Enhanced Oil Recovery Research Of TaZhong 4 Oilfield In Low Reserve-production Rate Stage

Reserve-production ratio is referred as the ratio of the remaining recoverable reserves and annual production of one country, a region or an oil and gas field in a year. Reserve-production ratio can reflect an important ratio relation in the internal of oil industry, and apply an important indicator for analying and judging a reasonable development and construction size, production form and stable situation in the development of oil and gas field. Through the reserve-production ratio can analyze and determine which development phase the oil field is in, stable level and resources assurance level. If the reserve-production ratio is too large, the funds will be backloged in the form of reserve existence, if the reserve-production ratio is too small, the assurance level of production will be low. Determine a reasonable reserve-production ratio, can not only ensure a normal increase in crude oil production, but also a reasonable investment for oil and gas exploration. Thus, it is extremely important to study reserve-production ratio for oil industry.In this paper, based on the crude oil properties and formation characteristics of Tazhong 4, for the problems existed in Tazhong 4 oil fields, we mainly do the following works:1. Analying the characteristics of reserve-production ratio at this stage of Tazhong 4 Oilfield, identified the characteristics of reserve-production ratio at this stage. We believed that from the analysis the currently oil reserve-production ratio is far below the stable limit reserve-production ratio, the rapidly declining oil production is a concrete manifestation of the normal development law in oil fields. The possibility of Tazhong 4 Oilfield to maintain a stable production in the premise of current low reserve-production ratio is small, so the total adjustment principle should be based on the slow decline,and ensure that the production decline as smooth as possible.2. Analying the development effect of Tazhong 4 Oilfield under the low reserve-production ratio, we believed that the period of no water and low water cut oil production time is long, the initial capacity is larger, development effect is better, homogeneous sandstone paragraph is significantly better than the pebbly sandstone paragraph; the energy of homogeneous sandstone remained stable, pebbly sandstone paragraph formation pressure fell too fast; contradiction between layers is prominent. So we propose to mining stratified 1, 2, 3 layer, 4, 5 layer and homogeneous sandstone layer.3. Determining the remaining oil distribution of Tazhong 4 oilfield by the application of experimental methods, reservoir engineering methods and numerical simulation, TZ4 remaining oil field types include: injection-production imperfect, interlayer interference, crosshole stranded, fault block, laminated interference. Injection and production imperfect and interlayer interference is the major factor in the formation of residual oil. The reserves accounted for 77.7 percent of the remaining reserves, and the main direction of the remaining oil potential is in the injection-production imperfect and interference layer; TZ402CIII homogeneous sandstone paragraph oil recovery is high, residual oil are mainly distributed in the axis; pebbly sandstone paragraph oil recovery is low, the distribution of remaining oil is into a plane.4. On the basis of development evaluation, determine the adjustment countermeasureBased on the low reserve-production ratio development stage of blocks in TZ4 Oilfield TZ402 block CIII oil group pebbly sandstone layer 1,2,3,using vertical well ring plus point water injection to adjust can meet the best effect, recommend "8 inject 17 product" vertical well injection and production adjustment programs; CIII oil group layer 4 below using horizontal wells exhaustion development means can meet the best effect, recommend staggered arrange wells (5 wells) along the axis adjustment programs; CIII oil group pebbly sandstone layer 1 is proposed to use current and subsequent well pattern to adjust crossing well paragraph to adjust potential wells; through numerical simulation and analysis of dynamic data, this paper argues that gas cap occurred gas channeling in the vicinity of 1998, and occurred contraction after the first expansion process. TZ402 block CIII oil gas cap index is 2.3 now, which has a small influation for development effect, so we recommended not to consider gas cap protection separately.