bluuebunny/crossref_metadata_2025_split huggingface dataset:
Case Study: Analysis of the Characteristics of the Damage to Dujiatai Low-Permeability Reservoir by Water Injection and Research of Damage Removal Methods
Authors: Zhengchao Zhao , Wei Liu 
Published: February 2008

Abstract
Dujiatai reservoir has an oil bearing area of 37.2km2 with the OIP of 2409×104t, burial depth of −2650∼-2960m, porosity of 15.1% and permeability of 37.7×10−3µm−2. In general, the reservoir is produced initially under natural energy by elastic drive and solution gas drive and development with water injection is tested in the later stage due to fast pressure decline and subsequent substantial production decline.
During the water injection field test, although the water to be injected had been filtered to a fine degree, the water injection pressure increased substantially after a short time and water injection became difficult and some of the injectors were forced to be shut in because no water could be injected.
The paper introduces the analysis results of the tests on water injection damage to Dujiatai low permeability reservoir. (1) Solid particles entered the reservoir, forming blockage due to the small throats of filtration with the average radius of the throats of about 1.0μm; (2) Because the injected water was not treated against swelling, clay swelled, forming blockage due to the medium to strong water sensitivity of the reservoir; (3) Because of the medium to strong velocity sensitivity of the reservoir, fine particles staying in a unconsolidated manner on the borehole walls or inner surface of the base rocks fell out, migrated and piled up at the throats, forming blockage; (4) The scaling tendency of CaCO3 of the injected water was obvious and the scales adhered to the inner surface of the throats, reducing the filtration radius of the throats; (5) The water injection pipeline was corroded seriously and the suspended particle content at the outlet of the filtering station reached the standard, but it exceeded the standard after going through the water injection pipeline and reaching the wellhead and it was even worse when it reached the bottom of the well.
The solutions for the water injection damage to Dujiatai low permeability reservoir are as follows. (1) Acidization or acid fracturing deeper into the formations with weak acids is conducted to erode the unstable migrating particles; (2) Antiswelling agent is added to the injecting water to reduce clay swelling; (3) A secondary filtering unit is set up at the wellhead or the water injection pipeline is replaced with a corrosion prevention pipeline lined with fiberglass.
Through-pump Stimulation: A Cost Effective Alternative
Authors: Ojukwu K. I. 
Published: February 2008

Abstract
Electrical submersible Pumps (ESPs) have been employed for decades in accelerating oil production and creating pressure head needed to produce sub hydrostatic wells. ESPs are installed downhole and comprise stages of impellers driven by electrical motors that are automatically cooled by the passing fluid.
A major disadvantage of ESPs is blocking access to well re-entry for surveillance and through-tubing intervention. One of such cases is during acid stimulation. In Petroleum Development Oman (PDO), acid jobs have been carried out as part of workovers to retrieve the pumps first. The cost implication can be tremendous ranging from $250,000 to $400,000.
Two deployment techniques were adopted in PDO recently by bullheading acid through ESP and Coiled Tubing (CT) into the reservoir and by so doing, saved 80-93% of comparative cost. The techniques involved the use of abrasive resistant ESP for vertical wells and ESP bypass (Y-Tool) for CT deployment in horizontal wells. The challenges of using these techniques include damaging the ESP with acid or mistakenly circulating acid via the tubing-casing annulus. We have been able to apply these techniques successfully in acidizing a sub hydrostatic carbonate reservoir. In one example, new vertical well was stimulated to enhance matrix withdrawal from 20m3/d (120bbl/d) to 128/d (790bbl/d) dry oil and in another example, a new horizontal well which was severely damaged by high viscous pill was stimulated via CT. These have opened new opportunity for matrix well withdrawal in this reservoir.
This paper presents examples of candidate selection, cost justification, pump selection and acid recipe. It also illustrates the innovative deployment techniques used to prevent pump & tubular damage as well as achieving proper acid placement into the reservoir. These examples can be treated as best practice worth replicating in all ESP applications worldwide.
Benefits of a p-3D Over a 2D Model for Unified Fracture Design
Authors: Economides Michael J. , Demarchos Andronikos 
Published: February 2008

