Abstract The irregular wellbore trajectory of open hole horizontal wells poses significant challenges to tool accessibility, especially for efficient and low-cost multistage stimulation. In this paper we will tackle these challenges by sharing our experience in combining tool-free fishbone-like fracture acidizing stimulation and detailing the methodology and performance in unlocking the potential of our reservoir with reduced capital expenditure (CAPEX). The target Sa'adi Formation in Central Iraqi exhibits complex lithology with wackestone, packstone, and chert, where vertical well acid-fracturing achieved only 83 bbl/d. The first open hole horizontal well, S-1H, was drilled in Nov. 2024, and maximize reservoir potential without secondary completion is the biggest challenge for stimulation. The solution deployed 2⅜-in coiled tubing with quad-nozzle jetting tools, creating self-propped fractures via 1. 0 m³/min sand slurry (180 m/s velocity, 2-3m radial penetration). Each stage combined: Progressive sand volumes (0. 5 to 1. 0 m³) with real-time drag monitoring to prevent sticking; 20% HCL injection (20-50 m³/stage) at maximum pump rates @ 63MPa; Centralizer-assisted CT movement. Sand jetting first established infinite-conductivity entry points (total 11 m³ quartz sand), followed by acidizing (total 727 m³ HCL) to extend dissolution beyond near-wellbore regions. Operational parameters were dynamically optimized using pressure-decline analysis between stages, achieving full 1, 200m lateral coverage without mechanical isolation. Post-treatment well testing yielded 10, 647 bbl/d—127× vertical cased-hole benchmarks. Diagnostic data confirmed: 25 distinct stimulation zones (Fiber optic logging), 2. 2m average fracture penetration (Pressure fitting), and wormhole density increase from 3/cm² to 28/cm². Fiber optic logging revealed that 23 primary fractures with high density wormholes each, creating a fishbone-like infinite conductivity zone. The operation achieved 92% success rate despite severe open hole condition, completing all stages within 39 hours—70% faster than conventional ECP methods. Total costs were reduced by 2. 0 MM versus cased-hole completion, with zero CT stuck incidents. Sustained production over 90 days demonstrated stable fracture conductivity, outperforming offset wells' 40% decline rates. This strategy delivers the industry's first tool-free fishbone fracture stimulation technology via sand jetting & acidizing in open hole wells. It provides a technical solution for the low-permeability and complex lithology carbonate reservoirs in the Middle East.
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