海上低渗岩性油藏试井解释技术对策及其实施效果

Some technical countermeasures for the well test interpretation of offshore lithologic oil reservoirs with low permeability and their effects

海上低渗油藏测试存在井口产量低、压力恢复时间短、多解性突出等难题,试井解释难以得到准确的地层参数。提出了一系列海上低渗岩性油藏试井解释技术对策,主要包括:通过引入段塞流求取井口关井产量,增加可用的压力恢复段;利用反褶积技术叠加多个压力恢复段,延长压力导数曲线时间;采用数值试井模拟复杂岩性边界,减少解释的多解性。通过对南海东部地区某油田两口评价井的实际应用,验证了这些技术对策的合理性与可靠性,较好地解决了井口关井条件下低渗油藏难以达到径向流的试井解释问题。

It is difficult to obtain accurate parameters of formation from well test of offshore oil reservoirs with low permeability,because there are several problems such as low wellhead production,limited time of pressure buildup and obvious ambiguty in the well test of these reservoirs.Therefore,some technical countermeasures were proposed for the well test interpretation of these reservoirs,i.e.increasing available segments of pressure buildup by introducing slug flow to acquire shtu-in wellhead production,extending the time of pressure derivative curves by using the deconvolution technique to superimpose multiple segments of pressure buildup,and reducing the ambiguity by using the numerical well test to simulate complex lithologic boundaries.The reasonableness and reliability of these countermeasures were verified in their application to two appraisal wells in an oilfield in the eastern South China Sea,so the well test interpretation problem that an oil reservoir with low permeability is difficult to achieve the radial flow under the shut in wellhead condition was well solved.