The Investigation Of Low Cost Tertiary Oil Recovery Technology On Jin-16 Block(western)

Over nearly 30 years of exploitation , Jin-16 block, the main totally water flooding fault block reservoir in Liaohe oilfield, now has been situated in development-decreasing condition characterized by high water cut and high recovery percent of reserves, approaching a water flooding depletion-type reservoir with only 0.63% of recovery rate. Therefore, it is imperative to enhance oil recovery by way of the transforming of development regime and the investigation of tertiary oil recovery. Nowadays polymers flooding technology has matured, for example, each year the oil production from polymer flooding accounts for 20% of the total production in Daqing oilfield. But for its high cost, it is practically important to carry out the investigation on tertiary oil recovery in order to achieve the maximum economic benefit .Thus ,three well groups were selected for investigation on low cost tertiary oil recovery, that is weak gel activated water profile controlling and flooding ,aiming to economically improve oil recovery of the in-test well groups, furthermore , to supply technical reserves for the whole Jin-16 block and others fault blocks where tertiary oil recovery may spread .In this research, an accurate 3D geological model is established for the investigation of low cost tertiary recovery through the reservoir description of the pilot test zone. The evidence for tertiary recovery in the pilot test is strengthened by means of evaluation on water flood effect and through thorough study of the water flooding character and the flowing behavior of the oil-water-gas system; The optical pilot test design is provided basically on the residual oil distribution during high water cut period and relatively high residual oil saturation zone; The best formula system for the pilot test is determined by way of indoor tertiary recovery experiments:'0.1%HQ + 0.05%(AC + JB + LA)'for gel profile controlling and'0.6%NaOH+0.2QYJ-7'for flooding system , resulting additional 12.85% of oil displacement efficiency. Using reservoir engineering methods the tertiary recovery test zone is arranged: 3 chemical reagent injection wells,2 central effected wells, and 6 periphery observation wells are devised ,with controlled oil-bearing area of 0.48km2 and petroleum geologic reserve of 208×104t. Also the numerical simulation software is used to predict the development effect of the optical test plan and the economic evaluation performed provides scientific basis for the test decision : weak gel activated water profile controlling and flooding can enhance 7.9% oil recovery than water flooding does and increase recoverable reserves of 16.4×104t with input-out-ratio of 1:3.