Oil & Gas Geology ›› 2005, Vol. 26 ›› Issue (5): 623-629.doi: 10.11743/ogg20050511

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Development strategy of fractured-vuggy carbonate reservoirs—taking Ordovician oil/gas reservoirs in main development blocks of Tahe oilfield as examples

Chen Zhihai1, Liu Changhong1, Yang Jian2, Huang Guangtao1, Lu Xinbian2   

  1. 1 Exploration and Production Research Institute, SINOPEC, Beijing;2 Northwest Branch Company, SINOPEC, Urumqi
  • Received:2005-07-09 Online:2005-10-25 Published:2012-01-16

Abstract:

Ordovician reservoirs in Tahe oilfield are typical fractured-vuggy carbonate reservoirs of fossil karst type.Progressive exploration and development pattern was adopted in the initial stage of development.Reserves were brought into production stage by stage.Vertical well pattern combining the selected "spots,lines and the whole area" was applied to control the reserves.Reservoir prediction and identification technologies with extraction and analysis of seismic attribute as the core,as well as strong acid fracturing and sidetrack horizontal drilling technologies were successfully applied in development.Success ratio of development well increased from below 60% to over 85%,discovered oil reserves in place exceeded 500 million tons,and annual production capacity of the oilfield reached 3.5 million tons.However,several factors have influenced further improving development effects along with progress of oilfield development,such as inadequate understanding of the features of fractured-vuggy reservoirs,low reliability of discovered oil reserves,and lack of measures to enhance oil recovery and single well production capacity in mid-and late-development stages.To solve these problems,the following measures should be taken in future oilfield development:(a) compilation or adjustment of development program should be made on the basis of producing reserves or recoverable reserves;(b) enhancing control over reserves by applying combined vertical and horizontal well pattern;(c) redividing development blocks;(d) determining rational well numbers according to single well controlled reserves;and(e) determining individual well's production proration according to rational producing pressure drop.

Key words: Tahe oilfield, carbonates, karst, development strategy, development example

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