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Abstract Calcium carbonate scale threats for deepwater developments have been predicted by calculating the saturation ratio (SR) and mass of calcium carbonate. Assessing the threat scale may pose to an operation allows the design and implementation of robust barriers to reduce the risk. Scale threat assessment is particularly important in the early phase of a project when options for controlling the threat are being evaluated. It is important to correctly interpretate scale prediction result and its operational significance in terms of the threat likelihood and severity. Widely adopted guidelines, based on industry experience built up over many years from operations in US land and in the North Sea, have been used to aid interpretation. However, the relevance of these guidelines for deepwater projects has long been challenged. The relationship between predicted SR and mass of calcium carbonate in deepwater is explored. Through case studies, it is apparent the current guidance is not stringent enough for deepwater. Additional guidance for deepwater operations is proposed. This paper describes the deepwater operational experience that was used to justify a change in the critical SR and mass values in the scale threat assessment guidelines now adopted to assess the likelihood of scaling in deepwater fields.
- Europe (1.00)
- North America > United States > Texas (0.47)
Engineered Nanoparticles for Hydrocarbon Dectection in Oil-Field Rocks
Berlin, Jacob M. (Rice University) | Yu, Jie (Rice University) | Lu, Wei (Rice University) | Walsh, Erin E. (Rice University) | Zhang, Lunliang (Rice University) | Zhang, Ping (Rice University) | Chen, Wei (Nankai University) | Kan, Amy T. (Rice University) | Wong, Michael S. (Rice University) | Tomson, Mason B. (Rice University) | Tour, James M. (Rice University)
Abstract Polyvinyl alcohol functionalized oxidized carbon black efficiently carries a hydrophobic compound through a variety of oil-field rock types and releases the compound when the rock contains hydrocarbons. The transport of small hydrophobic organic molecules through porous media has been studied for many years. In isolation, these hydrophobic molecules sorb very strongly to nearly all types of soil. However, it has been observed that these hydrophobic chemicals disperse more broadly in the environment than would be expected based on their strong affinity for binding to soil (Baker, 1986). One possible explanation for this behavior is that organic macromolecules, which possess amphiphilic characteristics, may sequester the hydrophobic small molecules and facilitate their transport by carrying them within the macromolecule (McCarthy, 1989; Enfield, 1988). Laboratory scale experiments have demonstrated this effect, with some cases, such as the use of β-cyclodextrin, showing highly efficient transport of a variety of hydrophobic aromatic molecules through soil (Brussea, 1994; Magee, 1991). However, selective release of the transported cargo has not been reported and β-cyclodextrin only forms 1:1 inclusion complexes with its hydrophobic cargo. Recently, a new class of compounds, nanomaterials, has been investigated for transport through porous media. Nanomaterials are defined as having at least one dimension of less than 100 nm, and they possess a much larger surface area relative to traditional polymers used for the transport of hydrophobic cargo. Nanomaterials are expected to have significantly different transport behavior in porous media as a result of their larger size and more rigid shape as compared to polymers, and the design of nanoparticles (NPs) with efficient subsurface transport is an ongoing challenge. Nanomaterials prepared from a variety of precursors, including carbon, iron and silica, have varying abilities to flow through porous media. Water-dispersible aggregates of [C]fullerenes can flow through sand samples and glass beads, although the breakthrough of the fullerenes is very low at early pore volumes and gradually increases over time (Wang, Y., 2008; Li, 2008). The use of a water-soluble fullerene derivative, as opposed to the water-dispersible aggregates, showed improved breakthrough for a column of glass beads (Lecoanet, 2004). Single-walled carbon nanotubes (SWCNTs), which are also prone to aggregation, show limited breakthrough in porous media (Jaisi, 2009). Reducing the SWCNTs ability to aggregate by wrapping them with a surfactant or binding humic acid to them improves their mobility in porous media (Wang, P., 2008). Similar behavior has been observed for silica and iron, as functionalization of the particles with a hydrophilic polymer, either polyethylene glycol (PEG) or carboxymethyl cellulose, reduces their affinity for aggregation and improves their transport through porous media (Lenhart, 2002; Rodriguez, 2009; He, 2009; Saleh, 2007).
