堵酸结合改善注水井吸水剖面

本文针对调剖、酸化技术对剖面改善作用相对单一,效果受作用机理和地层层间渗透率差异等因素的限制,且调剖、酸化施工过程中,堵剂、酸液可能进入非目的层,导致低渗透层被堵剂污染或高渗透层被酸液解堵,以致吸水剖面进一步变差的现状,提出了封堵与酸化结合改善注水井吸水剖面新工艺,利用调剖-酸化两种工艺的协同作用,最大限度地缩小层间渗透率级差,提高吸水剖面的均匀程度和水驱动用效果的工艺技术。通过室内评价,筛选出了适合不同渗透率地层封堵需要的强堵、弱堵、暂堵三类堵剂和针对不同污染的地层复合解堵酸体系,并优化出了一套相应的选井原则和施工工艺。2001年至2002年底,现场实施46井次,可对比吸水剖面13口井,平均单井吸水厚度增加3.4m/1.4层。累计增油10519吨,投入产出比1∶3.5。

Combination of Plugging and Acidization Improves Injection Profile

Plugging agent treatment and acid stimulation have completely different mechanisms for improving injection profiles. In this paper, a hybrid procedure is introduced to reduce the damage of the plugging agent to low and medium permeability zones and the penetration radius of acid into high permeability zones. The procedure is: First inject plugging agent to block high permeability zones, and then inject acid to remove plugging agent damage from the low and medium permeability zones and stimulate them. To perform this procedure successfully, three kinds of plugging agents, namely strong strength plugging agent for the wells with fractures or high permeability streaks, weak gel for those with thick layer in which serious heterogeneity exists, temporary plugging agent for those in which the absorption ability of high permeability zones needs maintaining, were screened out for use in different reservoirs. Several acid systems were evaluated to be compatible with the three kinds of plugging agents. The objectives of this paper are:(1)To show the screen results about the compatible plugging agent and acid; 2 To show how to optimize the operation process;(3)To tell some experience gained ( ) from the oilfield applications of this technique. From Jan. 2001 to Dec. 2002, 46 operations using this procedure were carried out in Weicheng and Mazhai Oilfields of SINOPEC. Results show that the average benefit/cost ratio is over 3.5. Experience acquired from these applications was summarized in the paper.