Hydraulic Fracturing Case Histories in the Carbonate and Sandstone Reservoirs of Khuff and Pre-Khuff Formations, Ghawar Field, Saudi Arabia

摘要

As part of gas production enhancement and quick recovery ofrnreserves initiative, hydraulic fracturing campaign was initiatedrnin 1998 to treat the sandstone and carbonate formations in thernGhawar gas fields in Saudi Arabia. To date, numerous wellsrnhave been matrix acidized, acid fractured, and proppantrnfractured. Many different procedures and fracturingrntechniques have been adopted as part of learning process tornoptimize candidate selection, perforation strategy, fracturerndesign, and implementation.1,2 The incremental productionrnfrom the Khuff carbonate gas ascertains the success of the acidrnfracturing treatments.3 For the Pre-Khuff sandstone reservoirs,rnbecause of the unconsolidated nature of some high potentialrnsandstone layers, indirect fracturing technique has beenrnadopted where the consolidated, low porosity section isrnperforated and from where the induced fracture is initiated.4rnThis procedure curtails the risk of sand production. Veryrnrecently, fracturing wells with frac&pack technique andrncompleting them with mechanical screen are beingrnimplemented. Successes on these Pre-Khuff treatments arernusually judged by sand free production rate and conditions andrnby comparing post-fracture production increase withrnsimulated, pre-fracture production based on reservoirrnproperties calibrated by post-fracture production match. Inrnmost cases this gain is significant to justify the expenses of thernfracture treatment. However, the priority in Saudi Aramco isrnto recover the required volume of gas to feed its giant gasrnplants. This paper presents field cases from the carbonate andrnsandstone reservoirs treated with acid and proppant,rnrespectively and provides a general picture of how all thernfracture treatments are currently being conducted.