History and Actuality of Separate Layer Oil Production Technologies in Daqing Oilfield

Abstract

Abstract Separate layer oil production technologies in Daqing Oilfield were developed and improved continually with the course of the oilfield development. The technologies in the medium-low water-cut flowing period were mainly composed of the oil well packers, the Model 625 oil well regulators and the multipurpose eccentric regulating & plugging control system. In the early high water-cut artificial lifting period, 4 types of mechanical water shutoff technologies including integrated, equilibrium, slip and drillable ones were developed and applied. Furthermore, the double fluid chemical water shutoff technology was successfully studied. In the late high water-cut artificial lifting period, the water detection technology by temperature log and the profile testing technology provide accurate guides in determining the high water-cut layers. Adjustable intervals mechanical water shutoff technology and the single fluid chemical water shutoff technology could meet the requirements of subdividing oil production and water shutoff for artificial lifting wells. 1. Introduction Daqing Oilfield is a heterogeneous multi-layer sandstone reservoir, whose exploitation strategy is to inject water to keep the reservoirs' pressure. The major oil reservoirs' physical properties are quite different from the secondary ones. During the water injection process, the water & oil distribution and the rule of their motion are extremely complex, commingled production method could lead the injected water underground easily to be finger advanced. Therefore separate layer oil production technologies that are suitable to Daqing Oilfield's real situation were developed in order to reduce these differences among layers, control rising water-cut, fully exploit each single oil layer, and provide vital technical support for high-efficiency oilfield development. Separate layer oil production technologies in Daqing Oilfield were developed and improved continually with the course of the oilfield development, which were fallen into three successive ones: the medium and low water-cut flowing period; the early high water-cut artificial lifting period and the late high water-cut artificial lifting period. This paper briefly introduces the development of separate layer oil production technologies in terms of each period's characteristics, and also presents the future developing direction of Daqing Oilfield. 2. The medium-low water-cut flowing period This period began from the early days of the oilfield exploitation to the end of the 1970s. At that time, the major exploiting reservoirs in Daqing Oilfield were high permeable layers in the main pays and the medium-high permeable layers in the nonpay zones. The separate layer oil production mainly aimed at controlling the injection into the high permeable layers, increasing the injection into the medium-low permeable layers and regulating the distribution of oil and water among layers and planes by the way of separate layer water injection. Therefore, the production from the medium permeable layers could compensate the production from the high permeable ones. When most layers produced water in oil wells and the high permeable oil reservoirs entered into the high water-cut period, it was necessary to enhance the development for medium-low permeable layers in order to reduce the differences among layers. Meanwhile, separate layer oil production and water shutoff measures were taken for high water-cut intervals. The separate layer oil production technologies in the 1960's, which were mainly composed of the oil well packers and the Model 625 oil well regulators, can divide the reservoirs into 4–5 intervals. Adjusting the size of unfixed nozzles in the Model 625 regulators can control each layer's production. As a result, the wells can produce oil from separate intervals quantitatively. The separate layer oil production technology with the Model 625 oil well regulators can effectively ease the contradiction among layers; exploit each oil layer with proportion rate; control the increasing water-cut rate; enhance the production and increase the recovery ratio. It has been applied at more than 2000 wells on site.