive with Variable Structure
Authors: Zhu Qi , Wang Yong , Zhang Yongqing , Wang Zhifa , Wang Zhaohui , Liu Chao 
Published: October 2018

Abstract
Lost circulation is a complicated situation in the drilling operation, wasting a lot of time and mud during processing. A serious lost circulation can cause many hazards, such as internal pressure drop, affecting normal drilling, causing well instability, inducing formation fluid into wellbore and blowout. The current plugging technology can solve some of lost circulation leakage, but there are still some problems in conventional plugging technology, such as particle size of plugging material does not match crack width, slippage of plugging material in blocking zone, and weak adhesion of plugging material additive to reservoir, which restricts the success rate of lost circulation plugging operation.
Variable structure has variable network affected by stress compound with elastic plugging material forming a plugging mixture for different leakage speed and crack width.
The rigid plugging materials with different particle sizes and different materials are mixed in a certain proportion to form a compound plugging agent for different leakage speeds and different leakage crack widths. Combined with the variable structure gel, a new type of lost circulation plugging system is used to seal the fracture-cavity reservoir leakage.
Through indoor experiment simulation, the on-site plugging formula which is suitable for fracture- vug reservoir under different temperature is formed and determined.
Scanning electron microscope shows the compound plugging mixture (CPM) has a variable network structure. Solution experiments show CPM is not diluted with water. Single plugging gel can plug 0.04-0.8 mm cracks and pressure capacity is greater than 3 MPa. With different types and sizes rigid plugging materials and elastic plugging material can block crack width of 0.15-5mm and pressure capacity is greater than 7.5MPa.
The novel CPM material has been tested and used for more than 50 wells. The porosity or micro- fracture leakage and the leakage rate of less than 30m3/h, the success rate of plugging is up to 100%, and the loss rate between 30 and 60m3/h, the success rate of plugging is beyond 85%. And the leakage rate of more than 60m3/h, the success rate of plugging is more than 80%.Leakage loss time is less than 80% shorter than conventional plugging technology.
Waterflood Management Using Streamline-Based Inter-Well Flux Information and Classical Finite Volume Reservoir Simulation
Authors: Tian Changbing , Lei Zhengdong , Zhu Zhouyuan , Chen Zhangxin , Li Lei , Wang Wenhuan , Peng Huanhuan , Tao Zhen 
Published: October 2018

Abstract
In this work, we implement new software for improved waterflood management by combining classical finite volume reservoir simulation together with streamline tracing and corresponding inter- well flux evaluations to optimize waterflood performance. We show reduced water cut and improved oil recovery by using streamline-based flux information to adjust well rates, while retaining the advantages of rigorous finite volume simulation.
We have introduced two basic modules here: a commercial reservoir simulator Eclipse and our own streamline tracing and waterflood management program. Waterflood simulation is performed for a certain time span until simulation is paused and the streamline tracing program is called to calculate inter-well fluxes and adjust new well rates for better waterflood performance. The simulation continues afterwards until the next tracing and adjustment point is reached. The two modules work iteratively. The streamline tracing program uses the classical Pollock's tracing method. It is designed to trace streamlines on a compressible velocity field and a general corner point grid system with non- neighboring connections. The new injection rates are adjusted according to each well's injection efficiency calculated from inter-well fluxes as proposed in previous works.
Our waterflood management program successfully works cooperatively with the commercial simulator, with data transfer realized by making the simulator to output the velocity field and other information into restart files. Streamline tracing is performed successfully not only on simple geometry corner point grid cases, but also on heavily-faulted realistic reservoirs under waterflood. Streamline- based inter-well multi-phase fluxes are calculated, in which the injection efficiencies are derived accordingly. Injectors with higher efficiencies will receive more water from the source, according to the injection allocation algorithms and vice versa. After re-adjusting injection rates multiple times during the simulation, we typically observe a reduction in field water cut of up to 5% and an increase in oil recovery in our test cases. Inter-well flux information serves as effective diagnostic tools to identify injector-producer pairs with large amount of water cycling. All simulations conducted here are rigorously finite volume based, which takes into account the full physics of non-advective processes such as gravity and capillary effects.
In conclusion, we have implemented a streamline-based waterflood management program which works iteratively and cooperatively with a commercial reservoir simulator, without switching to streamline simulation. It provides an effective solution for improving oil recovery in brown fields by combining the rigorous mathematical nature of finite volume simulation and the power of streamline- based flood management.
Multiple Scenarios Integrated Upscaling With Full Tensor Effects of Fractured Reservoirs
Authors: Tian Changbing , Lei Zhengdong , Li Junchao , Yuan Jiangru , Hao Yinquan , Zhu Zhouyuan 
Published: October 2018

Abstract
Heterogeneity of the fine-scale models will result in full tensor effects for the upscaled models, especially in reservoirs with channels or fractures. A flow-based upscaling approach integrating multiple flow scenarios is developed to effectively capture the full-tensor effects when upscaling from fine-scale discrete fracture models. The new approach is proposed to deliver computationally affordable simulation models under precision comparable to the high-resolution models.
The approach starts with several sets of flow-based single scenario upscaling procedures. A fine-scale discrete fracture model is built up as the reference model for all the successive procedures and comparisons. Then several flow cases (referred as scenarios) are determined according to the target simulation conditions. A global upscaling technique under multipoint flux approximation scheme is introduced to each flow scenario. An integrated output least squares method, which aims to minimize the total bias of simulation results of all the flow scenarios, is adopted to obtain the optimal transmissibility connection list of the coarse-scale models.
We design and implement several examples including two synthetic conceptual cases and a real field case. In each case, comparisons are provided for the simulation results of the proposed approach and previous upscaling approaches based on two point flux approximation schemes. The coarse-scale models upscaled by different methods are based on the same fine-scale (reference) model in each case. The results of the upscaled models are also compared to the reference model. The numerical results show that the new approach generates coarse-scale models which are closer to the fine-scale model. Although under certain conditions, traditional upscaling methods can achieve equivalent results, it is proven that the new approach is more robust when applied to more general flow scenarios. It can be noted that it may take a bit more time for the numerical simulation of coarse-scale models upscaled by the new method, due to the introduction of the non-neighbor connections. When compared to the fine- scale model, however, the improvement of computational efficiency is still pretty significant. The last case is a real field case with about 500,000 fine-scale grids and 10,000 coarse-scale grids, which demonstrates the ability of the new approach to be applied in the industry.
The novelty of the proposed approach is the optimization technique integrating multiple scenarios to generate a high precision coarse-scale model under multipoint flux approximation scheme. The new method effectively capture the anisotropic features of the coarse-scale models, which is a challenge for flow-based upscaling procedures because a single flow simulation is usually inadequate to obtain full tensor information of the upscaled models.