Laboratory Research On Chemical Flooding Through Horizontal Wells Combined With Vertical Wells After Polymer Flooding

Horizontal well is a technology by enlarging drainage area to improve production of oil wells. Compared with vertical well, horizontal well has the property of lower producing pressure differential and higher production. Based on the matured technologies in horizontal well and chemical flooding in Daqing oilfield, the feasibility of chemical flooding with horizontal wells and vertical well to enhance oil recovery after polymer flooding was studied in lab in this paper. The best well pattern mode was optimized through evaluating EOR capability of SP flooding under different well pattern modes, which provide guiding suggestions for field application.Three-dimensional physical model of positive rhythm was developed according to practical geologic property of Sazhong development zone. Experiment study of EOR of SP flooding after polymer flooding with vertical well and horizontal well was carried out on this model. Compared increasing degree of recovery, water cut changing and pressure changing of different well pattern modes, it is found that increasing degree of recovery of one-well injection and one-well production of horizontal well is the highest, that of one-horizontal well and one-vertical well injection and one-horizontal well and one-vertical well production is the lowest, that of tow-horizontal wells injection and five-vertical wells production, five- vertical wells injection and two-horizontal wells production and one-well injection and four-wells production of vertical wells are between them. The best well pattern of SP flooding after polymer flooding is one-horizontal well injection and one-vertical well production, which can improve recovery to 17.69 per cent.