Effects of shear fracture on in-depth profile modification of weak gels

2007 ◽  
Vol 4 (1) ◽  
pp. 55-60 ◽  
Author(s):  
Li Xianjie ◽  
Song Xinwang ◽  
Yue Xiang’an ◽  
Hou Jirui ◽  
Fang Lichun ◽  
...  
Keyword(s):  
Depth Profile ◽  
Shear Fracture ◽  
Profile Modification ◽  
Weak Gels

Mechanisms of Dopant Depth Profile Modification During Mass Spectrometric Analysis of Multilayer Structure

2015 ◽  
Vol 60 (6) ◽  
pp. 511-520 ◽  
Author(s):  
A.A. Efremov ◽  
◽  
V.G. Litovchenko ◽  
V.P. Melnik ◽  
O.S. Oberemok ◽  
...  
Keyword(s):  
Depth Profile ◽  
Multilayer Structure ◽  
Mass Spectrometric ◽  
Mass Spectrometric Analysis ◽  
Spectrometric Analysis ◽  
Profile Modification

scholarly journals Study on sweep efficiency improvement by in-depth profile modification

2013 ◽  
Vol 78 (6) ◽  
pp. 445-454 ◽  
Author(s):  
Sumihiko Murata ◽  
Akihisa Ashida ◽  
Satoru Takahashi ◽  
Hiroshi Okabe
Keyword(s):  
Depth Profile ◽  
Efficiency Improvement ◽  
Sweep Efficiency ◽  
Profile Modification

A Comparison of Polymer Flooding With In-Depth Profile Modification

2012 ◽  
Vol 51 (05) ◽  
pp. 393-402 ◽  
Author(s):  
Randall Seright ◽  
Guoyin Zhang ◽  
Olatokunbo Akanni ◽  
Dongmei Wang
Keyword(s):  
Depth Profile ◽  
Polymer Flooding ◽  
Profile Modification

Successful Field Pilot of In-Depth Colloidal Dispersion Gel (CDG) Technology in Daqing Oilfield

2006 ◽  
Vol 9 (06) ◽  
pp. 664-673 ◽  
Author(s):  
Harry L. Chang ◽  
Xingguang Sui ◽  
Long Xiao ◽  
Zhidong Guo ◽  
Yuming Yao ◽  
...  
Keyword(s):  
Oil Recovery ◽  
Colloidal Dispersion ◽  
Oil Field ◽  
Sweep Efficiency ◽  
Profile Modification ◽  
Production Wells ◽  
Daqing Oil Field ◽  
Incremental Oil Recovery ◽  
Water Cut ◽  
Weak Gels

Summary The first large-scale colloidal dispersion gel (CDG) pilot test was conducted in the largest oil field in China, Daqing oil field. The project was initiated in May 1999, and injection of chemical slugs was completed in May 2003. This paper provides detailed descriptions of the gel-system characterization, chemical-slug optimization, project execution, performance analysis, injection facility design, and economics. The improvements of permeability variation and sweep efficiency were demonstrated by lower water cut, higher oil rate, improved injection profiles, and the increase of the total dissolved solids (TDS) in production wells. The ultimate incremental oil recovery (defined as the amount of oil recovered above the projected waterflood recovery at 98% water cut) in the pilot area would be approximately 15% of the original oil in place (OOIP). The economic analysis showed that the chemical costs were approximately U.S. $2.72 per barrel of incremental oil recovered. Results are presented in 15 tables and 8 figures. Introduction Achieving mobility control by increasing the injection fluid viscosity and achieving profile modification by adjusting the permeability variation in depth are two main methods of improving the sweep efficiency in highly heterogeneous and moderate viscous-oil reservoirs. In recent years (Wang et al. 1995, 2000, 2002; Guo et al. 2000), the addition of high-molecular-weight (MW) water-soluble polymers to injection water to increase viscosity has been applied successfully in the field on commercial scales. Weak gels, such as CDGs, formed with low-concentration polymers and small amounts of crosslinkers such as the trivalent cations aluminum (Al3+) and chromium (Cr3+) also have been applied successfully for in-depth profile modification (Fielding et al. 1994; Smith 1995; Smith and Mack 1997). Typical behaviors of CDGs and testing methods are given in the literature (Smith 1989; Ranganathan et al. 1997; Rocha et al. 1989; Seright 1994). The giant Daqing oil field is located in the far northeast part of China. The majority of the reservoir belongs to a lacustrine sedimentary deposit with multiple intervals. The combination of heterogeneous sand layers [Dykstra-Parsons (1950) heterogeneity indices above 0.5], medium oil viscosities (9 to 11 cp), mild reservoir temperatures (~45°C), and low-salinity reservoir brines [5,000 to 7,000 parts per million (ppm)] makes it a good candidate for chemical enhanced-oil-recovery processes. Daqing has successfully implemented commercial-scale polymer flooding (PF) since the early 1990s (Chang et al. 2006). Because the PF process is designed primarily to improve the mobility ratio (Chang 1978), additional oil may be recovered by using weak gels to further improve the vertical sweep. Along with the successes of PF in the Daqing oil field, two undesirable results were also observed:high concentrations of polymer produced in production wells owing to the injection of large amounts of polymer (~1000 ppm and 50% pore volume) andthe fast decline in oil rates and increase in water cuts after polymer injection was terminated. In 1997, a joint laboratory study between the Daqing oil field and Tiorco Inc. was conducted to investigate the potential of using the CDG process, or the CDG process with PF, to further improve the recovery efficiency, lower the polymer production in producing wells, and prolong the flood life. The joint laboratory study was completed in 1998 with encouraging results (Smith et al. 2000). Additional laboratory studies to further characterize the CDG gellation process, optimize the formulation, and investigate the degradation mechanisms were conducted in the Daqing field laboratories before the pilot test. A simplistic model was used to optimize the slug designs and predict incremental oil recovery. Initial designs called for a 25% pore volume (Vp) CDG slug with 700 ppm polymer and the polymer-to-crosslinker ratio (P/X) of 20 in a single inverted five-spot patten. Predicted incremental recovery was approximately 9% of OOIP.

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