bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Novel Method of Preventing Perforation Damage In High-Temperature Offshore Wells
Authors: McElfresh Paul , Gabrysch Allen , Van Sickle Ed , Myers Bill , Huang Tianping 
Published: December 2007

Abstract
During the course of normal perforating operations, special attention is paid to minimizing debris in order to prevent perforation tunnel plugging or other forms of formation damage. However, operational constraints, especially in high-temperature offshore wells, may result in freshly perforated zones being left in contact with brines or formation fluid for a long time. Exposure to these fluids can cause zinc-containing scales to form inside perforation tunnels or zinc particles to become embedded in the formation, which in turn may cause damage to the full-flow potential of the perforations. Since the damage potential increases with brine density and pressure, the risk is greater in high-temperature/high pressure wells.
The damages described above can be prevented or eliminated by using a perforating acid. However, at high temperatures acid corrosion rates must be taken into account when selecting an effective acid system. Debris can be removed with strong acid or prevented with an inhibitor, but as formation temperatures increase, metal corrosion and acid sensitivity of the formation become highly problematic. At these higher temperatures, organic acids are often used, but many of them do not have the acid strength or the capability to dissolve zinc or zinc salts.
This paper describes a highly biodegradable organic acid system that has high zinc dissolution activity but low corrosion rates to steels and chrome alloys. The corrosivity of these acids is low enough that it can be spotted above the perforation guns for long periods of time at high temperature to aid in the immediate prevention and/or clean-up of formation damage products. Corrosion tests have shown that at 350°F, the corrosion rate caused by the biodegradable organic acid is 0.001 lbs/ft2 on 22-Cr for 16 hours, a value that is 90% lower than that of acetic acid under the same conditions. Acid reaction tests have confirmed that this new acid system can effectively prevent formation damage induced by perforation at temperatures up to 400°F. These tests and their effects on well production will be described in detail in the paper.
Formation Damage Due to Scale Formation in Porous Media Resulting From Water Injection
Authors: Moghadasi J. , Jamialahmadi M. , Müller-Steinhagen H. , Sharif A. 
Published: December 2007

AbstractDue to the extensive use of water injection for oil displacement and pressure maintenance in oilfields, many reservoirs experience the problem of scale deposition when injection water starts to break through. In most cases the scaled-up wells are caused by the formation of sulfate and carbonate scales of calcium and strontium. Due to their relative hardness and low solubility, there are limited processes available for their removal and preventive measures such as the ‘squeeze’ inhibitor treatment have to be taken. It is therefore important to gain a proper understanding of the kinetics of scale formation and its detrimental effects on formation damage under both inhibited and uninhibited conditions.This paper presents the results of an experimental and theoretical study of permeability reduction of porous media caused by scaling. Two incompatible solutions of calcium and /carbonate ions were injected into the porous medium, where calcium or calcium carbonate was generated by chemical reaction. Mechanisms by which a precipitate reduces permeability include solids deposition on the pore walls due to attractive forces between the particles and the surfaces of the pores, individual particles blocking pore throats, and several particles bridging across a pore throat. The characteristics of the precipitate influence the extent of formation damage. Conditions such as large degree of supersaturation, presence of impurities, change in temperature, and rate of mixing controls the quantity and morphology of the precipitating crystals.
Modeling Pressure and Temperature Effects on Reactive Flow and its Impact on Well Performance under Common Operational Conditions
Authors: Araque-Martinez Aura , Lake Larry W. 
Published: December 2007

Abstract
Reactive flow in a permeable medium is a combination of reactions between the fluids and minerals in the host formation and reactions within the same fluid. Among these reactions, solid dissolution and precipitation are important reactions since precipitated reactions products, in particular, can plug flow channels and cause flow impairment. The subject of this work is the simulation of these aqueous phase reactions during flow.
Simulation of these geochemical reactions is based on solubility calculations, which depend on pressure and temperature among other parameters. Pressure dependency becomes important where large pressure changes occur as in near wellbore flow. Similarly, injecting a fluid that is at a different temperature from the reservoir (as in hot water injection) can cause geochemical reactions even if the injected fluid and resident fluid have the same composition. Modeling these geochemical reactions can get even more complicated during production after hot water injection (push-pull cycles) since the inlet fluid composition may change in each cycle. Neglecting these effects can lead to an unrealistic estimate of the predicted precipitates, since solubility depends on pressure and temperature.
This work presents a simplified approach, based on experimental literature data as well as thermodynamic properties to account for solubility changes as a function of pressure and temperature in geochemical modeling. Reactive flow is based on nonequilibrium aqueous-solid reactions. The approach is novel because it allows for the effects of pressure and temperature changes on solubility calculations during the production and injection period as well as the change in the inlet fluid composition for push-pull cycles.
We illustrate the model results on two cases, one production and the other an injection-production combination: We model flow from a producer in West Texas carbonate reservoir in which there may be substantial well impairment due to gypsum precipitation. Pressure changes have more effect on mineral precipitation in producer than injectors, since most of the sulfates tend to become less soluble as pressure decreases, however, water must flow to cause significant precipitation.We also study the effect on the productivity of a well after hot water has been injected and the well returned to production. We use data from a sandstone reservoir that initially contained kaolinite. K-feldspar and quartz are possible secondary minerals. Results show that during the production cycle kaolinite re-precipitation is likely to occur; quartz and K-feldspar precipitate during the injection cycle.
The damage during production is more severe that during injection.
Alternate Path Completions: A Critical Review and Lessons Learned From Case Histories with Recommended Practices for Deepwater Applications
Authors: Hurst G. , Cooper S. D. , Norman W.D , Dickerson R. C. , Claiborne E. B. , Parlar M. , Tocalino S. 
Published: December 2007

