bluuebunny/crossref_metadata_2025_split huggingface dataset:
Integrating Geological Characterization and Historical Production Analysis to Evaluate Interwell Connectivity in Tazhong1 Ordovician Carbonate Gas Field, Tarim basin
Authors: Hedong Sun , YanMei Xu , Xingliang Deng , Jianfa Han , Ying Shi , Linlin Lu , Wen Cao 
Published: September 2011

Abstract
Tazhong No. 1 gas field is a typical vug-fractured carbonate gas condensate reservoir with high heterogeneity and complex geological characteristics. This reservoir was discovered 5 years ago. There is an urgent need to study inter-well connectivity procedures for maximum oil /gas recovery. A detailed geological understanding of the reservoir is needed to gain a detailed reservoir dynamic description and determine the optimal recovery method for this oil reservoir. These are essential to having a successful operation, as well as reducing drilling uncertainties and improving the efficiency of oilfield management. An integrated static and dynamic workflow to determine connectivity is developed with the data collected from initial production stages of over 20 wells. This paper presents the concept of dynamic characterization of the vug-fracture carbonate gas condensate reservoirs, which mainly involves data processing, wellbore flowing pressure calculation, analytical well test analysis, numerical well test analysis, long-term production data history match and decline curve analysis, and performance prediction. In addition, the authors introduced history matching and pointed out the main reasons for the significant errors between actual data and simulation results. Several examples of triple medium condensate gas filed are given. Reservoir properties, such as permeability, skin factors, are determined. Reservoir volume and OGIP are estimated. These integrated dynamics results served as input data for connectivity with geological characterization. The results also show that the methodology is necessary, which can accurately identify gas reservoir parameters and decrease the non-unique. Based on the reservoir dynamic characterization, the wells network locations are optimized and good results are obtained in oil recovery.
Review on ESP Surging Correlations and Models
Authors: Gamboa Jose , Prado Mauricio 
Published: September 2011

Abstract
Head deterioration observed in electrical submersible pumps under two-phase flow is mild until a sudden performance breakdown is observed in the pump head curve at a certain volumetric gas fraction. This critical condition is termed surging. Consequently, the two-phase pump head is associated with whether the stage operates under conditions prior (mild performance deterioration) or after (severe performance deterioration) the surging point.
The surging, for engineering purposes, can be predicted by published correlations, but the lack of theoretical basis is a limiting factor for their application. Mechanistic models seem to be the proper alternative. But, the poor understanding of the physical mechanism that causes the surging hinders the development of such mechanistic models. This paper reviews some of these correlations and mechanistic models by comparing its predictions against experimental data acquired in a closed loop with water and air utilizing a commercial 24 stages ESP. The data cover a wide range of volumetric gas fraction, rotational speeds and intake pressures. As consequence of this analysis, two correlations have been formulated. The first correlation predicts the surging as function of rotational speed and fluid properties, while the second correlation intends to predict the homogenous boundary. This boundary encloses a regime in which the homogenous model works for predicting the ESP head curve.
Fully Coupled Chemical-Thermal-Poro-Mechanical Effect on Borehole Stability
Authors: Zhai Z.. , Abou-Sayed A.. 
Published: September 2011

Abstract
Drilling instability is always one of the major challenges to drilling engineers. The temperature differential and pressure differential affect the borehole instability by altering the stress concentration at near wellbore region through poro-elastic and thermal elastic stresses. The temperature gradient and pressure gradient between the drilling fluid and formation change not only from conduction and convection, but also from interacting to each other. In low mobility formation such as shale, the thermo-induced pore pressure is important while in high mobility formation, the pressure effect on the temperature is not negligible.
Furthermore, the imbalance in chemical potentials between the formation pore fluid and wellbore drilling fluid will cause the solvent and solutes to diffuse and transport. This will alter the fluid pressure due to chemical osmosis pressure. In this paper, a fully coupled borehole stability model is proposed including thermal, pore, chemical effect. In the model, not only pressure, heat conduction and convection are included, but also the interaction of pressure and heat are incorporated. The model is solved by superimposing method and finite difference method which otherwise is impossible to be obtained from analytical solution.
A Novel Fluid to Improve the Hydraulic Cracking Stress of Rock
Authors: Grady Brian , Wu Shuqing , Funkhouser Gary P. 
Published: September 2011