Abstract
Almost all commercial hydraulic fracture models are simulators that use injection variables such as fluids and proppants to predict fracture geometry. Totally different in both philosophy and approach are fracture design models which are aimed to first determine the optimum fracture geometry to maximize production (or injection) and then to establish the best way to achieve the desired geometry.
Starting with a treatment schedule, and with fracture mechanics, fluid mechanics and rock mechanics modeling of varying degrees of sophistication, fracture simulators predict the fracture geometry. While these models were originally using the classic 2D models they have evolved into pseudo-three-dimensional (p-3D) and, even, in some cases, fully three-dimensional (3D) models.
The same models are used to match the observed pressure in the field and because usually the original intent was to match net fracturing pressure they have incorporated among other things, near-wellbore tortuosity and tip-propagation effects, adding further dimensions of complexity. At the same time they provide facility to adjust their predictions with actual pressure measurements. Whether this multi-adjustment capability leads to better understanding of phenomena is another matter.
The most serious deficiency of most industry models is that they do not provide for optimum fracture performance from a production engineering point of view. They try many "proppant schedules" until one appears the "best". Clearly such ad hoc approach is flawed and statements such as "maximizing conductivity" still torment the industry.
We have a different approach. We use the Unified Fracture Design (UFD) theory to pinpoint the optimum fracture dimensions and then use our p-3D model to allow for the necessary injection. The main benefit of our p-3D approach is to account for constraints, real reservoir configurations and heterogeneity. The use of p-3D models in a design-driven fracture simulation is recommended with the resulting fracture geometry satisfying all elements that other p-3D models can do but, far more important, the geometry thus derived is exactly the one that can maximize well productivity.
Wettability Alteration at Elevated Temperatures: The Consequenses of Asphaltene Precipitation
Authors: Escrochi M. , Nabipour M. , Ayatollahi Sh. , Mehranbod N. 
Published: February 2008

Abstract
Asphaltenes are undoubtedly one of the important difficulties in the oil industry; its precipitation can impose specific affects on the productivity of the producing zone, as well as in the surface facilities and transportation lines. The main in situ consequences are their effect on the permeability by pore blockade, and on the wettability alteration by surface precipitation. In this paper, thermally induced wettability alteration is studied experimentally. The changes in the rock mineral content after imposing heat as the effect of thermal oil recovery are also studied using XRD. The results verify that asphaltene precipitation could be considered as the main platform for wettability reversal and the permeability reduction in the treated zone. The results also clarify the contradictory doubts around wettability alteration during thermal treatment in the literature. The experimental data shows that the media is gradually altered to strongly oil-wet in the temperature range of 150 – 400°C and subsequently changed to water-wet as the temperature increased.
Furthermore, the effects of temperature on asphaltene destabilization and precipitation is studied and the required thermodynamic criterion for asphaltene precipitation is found. The asphaltene precipitation in the formation by the thermal oil recovery techniques is thermodynamically modeled using regular solution theory.
The simulated date obtained using the model verifies by the experimental results. The model shows that as formation temperature increases toward crude oil's bubble point, its molar volume increases and solubility of the asphaltene decrease. This leads to asphaltene precipitation, and alteration of wettability toward strongly oil-wet condition. At temperatures higher than the crude oil bubble point, precipitated asphaltene start to dissolve, mainly due to evaporation of crude oil saturates. This stimulates a wettability shift toward more water-wet condition.
Mechanisms, Parameters, and Modeling of Naphthenate Soap-Induced Formation Damage
Authors: Sarac S. , Civan F. 
Published: February 2008

Abstract
The naphthenate soap deposition and related formation damage in petroleum reservoirs are investigated by means of the laboratory-scale experimental and theoretical studies. Experiments were carried out in three directions to understand and quantify the naphthenate soap deposition problem. Static bottle tests were conducted to determine the precipitation rate for various pH and temperature conditions. Microscopy investigations were carried out to verify the growth of naphthenate soap particles under different pH conditions. Core flow tests were conducted to generate naphthenate soap particles and to determine the permeability impairment caused by subsequent deposition of these particles in porous media under flowing conditions and different pH values. A power-law expression was proposed and verified for the precipitation rate of the naphthenate soap particles. The parameters of the rate equation were correlated with respect to pH and temperature. This also allowed the determination of the critical pH value for the onset of naphthenate soap precipitation. The results of the particle size experiments were described by a particle growth equation and the parameters of the equation were correlated with respect to pH. The core flow experiments proved the occurrence of formation damage caused by naphthenate soap precipitation and subsequent deposition. The permeability impairment in core flow experiments was described by a new differential model. The applications presented in this study provide insights for understanding of the mechanism and magnitude of naphthenate soap-induced formation damage, and help in taking proper measures for avoiding the formation damage caused by naphthenate soap deposition.
Potential Damage Due to Relative Permeability Modifiers: Laboratory Studies and A Case History
Authors: Al-Taq Ali A. , Nasr-El-Din Hisham A. , Saudi Mohammed M. , Sierra Leopoldo 
Published: February 2008

