Laboratory Research On Completion Fluid In Sa 0 Group

Sa 0 group in Daqing is a low permeability reservoir and has high content of dirty sand. In the completion process, if the incompatible completion fluid with reservoir enters into the reservoir, the reservoir will be damaged. Before developing Sa 0 group, developing a new kind of completion fluid for Sa 0 group is very necessary.This paper takes Lamadian oilfield as an example, analyzing the reservoir characteristics and reservoir sensitivity of the Sa 0 group. The reservoir sensitivities of Sa 0 group are weak velocity sensitivity, strong water sensitivity, strong salt sensitivity, strong acid sensitivity, strong medium alkali sensitivity, so Sa 0 group is a strong sensitivity reservoir. Reservoir protection problems are prominent. So it is necessary to study a kind of high inhibitive completion.This paper evaluate the performance the three common completion fluid, the experimental results show that solid-phase particles is the important factor which cause reservoir damage, so it is ignored, developing free solid-phase or low solid-phase completion fluid is necessary.Through analyzing the reservoir characteristics and reservoir sensitivity of the Sa 0 group, and evaluating the formation damage the three common completion fluid cause, research shows the major formation damage mechanism: firstly, incompatibility of completion fluid and the reservoir fluid; secondly, incompatibility of completion fluid and the reservoir rocks; thirdly, the invasion of solid-phase particles; fourthly, water blocking effect; fifthly, chemical adsorbability and wettability; sixthly, particles migration.For the main factors causing Sa 0 group damage, we develop a kind of low damage completion fluid for Sa 0 group. Research focused mainly on choosing completion fluid additives, such as antiswelling agents, friction agents, cleanup additives, corrosion inhibitors, etc. Eventually we optimize the basic formulation of the completion fluid system for Sa 0 group: water + mini-cationic antiswelling system (0.6% mini-cationic polymer A +2.0% KC1 + 0.5% AlCl₃) + 0.5% friction agent PEG400 + 0.5‰cleanup additives BNP-10 + 0.5%o corrosion inhibitor HS-1.We evaluate the performance of the completion fluid system, completing it with the three common completion fluid, the new completion fluid has the characteristics of high inhibitory, corrosion resistance, stability and low damage, which can protect reservoir very effectively. For the development of this low permeable reservoir such as Sa 0 group, the new kind of completion fluid system we developed provides the basis in completion reservoir protection.