Abstract
Negatively charged poly(methyl methacrylate-co-butyl acrylate) (P(MMA-BA)) particles, and positively charged dissolved poly(ethyleneimine) (PEI) polymer were adsorbed onto a cement block using a layer-by-layer assembly technique. The block was fashioned so as to have a cylindrical hole running from one face to another along its long axis, and a fluid containing one of the two charged materials was pumped through the block. The result was a controllable-thickness film tens of micrometers thick, and the pressure required to crack the cement block was measured after sealing one end of the hole. Latex particles with a Tg near the use temperature showed the maximum improvement in the cracking stress of the blocks. In a multilayer coating with identically sized particles, the cracking stress of the blocks increased to an improvement of 25% and then dropped off with increasing number of layers, even though the relationship between film thickness and the number of layers was linear. An improvement of about 30% in the cracking stress of the coated blocks was obtained when using multiple layers with different particle sizes. Tests done under confinement, e.g., with an external stress applied to the outside of the blocks, suggest that not only does a film-forming mechanism contribute to performance, but filling of microcracks in the rock may also play a role.
Viscosification-on-Demand: Chemical Modification of Biopolymers to Control Their Activation by Triggers in Aqueous Solutions
Authors: Reddy B. R. 
Published: September 2011

Abstract
Completion and stimulation operations in the oilfield industry are made possible because of the availability of suitable viscosifying polymers, particularly those from biological sources. Many such polymers, particularly those of random-coil type, suffer from viscosity losses caused by thermal thinning at elevated temperatures. Shear thinning coupled with thermal thinning of natural polymers and their derivatives limits their use to lower temperatures or requires high concentrations of such materials to prevent particulate settling. High polymer concentrations cause excessive surface-fluid viscosities. High surface viscosities of fluids require high pump pressures, which can result in either operational limitations or wellbore instabilities. An ideal way to overcome such limitations is to compensate for thermal thinning as it occurs by delaying release of viscosifying polymers into the treatment solutions until needed.
This paper discusses the development of a simple and cost-effective chemical method used to modify polysaccharides and their derivatives such that their viscosification ability, by hydration followed by dissolution in the treatment fluid, can be triggered when and where it is needed. The triggers can be salinity, pH, and/or temperature. Additionally, the method also provides for improvement of viscosification efficiency of the polymers because of increased molecular weights of the modified polymer, which allows fluid designs with less polymer content, resulting in less formation damage. Using this method, guar and its derivatives, cellulose and its derivatives, starch, xanthan, scleroglucan, and diutan polymers were modified to obtain products with interesting and versatile combinations of delayed hydration, higher viscosification efficiencies, and susceptibility to different methods of activation. The timing of viscosification using different triggers was measured by viscosity/rheological methods. Potential uses for such materials in fracturing, gravel packing, fluid diversion, and plugging are demonstrated with suitable examples. Mechanistic aspects of the chemical reactions are also discussed.
The Impact of Organic Acid on Scale Inhibitor/Corrosion Inhibitor Interaction, a Case Study from West Africa
Authors: Spicka K. J. , Johnston C. J. , Jordan M. M. , Nguyen L. T. , Samaniego S. L. , Sutherland L. 
Published: September 2011

Abstract
A development in deepwater off Western Africa has been experiencing incompatibility between the incumbent scale inhibitor and a newly deployed corrosion inhibitor. Initial laboratory testing to determine the amount of scale inhibitor necessary to overcome the interference from the corrosion inhibitor indicated that the effects of the corrosion inhibitor could not be overcome by increasing the dose of the scale inhibitor. Testing of other scale inhibitors indicated that there was not a suitable scale inhibitor that could inhibit scale formation in the presence of the corrosion inhibitor. That initial work was performed using synthetic brines that contained no acetate/acetic acid buffer to help control pH of the system. Further work evaluating the effect of buffering upon scale inhibitor performance employed brine containing an acetate/acetic acid buffer. Once this buffer solution was employed in static bottle testing, it was observed that an alternative scale inhibitor previously tested now worked in the presence of the corrosion inhibitor. While it is known that corrosion inhibitors can impact scale inhibitor performance the impact of organic acid on this interaction has not been published.
Since the field where the chemicals were to be applied is known to contain organic acids (upwards of 2,000 ppm), the testing which included the acetate/acetic acid buffer is viewed as a more representative test for the field than the testing that did not contain any organic acids. A field trial of the alternative scale inhibitor and the corrosion inhibitor has been under taken. The paper will present the results from two field trials, the laboratory evaluation to understand the mechanism of interaction and selection of the alternative inhibitor chemical. This paper will shed light on the challenging subject of scale inhibitor and corrosion inhibitor interaction and review the most appropriate test methods/conditions to select non interfering chemicals.
Evaluation of Liquid Loading in the Pinedale Field: Integration of Smart Plunger Data and Mechanistic Modeling
Authors: Bello O. , Falcone G. , Xu J. , Scott S. , Harrod J. 
Published: September 2011