Abstract
Relative permeability modifiers (RPM), hydrophobic in nature, are used to selectively reduce permeability to water with minimum impact on permeability to oil. Lab studies and field application reveal that RPM polymers, in some conditions, may damage the permeability to oil resulting in reduction/ or lost of oil production.
Single and parallel core flow tests were conducted on carbonate and sandstone cores at reservoir conditions. Single core flow tests showed that RPM polymers can damage tight cores (less than 1 md) by forming an external filter cake on the injection face of the cores. Accumulation of RPM polymers at the face of the core means that these chemical will not properly propagate inside the core, which significantly reduces their ability to minimize water production.
Parallel core-flood experiments conducted at reservoir temperature (200°F) showed that RPM damaged the permeability to oil when there was a large permeability contrast (greater than 1:5) in favor of the oil-saturated core. Due to the high permeability contrast, most of RPM polymer solution preferentially entered the oil-saturated zone, thus damaged the oil production zone. Field data supported lab findings and showed that oil production of an oil well dropped significantly following RPM polymer treatment. It was found that polymer injection rate was a key factor to minimize damage to the oil-saturated core whenever we have a large permeability contrast in the favor of oil-saturated core. Injection of RPM polymer at low rate (1 cm3/min) was found to minimize damage to the oil-saturated core.
Field results showed that application of water control treatment using RPM polymer on an oil well resulted in a significant loss in oil production. Post treatment analysis indicated that RPM polymer solution entered mainly the oil-saturated zone, which was attributed to the large permeability contrast in favor of the oil-saturated zone. This paper will present detailed lab studies and field data obtained and will recommend the proper RPM polymer application method to avoid damaging oil producing zones.
Controlling Proppant Flowback to Maintain Fracture Conductivity and Minimize Workovers: Lessons Learned from 1,500 Fracturing Treatments
Authors: Trela Jim M. , Nguyen Philip D. , Smith Billy R. 
Published: February 2008

Abstract
The use of curable resin precoated proppants was often applied in the Permian Basin to control proppant flowback. However, these precoated proppant materials continued to allow proppant to produce back, especially during production surges because they did not provide sufficient consolidation strength to handle high drawdown. Since early 2005, a low-temperature curable liquid resin system has been selected to treat the proppant on-the-fly mainly during the tail-in stages in most of 1,500 hydraulic fracturing treatments. This paper highlights how the proppant back-production problems were successfully overcome through the application of this curable resin system. Detailed descriptions of the treatments, challenges, and lessons learned during the course of these fracturing treatments are presented.
Evaluation of these treatments has revealed that an optimum concentration of resin coating maximizes bonding between proppant grains and the consolidation strength of the coated proppant pack, locking the grains in place while minimizing any reduction of conductivity. Field results indicate that application of on-the-fly resin coating treatments effectively stops proppant flowback while allowing production rates to be maintained as designed. These treatments have drastically decreased the number of workovers for treated wells compared to those treated with resin precoated proppant or without resin treatments. This resin treatment process provides an economical means for controlling proppant flowback in wells with marginal reserves.
Understanding the Origin and Removal of Downhole Debris: Case Studies From the GOM
Authors: Javora Paul H. , Sanford Jack , Qu Qi , Robinson David , Poole Gary 
Published: February 2008

Abstract
Potential damage to the formation and generation of destructive wellbore debris can occur during perforating operations with shaped charges. One type of damage is to the formation, which is related in part to the powdered metals and metal alloys incorporated into the metal casings that contain the explosive charges in controlled debris perforating systems. Upon discharge, gun debris, including casing-metal residue and reaction products from the perforating system, can also contribute significantly to the overall amount of destructive wellbore debris generated. In addition, the debris often includes metal fragments from the wellbore casing, formation sand and other minerals, cement, and drilling fluid remnants that eventually are ejected into the wellbore. All of these materials can promote costly mechanical failures, contribute to well control problems, and hamper onsite operations.
Various factors influence the ultimate generation of destructive wellbore debris. These factors include gun type, fluid type, fluid density, bottom hole pressure and temperature, and the specific wellbore configuration and completion scenario employed. While previous authors have addressed formation damage issues or the impact resulting from the use of various casing metals, this work focused on the actual downhole debris generated and collected from the wellbore just after perforating the well, and relates these findings to the influencing factors. With the use of advanced downhole filtration and collecting techniques, downhole debris was collected from a series of deepwater projects in the GOM. Debris analysis coupled with well completion information has been studied. Results from the examination of downhole wellbore debris collected after perforating the well is presented and discussed.
Improved wellbore integrity and reduced risk are obtained through proper management of perforation and wellbore cleaning practices.
DMSP – Database for Modeling Signaling Pathways
Authors: Breit M. , Pfeifer B. , Baumgartner C. , Modre-Osprian R. , Tilg B. , Visvanathan M. 
Published: February 2008

Summary

Objectives:
Presently, the protein interaction information concerning different signaling pathways is available in a qualitative manner in different online protein interaction databases. The challenge here is to derive a quantitative way of modeling signaling pathways from qualitative way of modeling signaling pathways from a qualitative level. To address this issue we developed a database that includes mathematical modeling knowledge and biological knowledge about different signaling pathways.

