Well, Reservoir, and Facility Management-Guided Rigless Matrix Stimulation in a Behind-The-Sleeve Gravel Pack: Coiled Tubing and Pressure Pumping Integration Restores 137% Production in the Niger Delta

Abstract A well in the Oki-Oziengbe Field in the Niger Delta experienced a 71% production decline over 16 months due to near-wellbore damage caused by fines migration, emulsion blockage, and wettability changes. A rigless restoration approach was chosen, involving careful coordination of chemical treatments, pressure pumping, and coiled tubing operations. In line with Well, Reservoir, and Facility Management (WRFM) principles, a detailed pre-job review was conducted to assess both the stimulation opportunity and the risk of stimulating the underlying water leg rather than the oil leg, as the well was already producing at ~11% water cut. The review considered reservoir surveillance trends, completion constraints (behind sleeve with an Internal Gravel Pack), and the regional geology of the Niger Delta, with the target reservoir identified as unconsolidated sandstone prone to fines migration. Pressure Transient Analysis (PTA) confirmed a high skin factor (>53) and significant skin buildup (ΔPskin >250 psi), providing clear justification for stimulation but with careful fluid placement and diversion. A staged fluid program—comprising a proprietary microemulsion, acid system, and after-flush—was delivered through coiled tubing under strict wellhead pressure limits (≤3,000 psi). Toolstring reciprocation and displacement sequencing enhanced radial penetration and placement efficiency. Injectivity testing confirmed safe matrix rates, while pre-flush sequencing minimized the risk of incompatibility. Nitrogen lift, staged at 262-350 scfm, supported post-job cleanup and natural flow. Continuous WRFM-driven risk checks guided execution, monitoring for early water entry, and ensuring stimulation energy remained focused on the oil-bearing interval. Post-treatment results showed sustainable recovery. Production increased by 137%, while the water cut decreased from 11% to 2.5%. This case marks the first recorded chemical stimulation in a behind-the-sleeve, internal gravel-packed completion. Beyond fluid selection, this work emphasizes the importance of injectivity testing, pressure-pumping design, and coiled-tubing placement strategies for successful, rigless matrix stimulation campaigns in complex completions.