ABSTRACT
Smart plungers1 can be used to enhance diagnostics and performance evaluation of liquid-loaded gas wells. The objective of this work is to develop a framework in which surface measurements and smart plunger data from the Pinedale field are analyzed using a mechanistic plunger lift model, so as to provide a methodology for maximizing well performance and reducing operational costs.
In this paper, the application of smart plunger technology in two Pinedale wells is presented. A description of the mechanistic model used for the analysis of the gathered transient flow data is also provided, including a discussion on changes to the model for different well completions (namely with or without packer). Inputs to the model are dynamic pressure and temperature, well completions, fluid properties and produced flow rates. Results from the two Pinedale wells are presented and critically reviewed. The results suggest that the proposed integrated approach is a feasible and practical methodology to optimize the performance of plunger lift cycles. Recommendations are then made for future technological advances in the development of an interpretation model for real-time analysis of smart plunger data, towards fully automated management of liquid loading in gas wells.
Monobore Expandable Liner Extension Saves Well With Problematic Drilling Programme from Abandonment
Authors: Stockmeyer Carl F. , Durment Albert S. , Ismail Ahmed S. , Lapeira Manuel 
Published: September 2011

Abstract
To circumvent or minimize non-productive time (NPT) in wells where drilling programs with problematic drilling sections would be expected, the Monobore Expandable Liner Extension System (MELES) was developed. A recent exploration project in Egypt predicted costly and time consuming drilling hazards in their well programme and planned the MELES as a contingency system should these situations be realized. While drilling the 12.25-in. hole section below the 13-3/8-in. casing, situations with caving, sloughing, and swelling shale sections, combined with lost returns were encountered. Before the 12.25-in. hole section was completed, shales packed off the drillstring and part of the bottomhole assembly (BHA) was left in the hole. The MELES was no longer a contingency, but would now be required in the casing design to reach the target evaluation depth with a sufficient hole size of 6.0-in. Casing (9-5/8-in.) was run as deep as hole conditions allowed, with a recess shoe to enable the monobore expandable liner extension below. Following drillout of the recess shoe, open hole conditions presented the same challenges previously experienced. The 8-in.outside diameter (OD) liner extension system was run, but well conditions prevented getting the expandable liner to depth and it was pulled out of the hole.
Conditioning trips with increased mud weight up to 12.3 pounds per gallon (ppg), reaming and backreaming, along with an open hole cementing effort, were performed for stabilization. A second attempt was made to run in the hole. The hanger located in the recess shoe profile of the 9-5/8-in. casing and the system was expanded to the same inside diameter as the casing above. The expanded liner's shoe was now located just above the previously left BHA, but the trouble zone sections were isolated with no reduction in hole size from the previous casing.
The expanded liner was pressure tested to 1,000 psi before cementing. Recess shoe ports were enabled and initial circulation established, and the wellbore did indeed pack off and build pressure, preventing full annular cement. Pressure inside the casing was applied and 15 barrels (bbl) of cement were squeezed into the hole. A casing exit was milled in the expanded monobore liner to enable bypassing the BHA that was left in the hole from previous drilling operations.
The case history explored in this paper highlights overcoming substantial issues using expandable drilling liner technology via a monobore liner extension that resulted in successful installation and circulation. The preplanning, installation considerations, expansion process, lessons learned and post-deployment results will be discussed.
The Use of Zinc Dialkyl Dithiophosphate as a Lubricant Enhancer for Drilling Fluids Particularly Silicate-based Drilling Fluids
Authors: Chang Zen-Yu , Breeden David , McDonald Michael 
Published: September 2011

Abstract
As well profiles become more challenging, drilling fluids and lubricants face the need to provide further reductions in torque and drag. Tightening environmental regulations have placed further pressure on operators who now look more frequently to water-based fluids to solve these challenges despite their higher coefficients of friction.
One of the most commonly used methods for reducing torque and drag is the addition of a lubricant to the drilling fluid. Lab results show that the addition of a minor amount of zinc dialkly dithiophosphate (ZDDP) is an effective means of improving the performance of most classes of lubricants including those used with water-based fluids. Downhole conditions of temperature and pressure can provide the necessary conditons for the ZDDP to decompose and form a polyphosphate film on the surface of the drill string and casing. It is postulated that this film serves multiple beneficial roles; reducing wear and corrosion on the underlying metal surface while working synergistically with other lubricants used.
This paper focuses on the use of ZDDP/lubricant combinations in potassium and sodium silicate-based drilling fluids. Silicates were chosen as the drilling fluid for this evaluation because of their reputation for shale inhibition, clean environmental performance and because these fluids are often disadvantaged with high coefficients of friction. Lab testing has shown that a small addition of ZDDP can improve performance for a number of lubricants demonstrated by 15% to 60% reductions in coefficient of friction versus the unmodified lubricant. Of the various lubricants tested with ZDDP, the base lubricant was selected for field trials using the criteria of performance and health, safety and environmental characteristics.
Effect of Alkalinity on Oil Recovery During Polymer Floods in Sandstone
Authors: Kazempour Mahdi , Sundstrom Eric , Alvarado Vladimir 
Published: September 2011

