Evaluation of Three Large Scale ASP Flooding Field Test

Abstract

Scaling, emulsion breaking and high cost prevent ASP flooding going laboratory to field. When anti-scaling and produced fluid disposal challenges has been gradually solved in China after years of hard work, the sharp drop oil price makes prospect of ASP flooding dim again. However, ASP flooding is still very promising and has entered into commercial application in 2014 in Daqing. In 2015, the whole crude production from ASP flooding in Daqing was 3.509 million ton, 9.14% of the total production of Daqing oilfield (38.386 million ton). In 2016, there are more than 22 ASP flooding field projects active in Daqing, and the total ASP flooding oil production is 4.06 million ton, 11.11% of total oil production in Daqing. One of the three evaluated ASP flooding tests, ASP 1,2,3, is weak alkali (Na2CO3) based, the other two are both strong alkali (NaOH) based. These three tests shared four slug formulation, which is current standard practice in Daqing. Surfactants and polymers are all domestic. The total cost consists of construction investment, injected chemical fees (polymer, surfactant and alkali), operation fees including maintenance and repair fees, and water disposal fees. These costs are actual spending during ASP flooding tests. Though the ASP 1 and ASP 2 have the similar incremental oil recovery (30%) and both successful, the economic performances of weak alkali ASP flooding is much better for lower commuted total cost. Total cost of ASP 1 and ASP 2 is 28.2 $/bbl and 36.3 $/bbl respectively. The reservoir formation of ASP 1 and ASP 2 has many similarity, thus the difference can reflect alkali effects. ASP 3 has incremental oil recovery of 20.5% upon waterflooding, while it has much higher cost (49.5 $/bbl) than ASP 1 and ASP 2. This is attributed to the much higher polymer molecular and concentration injected, but less oil production. Though higher viscosity helps to overcome the severer heterogeneity as expected, it actually blocked the relative lower permeability formation. This tests shows that formation contamination is important issue to be considered. In high oil price era, the incremental oil recover can be regarded as core parameter since the cost increase can always be compensated by benefits of more oil, while in ultra-low oil price era, the balance between input and output is vital. Previous large scale ASP flooding field tests and current ASP flooding in practice shows that ASP flooding is still very promising even under such low oil price.