- Materials > Chemicals > Commodity Chemicals > Petrochemicals (1.00)
- Energy > Oil & Gas > Upstream (1.00)
- North America > United States > West Virginia > Appalachian Basin > Berea Sandstone Formation (0.89)
- North America > United States > Pennsylvania > Appalachian Basin > Berea Sandstone Formation (0.89)
- North America > United States > Ohio > Appalachian Basin > Berea Sandstone Formation (0.89)
- (2 more...)
Ultra-HTHP Scale Control for Deepwater Oil and Gas Production
Fan, Chunfang (Rice University) | Shi, Wei (Rice University) | Zhang, Ping (Rice University) | Lu, Haiping (Rice University) | Zhang, Nan (Rice University) | Work, Sarah (Rice University) | Al-Saiari, Hamad A. (Rice University) | Kan, Amy T. (Rice University) | Tomson, Mason B. (Rice University)
Abstract Scale control in deepwater oil and gas production is often challenging due to not only the geological and mechanical limitation associated with deepwater wells, but also the high temperature (>150°C) and high pressure (>10,000 psi) environment, which may be associated with brine containing high total dissolved solids (TDSs > 300,000 mg/L or greater). These extreme conditions make scale prediction, control and testing difficult because of the requirements for special alloy, pumps and control equipments that are not readily available. Therefore, very few reliable ultra-HTHP data are available. To overcome such challenges, an efficient flow-loop method has been established to study both the equilibrium and kinetics of scale formation and inhibition at ultra-HTHP conditions. This paper will discuss (1) an efficient flow-loop method to study the solubility of scale minerals at ultra-HTHP conditions; (2) solubility of barite at a temperature up to 200°C and pressure up to 20,000 psi; and (3) scale control and inhibitor selection for deepwater oil and gas production at ultra-HTHP conditions. Specifically, the performance and thermal stability of some common scale inhibitors at the high temperature conditions were studied in terms of barite inhibition. The results to-date indicated that (1) the solubility of barite at up to 200°C and 24,000 psi can be precisely measured by this newly developed flow-loop apparatus; (2) the rate of mineral scale formation at HTHP may be considerably faster than previously projected from low temperature studies and hence, difficult to inhibit; (3) different scale inhibitors have shown considerably different thermal stability. The results and findings from these studies validate a new HTHP apparatus for scale and inhibitor testings and information for better scale control at HTHP condition.
- North America > United States (0.68)
- Europe (0.46)
- Energy > Oil & Gas > Upstream (1.00)
- Water & Waste Management > Water Management > Constituents > Salts/Sulphates/Scales (0.56)
- Reservoir Description and Dynamics > Unconventional and Complex Reservoirs > HP/HT reservoirs (1.00)
- Production and Well Operations > Production Chemistry, Metallurgy and Biology > Inhibition and remediation of hydrates, scale, paraffin / wax and asphaltene (1.00)
- Facilities Design, Construction and Operation > Flow Assurance > Solids (scale, sand, etc.) (1.00)
Abstract As water cuts increase world wide it becomes more important to control the adverse effects of injected and produced waters. The challenges are greater due to the wider ranges of T, P, and compositions of injection and production fluids. Both equilibrium and rate processes are important to scale and corrosion control. The Brine Chemistry Consortium (BCC) at Rice University has expanded the range of its software to include prediction of brine pH, scale supersaturation for common oilfield scales, mass transport, and the effect of various concentrations of scale inhibitors in the presence and absence of hydrate inhibitors, over a temperature range of about 32 to 400 ºF (0 to ˜200 ºC), or greater, and pressures from atmospheric to between one and two thousand atmospheres. Many of these models are based upon data developed at the BCC. Comparatively, only limited work has been done to model the kinetics under conditions important to production. Models have been developed and tested experimentally to include the effects of both methanol (MeOH) and mono-ethylene glycol (MEG) on pH, scale formation, and inhibitor kinetics from zero to 100% MeOH or MEG over the range of conditions commonly found. It has been found experimentally and justified theoretically that once the effect of MeOH or MEG on supersaturation has been modeled, the impact on minimum inhibitor concentration (MIC) and nucleation kinetics for common scales is readily predicted. Even less work has been done to characterize the effects of cosolvents on kinetics. In order to model small changes in composition, as can be important with iron/zinc, etc., carbonates and sulfide formations, a new high efficiency algorithm that incorporates several numerical methods simultaneously has been developed to assure calculation fidelity even in extreme ranges of composition. Limiting equations will be developed that incorporate some kinetics into brine chemistry modeling for flow in porous media and for flow in pipes.
