First Successful Proppant Fracture for Unconventional Carbonate Source Rock in Saudi Arabia

Abstract

Widely recognized as the world leader in crude oil production, Saudi Aramco has only recently begun to explore for unconventional gas resources. Saudi Aramco started evaluating its unconventional reservoirs to meet the anticipated future demands for natural gas. One of the subject plays that is currently being evaluated is a carbonate source rock with nanodarcy permeability and very low porosity. The target formation has few, if any, analogs that can be used for comparison. Knowledge of the formation characteristics, geomechanics, stimulation response and production potential has been nonexistent until recently. Historically, all attempts to hydraulically fracture stimulate carbonate formations in Kingdom have resulted in premature screen-outs. This paper will discuss the hydraulic fracturing stimulation design, execution and evaluation of the first successful proppant fracturing treatment in an unconventional carbonate source rock in Saudi Arabia. The successful two-stage treatment proved that proppant fracturing techniques could be utilized to stimulate carbonate formations after modifying the stimulation design, specifically the perforation strategy, fracturing fluids and proppant type. The Tuwaiq Mountain and Jubailah formations were treated with 104,000 lbs and 114,956 lbs of proppant respectively. INTRODUCTION Saudi Aramco's unconventional gas exploration efforts were influenced by the growing local gas demand and the economic success of shale exploration in the United States, Canada, Europe and Australia. Saudi Aramco started evaluating its unconventional reservoirs and their potential to reduce oil consumption in the electricity sector and to fuel the anticipated future demands for natural gas. "The multi-stage fracturing technique has facilitated the development of shale gas and light tight oil production in the United States and is believed to do so in the other countries with unconventional hydrocarbon resources" (1). Saudi Aramco has embarked on an unconventional exploration and appraisal project to assess its unconventional resources potential in three geographic areas, Northwest, South Ghawar and East Ghawar. Hydraulic fracturing techniques will be utilized to enhance production by connecting natural fissures and creating high connectivity pathways for gas to flow into the well.

Workflow for Probabilistic Resource Estimation: Jafurah Basin Case Study (Saudi Arabia)

“…Stimulations in early horizontal wells were designed with 16 stages per lateral, each stage with three 1.5-ft clusters [41]. Central Jafurah wells have a true vertical depth (TVD) of around 10,000 ft and lateral lengths exceed 5000 ft [28,41].…”

“…Stimulations in early horizontal wells were designed with 16 stages per lateral, each stage with three 1.5-ft clusters [41]. Central Jafurah wells have a true vertical depth (TVD) of around 10,000 ft and lateral lengths exceed 5000 ft [28,41]. The low clay content of the Tuwaiq Mountain Formation of Jafurah Basin leads to both increased fracability (high brittleness) and reduced risk of clay swelling during and after completion.…”

“…However, the treating pressure needed for wells is higher (around 0.98 psi/ft-1.05 psi/ft) [42]. The significant amount of condensate produced during testing of horizontal wells [41] draws attention due to possible risks of condensate banking and possible liquid loading in the wellbores. The wells are drilled in NW-SE direction to align with the least principal stress of a strike-slip regime that can be readily inferred from the regional tectonics [22].…”