Abstract
Since its introduction, over 700 alternate path sand control completions have been implemented around the world ranging from single zone cased hole gravel-packs to multi-zone fracpacks and fibre optic (DTS) enabled open hole horizontal completions. Over the last six years, the alternate path system has been field proven to provide high reliability in achieving complete packs as well as additional features allowing simultaneous cake cleanup, shale bypass and other contingencies that enable doing it right the first time in deep-water/subsea completions where interventions tend to be economically and logistically prohibitive.
This paper provides a critical review of those completions, capturing both successes and failures, along with the lessons learned in their design, execution and evaluation in relation to completion efficiency in sanding reservoirs. Furthermore, it details future development work and enablers that will allow the use of alternate path technology as the mainstay of intelligent well solutions, geometrical design improvements to provide optimal aspect ratios in the wellbore and its applicability in conjunction with water packing.
Changes in Perforation-Induced Formation Damage with Degree of Underbalance: Comparison of Sandstone and Limestone Formations
Authors: Halleck Phillip M. , Karacan C. Ozgen , Hardesty John , Detwiler Russ 
Published: December 2007

Abstract
Field data and recently developed models provide some guidance for estimating the underbalance needed to obtain fully functional perforations, but there are little data available that relate flow efficiency to lower underbalances in different rock types. To improve understanding of the surge cleanup process, we have performed two series of perforation flow tests in Berea Sandstone and in Bedford Limestone cores at increasing levels of underbalance. Flow tests were performed according to modified API RP19B, section 4 test procedures. At the conclusion of the tests, the cores were analyzed using high-resolution X-ray CT techniques. The shape, dimensions and total volumes of both the open tunnel and the remaining embedded liner metal were extracted from the CT data and correlated with the underbalance and with the flow test results.
Open tunnel diameters and volumes are much lower in the limestone samples, and there is preliminary evidence of a compacted zone surrounding the tunnel that is not present in the Berea samples. While the amount of metal remaining in the tunnel and at the perforation tip decreases dramatically with underbalance in Berea Sandstone cores, the amount of metal is nearly constant in the limestone cores. Conversely, the tunnel volume increases with underbalance in the Sandstone cores but stays constant in the limestone. Preliminary core flow efficiency (CFE) results correlate well with these observations. There is a shape increase in CFE in the sandstone samples as the tunnel volumes increase and little change in CFE in the limestone samples corresponding to unchanging tunnel volume.
The tests also offer some evidence of the cleanup mechanism at the perforation tip, at least in the sandstone cores. Samples at intermediate underbalance levels show evidence of open tunnel space in an annulus surrounding the metal slug at the tip. This suggests that cleanup may proceed, at least partially, by axial flow through crushed rock surrounding the metal. As this material erodes away, the metal is loosened and is flushed from the tunnel. Existing models for cleanup are based primarily on radial flow.
Underbalance Pressure Criteria For Perforating Carbonates
Authors: Subiaur Servio T. , Graham Craig A. , Walton Ian C. , Atwood David C. 
Published: December 2007

Abstract
Underbalance perforating has long been recognized as one of the best techniques for mitigating perforating damage. Earlier studies have attempted to establish the level of underbalance necessary to stimulate perforation clean-up in sandstone. These models are stated in terms of the underbalance pressure thought necessary to remove damage from perforations for a given matrix permeability (some models also give consideration to fluid properties and perforation geometry). The purpose of this study is to evaluate the extent to which these correlations for underbalance perforating may be applicable to carbonates.
Single shot laboratory flow tests were performed with limestone and dolomite cores to determine the extent of perforation damage as a function of underbalance pressure. The calculated perforation skins from the carbonate perforating experiments are not well described by the earlier sandstone correlations. In particular, the primary reliance on rock permeability as a prognosticator of perforation clean-up does not work for carbonates. Rather than relying upon the initial underbalance pressure and matrix permeability as has been done previously for sandstones, perforation skin for carbonates is best related to peak underbalance pressure and rock strength. The underbalance pressure condition is not surprising. Progressive perforation clean-up with increasing underbalance is intuitive and has been well noted by previous investigators. This study extends the concept by making reference to a peak dynamic underbalance pressure occurring during perforating. Relating rock strength instead of rock permeability to perforation clean-up is a relatively new idea that may also have merit for sandstones. The results of this study suggest that the initial mechnism of perforation clean-up is primarily related to failure of the perforation tunnel wall under stress as opposed to fluid surge flow.
Annular Barrier Re-Establishment Using a Long-Life, High-Strength Polymer Gel System
Authors: Mebratu Amare , Nerland Børge , Kleppan Tore 
Published: December 2007

