合水长6超低渗储层水平井开发实践与认识

Practice and understanding of development with horizontal wells in ultra-low permeability Chang6 reservoirs of Heshui area

水平井作为一种提高单井产能的有效开发方式，广泛应用于长庆超低渗透和致密油储层，并实现水平井规模开发。然而在水平井实际生产过程中，通常表现出初期单井产量递减快、稳产难度大的生产特征，以长庆油田合水地区长6油藏水平井规模开发为例，统计分析发现该区水平井第一年递减达42．3％，递减较大，该生产动态特征严重制约了水平井采收率。针对合水长6超低渗油藏水平井单井递减较大的原因，油藏储层物性、压裂改造规模、注采井网和生产制度进行了递减因素分析，得出了储层物性影响水平井初期递减的主要因素。此外。结合递减主要和次要因素，提出了水平井开发长期稳产的技术思路和手段，为同类型油藏开发提供了宝贵的开发经验。

As an effective development method of improving the individual-well＇s productivity, horizontal well drilling has been widely used in the ultra-low permeability reservoirs and tight oil reservoirs in Changqing Oilfield, and has achieved large-scale development of horizontal wells. However, in actual production process, the horizontal wells usually present the production features of individual well＇s quick productivity decline and considerable difficulty in stable production during the initial stage. Taking the large- scale development with horizontal wells of Chang6 reservoirs in Heshui area of the Changqing Oilfield as an example, it is found by statistics aml analysis that the production decline rate of this area＇ s horizontal wells is up to 42.3% in the first year of production. This production performance seriously restricted the recovery efficiency of horizontal wells. In light of the reason for high decline rate of individual horizontal wells in ultra-low permeability Chang6 reservoirs in Heshui area, some factors leading-to-decline （physical properties of the reservoirs, scale of fracturing stimulation, injectors-producers pattern and production system） were analyzed, and it was coneluded that physical properties of the reservoirs are the major factor that affeets the initial decline in horizontal wells. Moreover, combining the principal and secondary factors leading to declining, the technical idea and means of long-term stable production in horizontal wells were presented. It can provide a valuable reference for development of the same type of reservoirs.