Methods:
The database is part of an integrative environment that includes environments for pathway design, visualization, simulation and a knowledge base that combines biological and modeling information concerning pathways. The system is designed as a client-server architecture. It contains a pathway designing environment and a simulation environment as upper layers with a relational knowledge base as the underlying layer.

Results:
DMSP – Database for Modeling Signaling Pathways incorporates biological datasets from online databases like BIND, DIP, PIP, and SPiD. The modeling knowledge that has been incorporated is based on a literature study. Pathway models can be designed, visualized and simulated based on the knowledge stored in the DMSP. The user can download the whole dataset and build pathway models using the knowledge stored in our database. As an example, the TNF? pathway model was implemented and tested using this approach.

Conclusion:
DMSP is an initial step towards the aim of combining modeling and biological knowledge concerning signaling pathways. It helps in understanding pathways in a qualitative manner from a qualitative level. Simulation results enable the interpretation of a biological system from a quantitative and systemtheoretic point of view.
Modeling Repeated Time-to-event Health Conditions with Discontinuous Risk Intervals
Authors: Guo Z. , Gill T. M. , Allore H. G. 
Published: February 2008

Summary

Objectives:
Researchers have often used rather simple approaches to analyze repeated time-to-event health conditions that either examine time to the first event or treat multiple events as independent. More sophisticated models have been developed, although previous applications have focused largely on such outcomes having continuous risk intervals. Limitations of applying these models include their difficulty in implementation without careful attention to forming the data structures.

Methods:
We first review time-to-event models for repeated events that are extensions of the Cox model and frailty models. Next, we develop a way to efficiently set up the data structures with discontinuous risk intervals for such models, which are more appropriate for many applications than the continuous alternatives. Finally, we apply these models to a real dataset to investigate the effect of gender on functional disability in a cohort of older persons. For comparison, we demonstrate modeling time to the first event.

Results:
The GEE Poisson, the Cox counting process, and the frailty models provided similar parameter estimates of gender effect on functional disability, that is, women had increased risk of bathing disability and other disability (disability in walking, dressing, or transferring) as compared to men. These results, especially for other disabilities, were quite different from those provided by an analysis of the first-event outcomes. However, the effect of gender was no longer significant in the counting process model fully adjusted for covariates.

Conclusion:
Modeling time to only the first event may not be adequate. After properly setting up the data structures, repeated event models that account for the correlation between multiple events within subjects can be easily implemented with common statistical software packages.
Intravenous iron: From anathema to standard of care
Authors: Auerbach Michael , Coyne Dan , Ballard Harold 
Published: February 2008

AbstractA growing body of literature supports the use of intravenous iron as a compliment to erythropoiesis stimulatory therapy and in a significant number of disease states where iron is necessary and oral iron is ineffective or not tolerated. The differences in efficacy, safety, and clinical nature of serious adverse events that occur with the various iron preparations are poorly understood. Misinterpretation of adverse events leads to underutilization of this important treatment modality. Understanding the history of the development and use of intravenous iron is crucial to appreciate its importance in the management of anemias of dialysis, cancer, and cancer chemotherapy and properly assess side effects and toxicity. The benefits seen with intravenous iron therapy are independent of the pretreatment levels of serum ferritin, iron, total iron binding capacity, and percent transferrin saturation. Intravenous iron has been shown to overcome hepcidin induced iron restricted erythropoiesis in iron‐replete patients. Available clinical and experimental data suggest that increased utilization of intravenous iron should be considered. Am. J. Hematol., 2008. © 2008 Wiley‐Liss, Inc.
Longitudinal analysis of pulmonary function in adults with sickle cell disease
Authors: Field Joshua J. , Glassberg Jeffrey , Gilmore Annette , Howard Joanna , Patankar Sameer , Yan Yan , Davies Sally C. , DeBaun Michael R. , Strunk Robert C. 
Published: February 2008

AbstractAmong adults with sickle cell disease (SCD), pulmonary complications are a leading cause of death. Yet, the natural history of lung function in adults with SCD is not well established. We conducted a retrospective cohort study of adults with SCD who had repeated pulmonary function tests performed over 20 years of age. Ninety‐two adults were included in this cohort. Rate of decline in FEV1 for men and women with SCD was 49 cc/year (compared with 20–26 cc/year in the general population). Further studies are needed to identify factors which impact the rate of lung function decline in adults with SCD. Am. J. Hematol. 2008. © 2008 Wiley‐Liss, Inc.