Abstract
Well A-01A in the Valhall field has been on production since late 1993, but its performance has been unstable with proppant and chalk flowback. Mechanical impairments have been repaired, the subsurface safety valve (SSSV) was locked open, and an insert SSSV was installed in May 2001. Although the control line was repeatedly treated with a pressure-activated sealant, leakage has been a recurring problem.
Recently, a production tubing annulus communication was detected in Well A-01A. The leak point was believed to be at the seal assembly at the bottom of the production tubing string. The operator and service company engineers evaluated the mechanism of the leak and its severity.
In January 2003, 30 bbl of a long-life, high-strength polymer system (HSPS) were placed in the annular space between the 5 ½-in. production tubing and 9 5/8-in. casing. Applying this polymer system as an annular barrier was a new technique. A temporary gel plug (TGP) consisting of a hydroxy propyl guar polymer and a crosslinker was pumped both ahead and behind the HSPS for placement accuracy and to prevent contamination. Because the well was at low pressure, base oil was used as a displacement fluid. The base oil helped reduce hydrostatic head under placement. The well was kept producing at normal rates during the operation, and pumping was completed within 4 hr with no production loss and no downtime.
Annulus pressure was dramatically reduced from 1,300 psi to less than 250 psi. Some pressure increase was observed following well intervention work, but later pressure stabilized at 600 to 700 psi. When the well was shut in, there was no pressure increase observed in the annulus, while the tubing pressure increased from approximately 800 to 2,000 psi. Currently, the well is producing oil at 2,200 BOPD. Stable annulus pressure and normal production performance indicate that the annular gel plug is effectively blocking the communication. The use of this long-life polymer gel plug as an annular barrier is intended to keep the well producing until a tubing workover is possible and a permanent barrier is established. Payback time for the total cost of this operation is approximately four days.
This paper describes the polymer gel systems, placement technique, operational aspects, and benefits of the method used.
A New Field Method for Determining the Levels of Iron Contamination in Oilfield Completion Brine
Authors: Carpenter Joel F. , Dalton Ferrill G. , Isaac D. Donald , Freeman Michael A. , Prasek Bethicia B. , Guy-Caffey Judith K. , Tomlin Marsha , Javora Paul , Berry Sandra L. , Jones Tom A. , Malachosky Ed , Neale Teresa 
Published: December 2007

Abstract
Quantifying total iron in brine is critical in order to mitigate its unfavorable effects. An API-sponsored work group has developed a robust field method for determining the levels of iron contamination in all oilfield completion brine, including zinc-based brine. This colorimetric, semi-quantitative method is based on chemistry involving acidification, peroxide oxidation, and thiocyanate complex formation. The iron content is quantified by comparing the intensity of the resulting colored complexes to standards.
Using newly-developed, commercially available vacu-ampoule test kits (Figure 1), this assay is quick and particularly user-friendly, and it is easily implemented in the field. It is anticipated that this method will be incorporated into the API Recommended Practice 13J, Testing of Heavy Brine.
Microemulsion Additives Enable Optimized Formation Damage Repair and Prevention
Authors: Pursley John T. , Penny Glenn , Holcomb David 
Published: December 2007

Abstract
A new microemulsion additive has been developed that is effective in remediating damaged wells and is highly effective in fluid recovery and relative permeability enhancement when applied in stimulation treatments at dilute concentrations.
The microemulsion is a unique blend of biodegradable solvent, surfactant, co-solvent and water. The nanometer sized structures are modeled after Veronoi structures which when dispersed in the base treating fluid of water or oil permit a greater ease of entry into a damaged area of the reservoir or fracture system. The structures maximize surface energy interaction by expanding to twelve times their individual surface areas to allow maximum contact efficiency at low concentrations (.1-.5%). Higher loadings on the order of 2% can be applied in the removal of water blocks and polymer damage.
Lab data is shown for the microemulsion in speeding the cleanup of injected fluids in tight gas cores. Further tests show that the microemulsion additive results in lower pressures to displace frac fluids from propped fractures resulting in lower damage and higher production rates. This reduced pressure is also evident in pumping operations where friction is lowered by 10-15% when the microemulsion is added to gelled fracturing fluids.
Field examples showing remediation and stimulation are provided from the Rocky Mountains, and the Ft Worth basin.
One Step Beyond: Managing Areas of High Biodiversity Value
Authors: Macklin Stephen , Kapila Sachin , Hartog Jan 
Published: December 2007

