Field Experiment of Lignosulfonate Preflushing for Surfactant Adsorption Reduction
- S.A. Hong (Chevron Oil Field Research Co.) | J.H. Bae (Chevron Oil Field Research Co.)
- Document ID
- Society of Petroleum Engineers
- SPE Reservoir Engineering
- Publication Date
- November 1990
- Document Type
- Journal Paper
- 467 - 474
- 1990. Society of Petroleum Engineers
- 4.1.2 Separation and Treating, 5.6.5 Tracers, 4.3.4 Scale, 5.4.1 Waterflooding, 5.7.2 Recovery Factors, 5.3.4 Reduction of Residual Oil Saturation, 2.5.2 Fracturing Materials (Fluids, Proppant), 5.4.7 Chemical Flooding Methods (e.g., Polymer, Solvent, Nitrogen, Immiscible CO2, Surfactant, Vapex), 5.6.1 Open hole/cased hole log analysis, 5.3.2 Multiphase Flow, 5.2.1 Phase Behavior and PVT Measurements, 5.5.8 History Matching, 2.4.3 Sand/Solids Control, 4.1.5 Processing Equipment
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Lignosulfonate was field tested as a sacrificial adsorbate in conjunction with the ongoing Glenn Pool surfactant flood expansion project. A 2 wt% lignosulfonate solution was injected for 10 days as part of the preflush in this project. Results of the analyses of two observation well samples were interpreted for the effect of lignosulfonate on sulfonate adsorption and process performance. Even though the evidence was ambiguous, we concluded that the low-cost lignosulfonate preflushing was beneficial to surfactant flooding.
A laboratory study 1 found that surfactant loss could be reduced significantly by pretreatment of rock with a lignosulfonate preflush. The presence of lignosulfonate, however, caused more cations to be exchanged owing to the association of divalentions with lignosulfonate. An NaCl brine spacer was found to reduce the effect of increased divalent ions in the leading edge of the surfactant slug. It was also found that the brine tolerance and optimal salinity of petroleum sulfonate were not greatly affected by lignosulfonate. petroleum sulfonate were not greatly affected by lignosulfonate. Subsequently, lignosulfonate was field tested in conjunction with the Glenn Pool surfactant flood expansion project, in progress since 1982. The purpose of this field experiment was to confirm laboratory findings and to evaluate lignosulfonate as a sacrificial adsorbate in real-world situations. A lignosulfonate solution was injected as part of the preflush in one of the patterns without any interruption of the surfactant flood project. In accordance with our laboratory results, an NaCl brine spacer was injected after the lignosulfonate preflush and before the surfactant slug.
The Glenn Pool surfactant flood expansion project includes the Upper and Middle sands and 21 five-spot patterns on 92 acres [37.2 ha] in the William Berryhill lease of the Glenn Pool field. The project followed a 20-acre [8.1-ha] pilot test begun in 1979. The project followed a 20-acre [8.1-ha] pilot test begun in 1979. The field had been waterflooded since 1950 and had a residual oil saturation (ROS) of about 30%. The net pay thickness is about 95 ft [30 m] at a depth of 1,500 ft [457 m] - Porosity is about 20 %, and permeability averages about 150 md. The oil is a paraffinic crude permeability averages about 150 md. The oil is a paraffinic crude with a gravity of 37 degrees API [0.84 g/CM] and a viscosity of 4.4 cp [4.4 mPa-s] at a reservoir temperature of 95 degrees F [35 degrees C]. The surfactant flood process (Table 1) consisted of sequential injection of preflush, surfactant slug, tapered polymer slug, and drive water. preflush, surfactant slug, tapered polymer slug, and drive water. The lignosulfonate experiment involved two adjacent five-spot patterns (Fig. 1) in the northeastern part of the expansion area. The patterns (Fig. 1) in the northeastern part of the expansion area. The test pattern contained Injection Well 112 and Observation Well 141, while the control pattern contained Injection Well 106 and Observation Well 140. A lignosulfonate solution was injected into Well 112, and fluid samples were periodically taken from the two observation wells.
This paper summarizes and interprets data obtained from the observation well samples. Some simulation results with a chemical flood simulator are also included. This paper, however, does not cover the overall flood performance in the expansion project.
The general characteristics of the Glenn Pool field have been discussed elsewhere. The pilot performance showed that the Glenn sand has significant stratification and lateral variations. Figs. 2 and 3 show the porosities and oil saturations of the injection and observation wells in the test and control patterns. The test pattern exhibits numerous shale breaks and thin net sand, while the control pattern has fewer shale streaks. Figs. 2 and 3 also show that the pattern has fewer shale streaks. Figs. 2 and 3 also show that the initial oil saturation of Well 112 is somewhat higher than that of Well 106. Also, the resistivity log reveals that connote water in the test pattern is much saltier than that in the control pattern. These data suggest that the test pattern is more heterogeneous than the control pattern.
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