Abstract
Alkaline flooding has been purported as a promising process for enhancing heavy oil recovery, while alkaline-polymer (AP) and alkaline-surfactant-polymer (ASP) injection represent commercial flooding strategies for lighter oils. The alkali in an ASP flood can reduce adsorption of surfactants and react with acids in the oil to form soaps. Polymers increase the viscosity of water and control mobility ratio. The addition of an alkali to a straight polymer flood can further increase the efficiency in polymer flooding. The alkali can react with the rock and polymer to reduce polymer adsorption and decrease polymer solution viscosity allowing higher injectivity.
We report results of core experiments for polymer, alkali, and AP tertiary floods. The conditions tested correspond to Wyoming's Minnelusa sandstone reservoirs. Berea cores were waterflooded to residual oil saturation, and then a tertiary injection of a polymer, alkali or AP solution was run, followed by waterflooding. We also show results of polymer solution viscosity with varying alkali concentration. Polymer adsorption results from dynamic and static experiments with and without alkali are reported. Numerical history match of coreflooding results was performed using k-partition method using CMG-STARS.
Results show that a tertiary alkali injection produces negligible oil recovery and pressure drop increase. Straight polymer injection produces considerable oil recovery with a significant increase in pressure drop that may not be favorable for field designs. The injection of the AP solution also produced considerable oil recovery, but the increase in pressure drop was less than that of the straight polymer flood. The effects of alkali on polymer and rock surface lead to significant impact on recovery factor, resistance factors and also residual resistance factors.
Results of this study can be utilized to improve the engineering design of polymer flooding with the addition of alkali to improve the injectivity and reduce the loss of polymer due to adsorption on the rock surface.
Critical Evaluation of Biocide-Friction Reducer Interactions Used in Slickwater Fracs
Authors: Aften Carl , Paktinat Javad , O'Neil Bill 
Published: September 2011

Abstract
The practice of slick water fracturing has increased significantly with the advent of horizontal shale stimulation. Many technologies have evolved to improve the practice, including multi-stage fracturing of horizontal wells and simultaneous fracturing, both of which increase frac treatment volumes up to several million gallons of slick water per well. Recent incidents related to interaction of biocides and friction reducers have created concerns for the industry and compelled operators to adopt methods of using biocides with short half-lives, in order to minimize or eliminate biocide contamination in flowbacks reused as frac water. Concurrently, some biocides can crosslink polyacrylamide-based friction reducers, causing severe formation damage, production impairment, and flowbacks that contain cross linked polymers, requiring further chemical treatment and increasing operational costs.
This study examines polymers and biocides, along with other additives (oxygen scavengers and scale inhibitors) commonly used in slick water fracturing, and identifies the parameters that could minimize the effectiveness of slick water frac treatments and potentially cause formation damage. To illustrate, this study incorporates a high molecular weight water-based emulsion polyacrylamide as the friction reducer, used in conjunction with various non-oxidizing biocides, with results reflecting positive, negative, or neutral impacts. Experimental results presented in this study are supported by utilizing a 20-gallon capacity friction loop with a Reynolds number of 150,000. Conventional bench top methods were also used. Results indicate that particular biocide-friction reducer systems exhibit significant performance deviations when standard brines or flowback water is used in shale slick water fracturing treatments.
Results obtained from this study provide operators a tool to avoid combinations of specific chemicals used in slick water fracturing. Awareness of additive interactions in specific frac fluids used can maximize the effectiveness of treatments, and avoid costly errors that may adversely impair production and jeopardized performance of the biocide. The integrity of the assets on location are thus affected by diminished biocide performance (Olliver et al, 2005). Therefore, any biocide chosen for slick water treatment should be pretested for compatibility with the friction reducers and other chemical additives, in order to insure an incident free operation from a chemical standpoint and minimize the potential for formation damage.