Abstract
The scientific consensus is that biodiversity is under increasing threat from habitat loss, climate change and pollution. The challenge to protect areas of high biodiversity value is gaining profile and the issue is not going to go away. Increasingly, society is expecting the oil/gas industry to make a broader contribution to solving the issue and increasingly industry wants to make that contribution. Hydrocarbon resources required to meet future demand for affordable energy are often located in protected or sensitive areas, which can give rise to tensions around competing land use.
At the heart of the issue is the call to establish a universal system of protected areas. Protected areas was a key theme at the World Parks Congress in September 2003 and will also feature in the 7th Conference of the Parties to the UN Convention on Biological Diversity (CBD) in February 2004.
Government signatories to the CBD are required to establish areas to protect biodiversity as part of their obligations under international law. There are a number of global systems for designating protected areas. World Heritage Sites are designed to protect areas of outstanding universal value and are also part of government's international obligations. Oil and gas activities are not considered compatible with the objectives of such sites. The UN List of National Parks and Protected Areas is classified into six categories by the World Conservation Union (IUCN). The Category System was not designed to define where industry should and should not operate, but is increasingly being used to determine land use options, although this system lacks the clear rules and procedures that characterise the World Heritage Convention. Then there are other protected areas systems such as Ramsar (for wetlands) or man and biosphere reserves. Governments may also put in place regional or national regulatory frameworks such as the European Union Habitats and Birds Directives (Natura 200 sites). Less formal are areas or regions that have been prioritised by various conservation organisations - these differ according to the criteria used by the organisation.
There is a lack of trust between the conservation community and business. Some NGOs are willing to engage, but are coming under pressure to deliver benefits to conservation. Others are more adversarial. Financial institutions are also enquiring about company policy with respect to operating in protected areas.
All these factors will affect us. We therefore need to position ourselves to manage this issue in the long term. The paper will outline the case for action, the recent developments within and key challenges faced by the Shell Group - particularly Shell EP, and the key features of its approach.
Management of Oil & Gas Exploration and Production in Sensitive Social Environment and Mangrove Ecosystem
Authors: Suripno S. , Najib M. , Asmaradewi Gayatri 
Published: December 2007

Abstract
TOTAL E&P INDONESIE (TI), a subsidiary of TOTAL Group, has been operating in Mahakam Contract Area for more than 30 years, despite of increasing sensitivity in the operation area from social environment and mangrove ecosystem point of view. Handil and Tunu Field are located in Mahakam Delta area, which was initially covered by dense mangrove vegetation. In the last decade there has been very rapid increase of local population activities and deforestation due to shrimp-culture development. Hence, Company faced more challenges in managing environment of E&P activities in such sensitive social environment and mangrove ecosystem.
TI carried out some big efforts of environmental management actions to protect mangrove ecosystem through several programs such as minimizing land clearing and reinstatement of cleared area. These environmental programs involved local communities and other stakeholders such as NGOs and governmental bodies. Other actions to manage mangrove ecosystem were also carried out through a sustainable development steering committee. The committee launched programs related with institutional aspects, regulatory framework, law enforcement, community awareness improvement, etc.
The growth of local economic activities attracted more people to come to the delta area. Increasing number of people gave impacts to E&P activities especially through environmental issues. Number of claims and disturbances from local people increased. Therefore, the Company initiated some approaches to manage such issues, such as participatory community development, environmental claim management, and social approaches through environmental programs.
All those actions were wrapped in the frame of sustainable development programs where environment is part of it.
The above efforts resulted in successful solutions for social environmental problems and generated good track record in protecting mangrove ecosystem. Process of implementation on site was challenging and very interesting to be shared among other companies operating in sensitive area.
ESIA Experiences and Lessons in China
Authors: Luo Huaisheng 
Published: December 2007

Abstract
Since China re-opened its doors to multi-nationals in the 1980s, Shell has developed its oil and gas activities in the country. In the past 10 years, Shell has conducted near twenty environmental and social impact assessments (ESIAs) in China, ranging from offshore&onshore seismic survey, exploration drilling, gas field development, pipeline, coal gasification plant, to petrochemical complex. The implementation of EIA Law in September 2003 is a milestone in strengthening the environmental impact assessment process for development projects in China.
The learnings from these ESIAs are shared, notably in respect of the practicalities of conducting them to international expectations, and the importance of JV partners supports/buy-in to their successful implementation.