利用无线传感器技术的新方法可以显著提高弃置井的评价水平！ 编译 | 惊蛰 获得和解译弃置封堵深水评价井的长期压力积聚数据对于深水作业意义重大，为了完成这个目标，作业团队必须要考虑成本问题，得益于新的测井方案、无线传感器及材料平衡技术，完成了该井*-**个月内油藏压力数据收集和解译，测试井使命成功达成。 利用三种复杂性增加解译方法来描述储层。 首先，使用物料平衡来估算最小连通储层体积，其优势在于只需要输入几个预估值，就可以产生高可信度的结果。其次，利用压力瞬态分析软件中的分析模型，研究近井筒区域特性和油藏边界距离。最后，使用有限元差分模拟模型来研究整个油藏的储层性质和非均质性。随着模型复杂性增加，也能获得储层特性和体系结构的更多了解，方案灵活性就有所增加。 压力数据解译关键难点之一是传感器的不确定性，这会导致三种解译方法结果不确定性增加。根据常规测试井设计（具有不同的流速和累积周期）分析，解决关键不确定性问题的成本超过了信息本身的价值。为了证明评估的合理性，需要一种方法来延长流动期或压力积聚期，而无需使用钻机或保持井处于永久性废弃状态。 为了实现这一目标，作业团队评估了无线测量技术扩展压力积聚时长的潜力。当前主要有两种无线技术，即声学和电磁传输，都通过管道/外壳实现数据传送。区别在于声波传输要使用电缆穿过固井水泥，这违反了弃置井的屏障标准。因此，最终选择了电磁传输。 此次设计的一个主要特征是冗余的传感器（*个）、中继器（*个）和海底调制解调器（*个）使用，以确保无线系统内不存在单点故障。由于各个仪表的响相互独立且相同，这种设计也保证了仪表的测量精度，不确定性范围缩小。数据分三批从无线仪表中回收（可通过作业船只实现），海底调制解调器作为最后一部分回收到表面。 良好的测试设计需要初始清理流程、初始压力构建、多速率测试、高速流动周期和最终的压力积聚。出于操作原因，需要在延长的流动期间额外补充甲醇抑制水合物生成。最终的建设分为三个部分：在最开始的**小时内完成传统钻井测试（DST）测量仪记录，提供可以解译的高频数据（地层渗透率和厚度）和近井筒特征。随后，在安装和调试长期无线测量系统的同时，短暂中断数据记录。最后阶段是无线传感器数据的长期采集，相比于常规工具，其采集频率低得多。 在获得高频传感器数据后，作业人员获得了更精确的信息，包括油藏渗透率、岩层均一性等。此外，无线传感器还提高了评价同意区块不同甜点的边界分布，分辨能力更高。通过利用传感器数据，解译获得的数据提高了预测范围，最长边界距离提高至**km。完整的测试压力匹配表明，分析模型中的气体体积显着高于实际的气体体积，这与此前对这种沉积环境的理解是一致的。 相比于传统的DST，在无线传感器的帮助下，压力积聚时间显著改善，这有助于作业人员更准确的评估油藏储量等信息，并于之前的作业计划进行对比，实现优化。 作业团队的结果表明，虽然解译方法复杂性有所增加，却能从传感器数据中获得更多的油藏信息。总之，复杂技术提供了额外的见解，但最简单的技术可以为其结论提供更高的可信度。? This paper describes the acquisition and interpretation of long-term pressure-buildup data in a plugged and abandoned deepwater appraisal well. To accomplish the test objectives at an acceptable cost, a novel combination of well testing, wireless-gauge technology, and material-balance techniques was used to allow the collection and interpretation of reservoir-pressure data over a planned period of * to ** months following the well test. The final buildup duration was *** days (** months). Three interpretation methods of increasing complexity were used to provide insights into the reservoir. First, material balance was used to produce an estimate of the minimum connected reservoir volume. The advantage of material balance is that it requires very few input assumptions and produces a high-confidence result. Second, analytical models in commercial pressure-transient-analysis software were used to investigate near-wellbore properties and distances to boundaries. Finally, finite-difference-simulation models were used to investigate reservoir properties and heterogeneity throughout the entire tested volume. With increasing model complexity came additional insights into the reservoir properties and architecture but reduced solution uniqueness. A key complication for the interpretation of the recorded pressure data was the potential for gauge drift. This was incorporated into the uncertainty range used in all three interpretation methods. Analysis of conventional well-test designs (with varying flow rates and buildup periods) showed that the cost of resolving the key uncertainties exceeded the value of information significantly. To justify the appraisal, a way was needed to extend either the flow period or the buildup period without a rig on station and with the well left in a permanently abandoned state. To meet this objective, the potential of wireless-gauge technology to extend the buildup length was evaluated. Two competing wireless technologies were available, acoustic and electromagnetic transmission, both occurring up the tubing/casing. The key differentiator was that acoustic transmission required that cables be run through any cement plugs, which violated the barrier standards for abandoned wells. Accordingly, electromagnetic transmission was selected for the final system. The post-abandonment well concept is shown in Fig. *. Of note is that the wellhead was not recovered and the top of the **- and **-in. casings have not been severed. One critical design feature was the use of redundant gauges (four), repeaters (four), and subsea modems (four) to ensure no single point of failure existed within the wireless system. This also resulted in a narrowing of the gauge-drift and accuracy-uncertainty range as the response of individual gauges was thought to be independently and identically distributed. Data were recovered from the wireless gauges in three tranches (corresponding to visits by a supply vessel to the well vicinity), with the subsea modems recovered to surface as part of the final tranche. The well-test design called for an initial cleanup flow, initial buildup, multirate test, extended high-rate-flow period, and a final buildup. For operational reasons, an additional shut-in during the extended flow period was necessary to restock methanol for hydrate inhibition on the rig. The final buildup was split into three components: The first ** hours were planned to be recorded with conventional drillstem-test (DST) gauges run on the completion to provide high-frequency data that could be -interpreted for kh (the product of formation permeability and thickness) and any near-wellbore features. This was to be followed by a break in the recorded data while the long-term wireless-gauge system was installed and commissioned. The final stage was the long-term buildup recorded by the wireless gauges, which had a much lower acquisition frequency. Interpretation of the high-frequency-gauge data provided information on the skin and non-Darcy skin, formation permeability, heterogeneity (through indications of two-layer behavior with crossflow away from the wellbore), and the two closest boundaries. Inclusion of the wireless-gauge data also allowed for resolution of the third boundary and provided an indication of the location of the fourth boundary, but the derivative response at the time of the last data point was still not indicative of a fully bounded system. Inclusion of the wireless-gauge data in the interpretation increased the distance investigated by the well test by a factor of ten, with the final path length to the outermost boundary estimated to be ** km. The full test pressure match, however, indicated that the gas volume within the analytical model was a significant overestimate of the actual gas volume, which is consistent with the authors’ understanding of this environment of deposition. Use of wireless gauges allowed the buildup duration to be extended from the * days used on previous DSTs in the region to *** days, with the available rig day allocation used to produce a larger-pressure perturbance. This allowed the well test to investigate a reservoir volume similar to planned development wells (with the outermost boundary being ** km from the well). This paper shows how a progression of interpretation techniques of increasing complexity allowed additional insights to be drawn from the collected data but at the expense of increasing complexity, more degrees of freedom, and additional external constraints. While the more-complex techniques provide additional insights, the simplest technique provides a higher degree of confidence in its (more-limited) conclusions.