下二门油田非均质大孔道油藏聚合物驱油矿场试验

A polymer flooding pilot test in a strongly heterogeneous reservoir of Xiaermen oil field.

下二门油田H2 Ⅱ油组具有非均质性严重、大孔道发育、水油流度比高的油藏地质特点。注水开发时 ,油井见水早、含水上升快、水驱波及效率低 ,造成水驱开发效果差 ,水驱采出程度仅为 2 4 %。对此开发出高强度调剖剂进行油层深部调剖 ,整体封堵水窜 ;同时筛选适用于污水配制的超高分子量的聚合物(HPAM分子量 :2 0× 1 0 6～ 2 8× 1 0 6) ,增加驱替液黏度 ,改善油水流度比 ,提高波及体积和开发效果。该矿场试验把调剖和聚合物驱两项技术结合在一起 ,共设计 7口注聚井、1 8口生产井。注聚合物前 ,全部注入井实施整体深度调剖 ,平均调堵半径大于30m ,有效地遏止了大孔道窜流 ,使后续聚合物溶液能较均匀地进入油藏剖面 ,确保了聚驱效果。目前已注入聚合物段塞 0 .39PV ,累计增油 9.39× 1 0 4t,阶段提高采收率 6 .5% ,达到了矿场试验预测的开发指标 ,开发效果得到明显改善。图 2表 3参

The H 2Ⅱzone in Xiaermen oil field is characterized by severe heterogeneity, large porous channels and high mobility ratio of water over oil. During waterflooding, water easily makes a breakthrough to oil wells, then the water cut increased swiftly, causing low sweep efficiency of waterflooding and waterflooding's recovery only 24% of OOIP. For this reason, a stronger agent of profile modification was developed to block thief zones in whole reservoir. Meanwhile, an ultra high molecular weight polymer (polyacrylamid molecular weight: 20×10 6 -28×10 6 ) was selected, which suits for being dissolved in produced water, to increase water viscosity, to correct the high permeability variation and adverse mobility ratio. Perfectly combining the technology of high strength profile modification with polymer flooding, the pilot test performance has been carried out in 7 injection wells and 18 production wells. Before injecting polymer, the profile modification for all injection wells has been accomplished to block the large porous channels efficiently. Before polymer injection, depth profile modification was carried out in all injectors, the average radius of the profile improvement is more than 30m, cross flow of big pore throat was effectively held back, resulting in the follow up polymer liquid evenly entering into reservoir layers, which shows this is an effective method. At present, the injected polymer slug is 0.39PV, the total increase of oil production is 9.39×10 4 t, the current recovery increase is 6.5% OOIP. The polymer flooding test has met expected development goal. The economic benefit of the development has been improved obviously.