Decision of implementing two polymer-augmented waterflooding pilots in Daqing was taken in 1987 considering favorable laboratory results and preliminary reservoir studies. Since that date, the drilling of 8 injectors and 18 producers representing 4 inverted five-spot for each pilot has been achieved.
The formation is composed of different superimposed reservoirs. Each reservoir itself is constituted of numerous embedded sand and shale layers, characteristic of fluvio-deltaic deposits. Pilot PO is devoted to one reservoir while polymer injection in pilot PT will be simultaneously performed in two reservoirs which has been found to be more representative of injection conditions in Daqing. Oil viscosity is 9.5 cp.
Drilling was accompanied by an intensive program of data collection such as electric logging, coring, DST and interference tests. The paper presents how these data have been interpreted in terms of geological deposit to give the best possible vertical and areal description of each reservoir as well as their integration in the 3D chemical model SARIP designed by IFP. Polymer injected is HPAM at a concentration of 915 ppm.
The paper discusses the different results of simulation, focusing on fluid and polymer production profiles and areal distribution in each reservoir.
The predicted range of incremental oil recovery inherent in polymer is dependent on the severity of the reservoir heterogeneity and varies from 7.5% in stratified areas to 12% when the formation is more homogeneous. This indicates a better polymer efficiency to reduce the detrimental water-oil mobility ratio than to correct the rock permeability profile.
The paper ends by a presentation of the first field production results of the pilots that were put in stream in 1989.