Optimized Drilling Fluid and Tailored Drilling Practices Help Successfully Drill and Complete Wells along the Minimum Horizontal Stress Direction in Khuff Reservoirs

摘要

From a drilling operation’s prospective, wells drilled in the direction of maximum horizontal stress are ideal as they have less risk of wellbore instability. Unfortunately, when these wells are hydraulically fractured, the fracture grows along the wellbore in the direction of well azimuth. To avoid overlapping of two adjacent induced fractures and thereby communication between stages, only two to three multistage fracture treatments can be performed. To increase production and enhance recovery, operators now drill horizontal wells along the minimum horizontal stress direction to generate multiple transverse fractures during the stimulation stage. However, drilling along the minimum horizontal stress direction requires higher mud weights to minimize formation breakout due to prevailing in-situ stress conditions. This increased mud weight leads to higher differential pressures across the depleted reservoir layers, which when coupled with formation instability, creates greater challenges like stuck pipe, breakouts, and breakdowns. During the completion phase, the stiff multistage fracturing string containing multiple packers makes it more difficult to run through a slim hole, resulting in multiple failures, stuck incidents, and non-productive time. While drilling high angle wells in Saudi Arabia’s onshore gas fields, production holes are drilled through many reservoir layers. A few are highly depleted and the rest are highly pressurized. A high degree of skill is required to manage drilling fluids and drilling practices so that the depleted layers seal efficiently, thus preventing development of a thick filter cake and differential sticking incidents. This paper outlines a successful neoteric methodology adopted in these challenging wells after a detailed analysis of offset data and failure incidents. The outstanding performance achieved by adaptation in operational procedures while using the existing setup in both drilling and completion phases, challenges while implementing the strategies, and comparison of results with previous drilling techniques will also be covered in detail to help operators drilling in similar conditions.