Abstract
Perforating as a widely-applied stimulation technology is becoming incrementally important in unconventional oil/gas development. It can effectively improve deep-lying high-temperature, high-pressure (HTHP), low-porosity, low-permeability reservoirs, eliminate near-wellbore surface pollution, and increase drainage area. Characteristics of damage zone porosity directly reflect perforating performance. To study porosity and permeability of damage zone in sandstone targets, the paper collected sandstone cores from the 3rd section of the Zhuhai Formation to conduct a simulation experiment for HTHP perforation of large-size targets. After the simulation experiment, an automatic scanner was used to find the planar distribution of the porosity and permeability parameters of the 150°C perforation holes in the cores. The study led to two findings. First, the temperature has a minor effect on the hole depth and diameter in a specified scope. The hole depth decreases as the negative pressure increases and the depth decreases as the effective stress increases. Second, a UHP perforated sandstone target is remarkably zone-specific in planar distribution of the hole porosity and permeability. The damage zone can be divided into the fracture zone, the transition zone, the compaction zone and the undisturbed zone. Besides, the zone permeability damage was quantified. These findings can effectively support research on numerical value simulation for HTHP perforation holes. Besides, they can support HTHP well perforating design and improve near-wellbore permeability enhancement and plug removal.
Highlights
Sandstone cores were extracted from the 3rd section of the Zhuhai Formation to physically simulate a large-size hole experiment which primarily studies the effect of three reservoir characteristics, such as temperature, negative pressure condition and effective formation stress, on the result of the perforating experiment
The analytical findings show that the fracture zone accounts for 8.3% of the scanned area of the target, the transition zone accounts for 8.5% of the scanned area, and the compaction zone accounts for 24.2% of the scanned area
This paper involves sandstone cores extracted from the 3rd section of the Zhuhai Formation to study the multidimensional porosity characteristics of the damage zone in sandstone target holes in different reservoir conditions
Summary
Quite a few perforated completion techniques have been developed for reservoir development (Zhu, et al, 2015) in China and beyond. Every 6.9 MPa increase in compressive strength causes a 5–7% decrease in the average hole depth This suggests that characteristics of different concrete targets have a major effect on the test results. In 2011, Grove et al, 2011 first summarized the inadequacies of the existing test and analysis methods in regard of CFE (Core Flow Efficiency) computation, concluding that the original methods generated greater errors They developed more reliable test methods and data processing methods to compute the flow efficiency, the effective permeability and FIGURE 1 | Final experimental sandstone targets (Φ400 mm). Perforating simulation test has been broadly applied in perforating parameters acquisition, reservoir damage mechanism research, penetration depth-affecting factor evaluation, perforation hole geometry research, hole flow efficiency evaluation, bullet performance analysis, and evaluation of the effect of perforating on sand production. Channel loss and permeability, and to provide a theoretical basis for on-site construction
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