基于生产测井的多层试井解释技术

致密砂岩气井为了获得工业产气量,常常采取多层分压合采措施,常规试井解释由于采用平均化的单层试井解释模型,容易造成解释结果无法反映各个产层的真实信息。为此,基于鄂尔多斯盆地致密砂岩气田某井4个产层分层压裂后开展的268 h的压降测试、468 h的压力恢复测试和生产测井数据,采用单层试井解释模型和多层试井解释模型分别对其进行解释,其中多层试井解释模型结合生产测井解释成果引入分层产量数据作为新增约束条件,对多层合采气井进行精细试井解释。结果表明:(1)3种单层试井解释模型均等同于将该井4个层位的参数平均化,各项指标均拟合较好,反映了单层试井解释模型具有多解性;(2)多层试井解释录入各层储层物性参数,并引入分层产量作为拟合约束条件,其压力及压力导数双对数曲线拟合、单对数曲线拟合、压力史拟合和分层产量拟合均较好,能够获得各层的表皮系数、裂缝半长、渗透率及边界等数据。结论认为,采用多层试井解释模型降低了合采气井试井解释结果的多解性,定量评价了各储层的参数,为类似储层的针对性措施和动态描述提供了参考。

Multi-layer well test interpretation technology based on production logging

The process of separate-layer fracturing & commingled production is often used in tight sandstone gas wells for commercial production. The averaged single-layer well test interpretation model is adopted for conventional well test interpretation, so the interpretation results cannot reflect the true information of each pay zone accurately. In this paper, after the separate-layer fracturing & commingled production, drawdown test (268 hrs.), build-up test (468 hrs.), and production logging were conducted in 4 pay zones of a certain well, all the data of which were interpreted by using the single-layer and multi-layer well test interpretation models, respectively. It is shown that in 3 types of single-layer well test interpretation models, the parameters of 4 pay zones in this well are averaged and all indexes are well fitted, indicating this model’s ambiguity. Besides, in the multi-layer well test interpretation model, the separate-layer production rate was introduced into the production logging interpretation results as an additional constraint to carry out fine well test interpretation on multi-layer commingled gas producing wells. And the log–log curves and log curves of pressure and pressure coefficients, the pressure history and the separate-layer production rates are well fitted, and the parameter values of each layer are obtained, such as skin factor, half fracture length, permeability and boundary. It is concluded that by virtue of multi-layer well test interpretation, the ambiguity of well test interpretation results of commingled gas producing wells is reduced and the parameters of each reservoir are evaluated quantitatively. This research result provides guidance for the production proration of gas wells.