Pushing the Envelope: Successful Hydraulic Fracturing for Sand Control Strategy in High Gas Rate Screenless Completions in the Jauf Reservoir, Saudi Arabia

Abstract

Abstract Hydraulic Fracturing for sand control techniques in screenless completions have been successfully attempted, predominantly in oil wells, by operators the world over; whereas, frac-packing has rapidly become the preferred option for high rate gas wells in highly permeable reservoirs. Saudi Aramco is currently undertaking one of the largest gas development projects in the world comprising a large number of new deep wells, four world-class gas plants, and massive development of new infrastructure. The Jauf reservoir, one of several forming part of the gas development project, is a sandstone with unique characteristics, because it exhibits low to moderate permeability but high sanding tendency caused by high degree of rock unconsolidation under high pressure and temperature conditions. Frac-packing was considered as a potential sand control technique early during the planning phase, but the relatively low permeability encountered upon testing of the first Jauf reservoir producers clearly indicated that highly conductive, long half-length hydraulic fractures would be required to meet gas rate project targets. Hence, the decision to pursue fracturing for sand control techniques with screenless completions techniques was made. This paper presents the results of a performance driven process, successfully implemented by Saudi Aramco in partnership with Schlumberger, which has achieved sand and solids free gas production in a score of wells treated to date. A detailed description of the combination of effective techniques applied as part of the process is provided, and lessons learned throughout the fracturing campaign are shared. The solids free gas production rates achieved in the wells discussed herein range from 10 to 50 MMSCF/D at high condensate yields. All wells were repeatedly cycled and, in some cases, limitation on the testing equipment used prevented testing wells at higher solids free rates to achieve full potential. Introduction Saudi Aramco embarked on an aggressive non-associated gas reserves development program and expansion project in 1995. This project encompasses the drilling of new wells, development of the known reserves in the Ghawar field and new fields, construction of new facilities, and upgrade and expansion of existing ones. The new Hawiyah gas treatment plant was recently commissioned with a processing capacity of 1.6 BSCFD, and the new Harad gas plant, with the same processing capacity, is scheduled for completion in mid-2003. The majority of wells drilled to feed the Hawiyah gas plant exhibited reservoir characteristics, which clearly indicated that stimulation would be required in order to meet production targets. Furthermore, core and open hole test data from the first drilled wells provided ample proof of the highly unconsolidated nature of the rock, thus giving the Jauf unique reservoir characteristics: deep, low to moderate permeability, and high sand production volumes if no appropriate control is used. The first stimulation treatment was pumped in early 1999 in a well completed with 5-1/2" tubing in 7" liner. Reservoir quality of the well is good with low Young's Modulus in several layers throughout the net sand. A two-stage fracture was pumped in this well. A 60' interval with 60° phasing was perforated for the first stage and a 20' interval for the second stage. A large pad and 20/40 ISP only were pumped at a maximum concentration of 8 ppa., so no tip screenout was desired, and no flowback control method was used. No recording of recovered solids was performed, so it is not possible to ascertain total solids recovered, but a large mass of predominantly formation sand was recovered throughout a 55 day flowback period, at which time, the well achieved a clean rate only when it was chocked back. Therefore, the treatment was rendered ineffective in controlling solids flowback.