Waterfloods in California operate under the US Environmental Protection Agency’s Class II underground injection control regulations, which are tasked with the protection of underground sources of drinking water (USDW) within the state. A key aspect of this regulatory framework is the operation of water injection wells under a maximum allowable surface pressure (MASP) to ensure that injected water does not induce and/or extend formation fractures that could create a potential conduit connecting the hydrocarbon zone with identified USDWs. Determination of the MASP for individual injection wells has typically been calculated using a step rate test (SRT), but this method has been shown to be inappropriate for multilayered, unconsolidated sandstone reservoirs (Ershaghi and Ershaghi 2018), which are prevalent in Wilmington Field. To avoid the potential for misinterpretation of SRTs to imply fracturing in this context, in this paper we summarize the evidence demonstrating both the effective geologic containment of injected fluid in the hydrocarbon-bearing zones and the absence of injection-induced fracturing. In addition, a series of field tests were conducted to assess the stress sensitivity of the Wilmington reservoirs and investigate in-situ changes in the reservoir at higher injection pressures by combining multirate injection tests with injection profile surveys. These results provide data supporting the noted challenges associated with MASP determination for multilayered, unconsolidated reservoirs. In this paper, we give operators and regulators working in these types of fields a framework for assessing both injection containment and injection-induced fracturing that account for the unique properties of these formations.

加利福尼亚的注水井是根据美国环境保护局的II级地下注入控制法规运行的，该法规的任务是保护该州的地下饮用水源（USDW）。该监管框架的关键方面是注水井在最大允许表面压力（MASP）下的运行，以确保注入的水不会引起和/或扩展地层裂缝，而这可能会形成潜在的管道，将油气区与已识别的USDW相连。 。通常使用步进率测试（SRT）计算单个注入井的MASP，但事实证明该方法不适用于在威尔明顿油田普遍存在的多层，非固结砂岩储层（Ershaghi和Ershaghi 2018）。为了避免在这种情况下对SRT的误解以暗示裂缝的可能性，在本文中，我们总结了证据，这些证据既表明了含烃区中注入流体的有效地质围堵，又没有注入引起的裂缝。此外，还进行了一系列现场测试，通过将多速率注入测试与注入剖面调查相结合，评估了威明顿油藏的应力敏感性，并研究了在较高注入压力下油藏的原位变化。这些结果提供的数据支持与多层，非固结油藏的MASP测定相关的已指出的挑战。在本文中，