- Materials > Chemicals > Commodity Chemicals > Petrochemicals (1.00)
- Energy > Oil & Gas > Upstream (1.00)
Abstract A surfactant-assisted synthesis route was developed to form nanometer sized metal-phosphonate particles to expand its use in the delivery of phosphonate inhibitors into porous media for scale control. Aqueous solutions of calcium chloride and zinc chloride were mixed with basic solution containing phosphonate scale inhibitors, such as diethylenetriamine-penta (methylene phosphonic acid) (DTPMP) or BHPMP in the presence of sodium dodecyl sulfate (SDS) and/or tetradodecylammonium bromide (TTAB) surfactants. The physical and chemical properties of the fabricated nanoparticles have been carefully evaluated. A large number of fabrication procedures are screened and only those that yield the metal-phosphonate particles in the diameter of 50–200 nm with various shapes are further evaluated. Furthermore, these nanoparticles should meet the criteria of forming stable suspension over 12 hours at 70 °C and up to 2% KCl. The nanoparticles are capable of traveling through the porous media and depositing into the formation during a shut-in period. After that, production is resumed and the inhibitor nanoparticles are dissolved into the produced fluid to prevent scale formation. The potential application of synthesized nanoparticles in inhibitor treatment in oil fields was tested by laboratory squeeze simulations, where the nanoparticles can be placed at distance away from the injection port and retained by the porous media and returned slowly as flow back with synthetic brine. The retention and long term flow back performance of metal-phosphonate particles will be reported. Introduction: In many oil fields, as gas and oil production progresses, the ratio of produced brine water to hydrocarbons often increases. Typically, 10 to 20 barrels of brine will be produced with one barrel of oil or gas equivalent. These brines are corrosive and tend to produce calcite or sulfate scales [1]. Along with other forms of scales, calcite (calcium carbonate) is the most common type of scale deposits formed in the oil industry. According to Tomson et al [2], precipitation of calcite in hydrocarbon production activities is primarily attributed to the solubility drop due to pressure decrease and the raising pH due to the changing of partial pressure of carbon dioxide. Usually, scales form in the formation near the perforation or in the production tubing as well as in the surface of facilities. Phosphonate is widely used in industry for scale and corrosion control [3] and is referred as the threshold scale inhibitor because it can prevent scale nucleation and formation at concentration of several milligrams per liter of brine water. Generally, 0.1 mg/L to 1 mg/L of phosphonate inhibitors can be sufficient to prevent scale formation. Even though much research has been performed, the mechanism of inhibitor functioning to inhibit scale formation is still under debate [4]. Delivery of phosphonate inhibitors to production well is commonly applied through an inhibitor squeeze treatment, where inhibitors are squeezed into downhole formation so that they can precipitate with divalent cations, mostly calcium, and slowly release into production brine fluid to prevent scale formation [4–6]. Although the squeeze treatment has been proven to be very successful in terms of long protection time, especially in carbonate reservoirs [7], there are several shortages of applying this method in the oilfield. One of the drawbacks is that only small portion of inhibitors can be retained by the formation and a large fraction is eluted out of the reservoir upon initial injection, making it not economical for field application [2]. The other disadvantage of the conventional squeeze treatment is that the acid in the acidic pill solution will dissolve and mobilize calcium from the formation, leading to Ca-phosphonate precipitation near the wellborn. As a result, only limited distance can be protected due to this quickly occurring reaction of calcium and phosphonate [8]. It is desirable that most of inhibitors are retained by the formation materials and returned at concentrations close to the minimum concentration required to inhibit scale formation for a long time in resumed production processes. Therefore, understanding of the mechanism and chemistry of divalent cation-phosphonate is of great importance for enhancing the performance of inhibitors in the squeeze treatment.
- North America > United States (1.00)
- Europe > Norway > Norwegian Sea (0.24)