Alkaline/Surfactant/Polymer Pilot Performance of the West Central Saertu, Daqing Oil Field

Abstract

Summary A tertiary pilot application of the Alkaline-Surfactant-Polymer (ASP) process was initiated in September, 1994 in West Center Area of Daqing Oil Field. The pilot pattern consists of 4 inverted five-spot, including 4 injectors and 9 producers, as well as 2 observation wells encompassing an area of 90,000 m2 and with a pore volume of 203,300 m3. The target layer is Saertu II1-3 sandstone with average porosity of 26% and permeability of 1.426 m2. The crude oil viscosity is 11.5 mPa.S at reservoir temperature and the connate water salinity is 6,800 mg/L. The current pilot performance shows a pronounced response from Alkaline-Surfactant-Polymer injection. The average pilot area oil production rate increased from 36.7 m3/d to 91.5 m3/d, while water cut decreased from 82.7% to 59.7%. For the central well Po5, which is surrounded by injection wells, the oil production rate increased from 3.7 m3/d to 27.1 m3/d while water cut decreased from 87.9% to 45.8%. The numerical simulation results forecast that the oil recovery will be increased by 18.1% OOIP. Introduction The Daqing oil field is the largest field in the Peoples Republic of China. The pilot site is located on the west limb of the Saertu anticline. The reservoir slopes gently from east to west with an average depth of 814 m. The target layer in the pilot area, the Saertu II1-3 sandstone formation was deposited in a flood plain distributary environment. The sandbody is mainly composed of highly meandering distributary sandstone. The sandstone reservoir distribution is wide and thick, with high permeability and high inter-formational heterogeneity. The connate water salinity is relatively low, and fresh water is available. The reservoir characteristics, fluid properties, waterflood performance, and the performance of polymer flood pilot tests, indicated that the Daqing field was an ideal candidate for the Alkaline-Surfactant-Polymer process. Other papers have reported on ASP performance of field projects in the United States, but this paper reports on ASP effect at an advanced stage of waterflooding in the Daqing ASP pilot. History The Daqing field was discovered in 1959. Generalized water injection began in June of 1960 and separate layer injection began in January of 1965. The field was developed in a line drive pattern with rows of injectors 2,400 meters apart and spacing between wells within a row of 500 meters. Between rows of injectors are 3 rows of producing wells evenly spaced at 600 meters between rows. The oil production has been maintained at more than 160,000 m3/d since 1979 by this infill drilling and development resulting in more than 10,000 wells. Artificial lift development began in January of 1981 continuing until December of 1989. Beginning in 1984 the reservoir characteristics were screened for the application of enhanced oil recovery techniques. Two polymer flood pilots were performed beginning in 1987 with watercuts decreasing an average of 16% and oil rates increasing three-fold. These results indicated that mobility control polymer flooding could significantly improve oil recovery. As a result of these pilots, on-site polymer manufacturing facilities were built capable of producing 50,000 tons of polyacrylamide polymer per year. This facility began initial production in September of 1995. The Alkaline-Surfactant-Polymer process was identified as a means to further increase recovery and utilize the polymer made on site. The pilot area was originally developed beginning in December of 1987 for one of the polymer flood pilots. However, the polymer flood produced from intervals about 100 m deeper than the Alkaline-Surfactant-Polymer pilot. Fig. 1 shows the pilot area located between the well Zhong 5-8 and - Zhong 5-10 in the west central area of Daqing Field.

Impact of Alkaline-Surfactant-Polymer Flooding Model on Upscaled Recovery Predictions: Medium and Heavy Oils

“…The results of corefloods, pilot tests (Hawkins et al 1994;Deng et al 2002;Hou et al 2006;Liu et al 2004;Nedjhioui et al 2005;Ibrahim et al 2006;Shutang et al 1996) and field-wide floods, mostly in USA and China (Meyers et al 1992;Falls et al 1994;Pitts et al 1994), show the potential of the ASP process to improve oil recovery. In general, its recovery efficiency is higher than that of alkaline-polymer (AP) or just straight polymer (P) flooding (Taylor et al 1996;Shuler et al 1989), although it may not always be applicable to all reservoir conditions.…”

Oil Recovery From Fractured Carbonates by Surfactant-Aided Gravity Drainage: Laboratory Experiments and Mechanistic Simulations

“…Numerical simulators (John et al 2005, Shutang et al 1996 have been developed in the past for chemical flooding in which the IFT changes along the reservoir with time. John et al (2005) incorporate oil/surfactant/brine-phase behavior using Hand's rule and trapping number model for relative permeability in their simulator.…”

Performance and Effect Analysis of ASP Commercial Flooding in Central Xing 2 Area of Daqing Oil Field

“…Figure 4 The simulation curves of the east part of ASP flooding core wells in Xing2 center (2)Due to the impact of multi-layers and multi-well group, the decrement of water cut in the commercial test area is less than that in the small scale test area.…”