Alkline/Surfactant/Polymer (ASP) Commercial Flooding Test In Central Xing2 Area of Daqing Oilfield

Abstract

Abstract

The industrial test study on ASP-flooding in the middle part of Xinger area of Daqing oilfield is based on a lot of laboratory[1] and numerical simulation studies. By optimizing formulations, the chemical usage in the ASP system reduces significantly, surfactant, polymer, and alkli decrease by one third, nearly one second, and one sixth respectively, with 1.47×108 RMB being saved only for the chemicals. The variation regularity of the ASP-flooding performance is analyzed preliminarily by combining the injection-production profile, the concentration of the produced chemicals, the produced concentration of various ions, and the performance variation (such as the daily fluid production rate, oil production rate and water cut) in the test area with the accurately geological study. At present, the obvious response to increasing oil and decreasing water cut is seen in the test area, 0.22PV ASP system has been injected in the whole test area, and the oil displacement response is seen in 19 producers. The oil displacement response is seen in all 9 central producers, the daily oil production rate increases from 25t before response to 148t, and the daily incremental oil production rate is 123t. The comprehensive water cut decrease from 96.3% before response to 69.9%, decreasing by 26.4 percentage points. The extent of water cut decrease is above 30 percentage points in 5 producers, among which the largest extent is up to 56.9 percentage points. Now, the performance response of the central well area is basically in agreement with the results prediced by the numerical simulation, expecting that the ASP-flooding oil recovery can be 21.52% (OOIP) higher than the waterflooding.

Introduction

For the ASP-flooding technology of Daqing oilfield, on the basis of a lot of laboratory and numerical simulation studies,3 ASP-flooding pilot field tests were conducted successfully in the west part of the central area[2], the central block of Xingwu area, and the area[3] with small well spacing of Daqing oilfield before and after 1993, achieving the good results that the ASP-flooding oil recovery can be 21.4%, 25% and 23.24% (OOIP) higher than the waterflooding respectively. Before and after 1996 two ASP-flooding expension field tests were conducted in the west part of Xinger area[4] and Beiyiduanx[5] of Daqing oilfield, achieving the good results that the ASP-flooding can be 19.24% and 21.04%(OOIP) higher than the waterflooding respectively. Especially for the ASP-flooding expansion field test, under the condition that the water cut in the central producers is high for a long time, the satisfied result that the ASP-flooding oil recovery still can be 19.24%(OOIP) higher than the waterflooding is obtained, which fully confirms that the ASP-flooding mainly improves oil displancement efficiency while enlarging sweep volume. In order to further study the oil displacement efficiency of the ASP-flooding under the condition of the wide spacing, the multiple well group, and the large slug with low concentration, the first industrial ASP-flooding test in the world was carried out in the middle part of Xinger area of Daqing oilfield in 1998 to further verify the economical efficiency of the ASP-flooding techonogy and a complete set of the matching ASP-flooding technology, such as the allocating injection process, the injectivity and the productivity, the performance variation regularity of the oil and water wells, the gas lift process, and the processing technology for the produced water, providing the theoretical and practical basis for the industral deployment of the ASP-flooding.

General Situation of Test Area

The test area is located in the middle prat of Xinger area of Xingbei oilfield, extending from Fault 202 in the north to Row 30 of Xinger area in the south, and bounding Fault 214 in the east and Well 27 on Row 27 of Xinger area in the west. The five spot pattern is used, the injection-production well spacing is 250m, and the test target is PI21–33. There are 45 producers and injectors altogether, among which the injectors are 17, the producers are 27(the central ones are 9), and the sampling and observation well is 1 (see Fig.1). The associated information about the test area is seen in Table 1.