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Results
SUMMARY In this paper we present the modification and verification of a 3D frequency-domain electromagnetic modeling algorithm for dealing with heterogeneous, anisotropic magnetic permeability. To test the modifications, the code is verified against a 1D layered earth response, and 3D axially-symmetric doughnut model. In addition, to better understand the magnetic field responses to both conductivity and permeability, analytical analysis is performed and demonstrates that in a low induction number (|k * r|j « 1) regime the "magnetic current" or magnetization may be more important thant the induced electric current in determining the EM response to a medium.
Monitoring a Water Flood of Moderate Saturation Changes With Crosswell Electromagnetics (EM): A Case Study From Dom Joao Brazil
Wilt, Michael (Schlumberger) | Zhang, Ping (Schlumberger) | Maeki, Jorge (Schlumberger) | Netto, Paulo (Petrobras) | Queiroz, Jorge L.S. (Petrobras) | Santos, Jaciara B. (Petrobras) | Oliveira, Valterlene (Petrobras)
Summary Pattern water flooding has recently been pilot tested at the Dom Joao oil field in northern Brazil to improve recovery over the earlier peripheral flooding. The conformance and sweep of the injected water has been monitored over several years using well logs and crosswell EM and the small pilot features fiberglass cased injection wells which are also used for well based and crosswell monitoring using inductive measurements. Baseline crosswell EM data were collected in 2008, prior to initiation of water flooding in 2009. Time lapse crosswell EM and induction logging data collected in 2011 were used to image the water saturation changes between wells. After 2.5 years of flooding, repeated logs indicate that the resistivity has decreased from 12-15 ohm-m to 6-8 ohm-m in some intervals and less in others; this is less than half of the expected change and it is likely due to poor conformance. Tracking this small formation resistivity anomaly has proved challenging for the crosswell EM program, requiring high accuracy data collection and precision tool positioning to recover the 3%-5% field anomalies. Fortunately, benign field conditions and a newly developed field system have provided two remarkable data sets in which the data in non-flooded (i.e. shale) intervals repeat to 1% or less and the small anomalies recovered are imaged with some confidence. The crosswell results have provided an image consistent with the logs showing a low resistivity plume around each injector. The plume typically progresses 50-70m from each injector, and mainly in the upper parts of the reservoir. This suggests that the flooding is progressing slowly and that much of the injected water is traveling to producers in already swept intervals.
- South America > Brazil > Bahia > Reconcavo Basin > Dom Joao Field > Sergi-Água Grande Formation (0.99)
- South America > Brazil > Bahia > Reconcavo Basin > Dom Joao Field > Sergei Formation (0.99)
Scale Prediction and Inhibition for Oil and Gas Production at High Temperature/High Pressure
Fan, Chunfang (Rice University) | Kan, Amy T. (Rice University) | Zhang, Ping (Rice University) | Lu, Haiping (Rice University) | Work, Sarah (Rice University) | Yu, Jie (Rice University) | Tomson, Mason B. (Rice University)
Summary With the advance of new exploration and production technologies, oil and gas production has gone to deeper and tighter formations than ever before. These developments have also brought challenges in scale prediction and inhibition, such as the prevention of scale formation at high temperatures (150–200°C), pressures (1,000–1,500 bar), and total dissolved solids (TDS) (>300,000 mg/L) commonly experienced at these depths. This paper will discuss (1) the challenges of scale prediction at high temperatures, pressures, and TDS; (2) an efficient method to study the nucleation kinetics of scale formation and inhibition at these conditions; and (3) the kinetics of barite-crystal nucleation and precipitation in the presence of various scale inhibitors and the effectiveness of those inhibitors. In this study, nine scale inhibitors have been evaluated at 70–200°C to determine if they can successfully prevent barite precipitation. The results show that only a few inhibitors can effectively inhibit barite formation at 200°C. Although it is commonly believed that phosphonate scale inhibitors may not work for high-temperature inhibition applications, the results from this study suggest that barite-scale inhibition by phosphonate inhibitors was not impaired at 200C under strictly anoxic condition in NaCl brine. However, phosphonate inhibitors can precipitate with Ca at high temperatures and, hence, can reduce efficiency. In addition, the relationships of scale inhibition to types of inhibitors and temperature are explored in this study. This paper addresses the limits of the current predition of mineral solubility at high-temperature/high-pressure (HT/HP) conditions and sheds light on inhibitior selection for HT/HP application. The findings from this paper can be used as guidelines for applications in an HT/HP oilfield environment.
- North America > United States > California (0.46)
- North America > United States > Texas (0.28)
- Water & Waste Management > Water Management > Constituents > Salts/Sulphates/Scales (1.00)
- Energy > Oil & Gas > Upstream (1.00)
- North America > United States > Texas > Palo Duro Basin (0.99)
- North America > United States > Gulf of Mexico > Western GOM > West Gulf Coast Tertiary Basin > Keathley Canyon > Block 102 > Tiber Field (0.99)
Phase Stability and Inhibition of Calcium Sulfate in the System NaCl/Monoethylene Glycol/H2O
Lu, Haiping (Rice University) | Amy T, Kan (Rice University) | Zhang, Ping (Rice University) | Yu, Jie (Rice University) | Fan, Chunfang (Rice University) | Work, Sarah (Rice University) | Tomson, Mason B. (Rice University)
Summary Calcium sulfate is one of the major mineral scales in oil and gas production. Hemihydrate (CaSO4·0.5H2O) and anhydrite (CaSO4) are the predominant sulfate scales formed at high temperature, while gypsum (CaSO4·2H2O) scale may form at low temperatures (<~45°C). However, it has been shown in this study that anhydrite can form at low temperature in the presence of excess amounts of monoethylene glycol (MEG), and this may occur during offshore production with long tie-backs. The prediction and prevention of calcium sulfate scales requires knowledge of the phase behavior of the three major phases of calcium sulfate. The phase behavior of different calcium sulfate phases is related to the supersaturation state, temperature, and fugacity of water. In this study, the effect of a common hydrate inhibitor, MEG, on calcium sulfate solubility and phase behavior was investigated. This study was run with NaCl/CaSO4/MEG/H2O solutions at 0–6 molality (M) NaCl and 0–95 wt% MEG at 4–70°C. Three approaches were taken to determine the kinetics of calcium sulfate phase transition at various temperatures, ionic strengths, and MEG concentrations: (1) dissolution of gypsum, (2) dissolution of anhydrite, and (3) nucleation and precipitation of calcium sulfate by mixing calcium- and sulfate-containing solutions. The effect of scale inhibitors on phase transition was also evaluated. Phase transition of gypsum to anhydrite was observed in the presence of high concentrations of NaCl and MEG, regardless of the experimental approach. The transition boundary of temperature and concentrations of NaCl and MEG can be estimated from solubility of calcium sulfate and the fugacity of water. The inhibition mechanism of hexamethylene diamine tetra (methylene phosphonic acid) (HDTMP), one of the most effective inhibitors for calcium sulfate scale, was also tested by investigating the kinetics of precipitation and inhibition of calcium sulfate.
- Materials > Chemicals > Commodity Chemicals > Petrochemicals (1.00)
- Energy > Oil & Gas > Upstream (1.00)