砾岩油藏聚合物驱水流优势通道特征及其对剩余油的影响

针对QD1油藏克下组砾岩油藏含水上升快、产液速度高的问题,运用Rdos软件栅状模拟和Eclipse化学驱模拟刻画聚合物驱不同阶段水流优势通道及其与剩余油分布关系。结果表明:QD1油藏克下组油藏水流优势通道可分为2种类型,在聚合物驱4个阶段中,前缘水驱阶段和回返递减期分别发育6条和17条Ⅰ类通道,集中于水平压裂缝和储层相对高渗带,见效高峰期和聚合物驱稳产期以近东西向的Ⅱ类通道为主;水流优势通道是控制克下组砾岩油藏剩余油分布的重要因素,研究区东部剩余油呈鸟足状、环岛状分布在水流优质通道间,随水驱波及范围扩大,剩余油缩小为团块状、点状,西部剩余油则呈带状、线状分布在断层附近。该研究为QD1油田水流优势通道封堵措施设计、改善砾岩油藏聚合物驱效果提供依据。

Characteristics of Preferential Migration Pathway of Polymer Flooding in Conglomerate Reservoirs and Its Effects on Remaining Oil

To address the problem of high water cut increasing rate and high fluid production rate in the conglomerate reservoir of Kexia Formation of QD1 reservoir, grid simulation with Rdos software and Eclipse chemical flooding simulation were conducted to characterize the preferential migration conduit and its relationship with remaining oil distribution in different stages of polymer flooding. The results show that the preferential migration conduit in Kexia Formation of QD1 reservoir was divided into two types. In the four stages of polymer flooding, 6 and 17 Type I conduits were developed in the front water flooding stage and the return regression stage respectively, and were concentrated in horizontal fractures and the relative-high-permeability area of the reservoir; Type II conduits were mainly developed in the near east-west direction in the effective peak period and the stable production period of polymer flooding; preferential migration conduit was an important factor to control the distribution of remaining oil in conglomerate reservoir of Kexia Formation; the remaining oil in the east of the study area was distributed in preferential migration conduit in the shape of bird foot and island; with the expansion of water flooding range, the remaining oil was reduced into clumps and spots, while the remaining oil in the west was distributed in a strop or line shape near the fault. This study provides a basis for the design of plugging measures for preferential migration conduit in QD1 oilfield and the improvement of the polymer flooding effect in conglomerate reservoir.