A thread running through conflicts in the Niger Delta is the struggle for oil rent ownership and access. This paper explores the dynamic and contested processes through which informal access to crude oil and its associated rents is negotiated in the Niger Delta. It contends that in the informal oil economy, access to oil and related rents is fluid, changing as a result mutable social and power relations. Informal access is shaped by the local power dynamics, and are shaped by linkage to industry actors and state-capture networks. The study is qualitative and historical, and it draws from political ecology and access theory to operationalise how informal practices and state-capture actors collaborate to undermine formal legal frameworks of resource governance. It shows how informal access is necessitated by exclusionary regulatory regime, and mediated through complex local power structures, fluid network linkages, and transnational relationships of patronage, which connect the community, subnational and federal levels. The analysis also reveals the link between structural and symbolic aspects of access, and how narratives of dispossession, resistance and survival, alongside symbolic displays of resistance, help legitimise informal appropriation morally and ideologically, while at the same time concealing its hierarchical nature. The conclusion reached is that the mutability of access arrangements is the primary driver of the informal oil economy's resilience and persistence, and that policy responses premised on static conceptions of access are structurally inadequate to address it. The paper, thus, recommends that policy interventions target root causes of the turn to informal economy such as legal dispossession, revenue exclusion, environmental destruction, and the failure to translate oil wealth into local development. This will mark a shift from symptom-focused interventions that target informal economic operations, which in turn, mutate and continue to survive.