Optimization on Well Energy Supplement and Cluster Spacing Based Upon Fracture Controlling Fracturing Technology & Reservoir Simulation - An Ordos Basin Case Study

Abstract

Unconventional reservoir is characterized by its low permeability, insufficient reservoir energy and low production. To develop unconventional resource economically and efficiently, the industry has been spending tremendous resources to optimize completion, energy supplement and cluster spacing in stimulation technology by piloting – a trial approach. However, this approach tends to be time consuming and cost significant amount of money. As the fracturing modeling and stimulation technology advances, we question: "Can we use the fracturing modeling and reservoir simulation technologies to optimize well energy supplement and cluster spacing based upon Fracture Controlling Fracturing (FCF) technology, which is the latest concept for stimulation technology with successful applications in China's unconventional oil and gas development?", so that the industry can significantly save piloting time and money, and quickly find the optimal energy supplement method and cluster spacing corresponding to optimal completion. Based on the actual geological conditions of the horizontal well group of An83 block in Changqing oilfield in Ordos basin, we first built a 3-D geological and petrophysical model by Petrel and Eclipse softwares, and then calibrated the model with multi-stage fracturing production history data of each well. Local grid refinement and equivalent permeability simulation of fractures were used to optimize the crack system and cluster spacing parameters. FCF is a new generation hydraulic fracturing technology to move all the controllable reserves per well, and develop unconventional resources economically and efficiently by making fractures matching ‘sweet spots’ and ‘non-sweet spots’. The FCF emphasizes on making all the oil and gas movable by the hydraulic fracturing for the first time, the integration of reservoir pressurization, stimulation and production. It aims at moving all the oil and gas in place, developing unconventional oil and gas resources sustainable and profitable. The FCF has been successfully applied to the Ma56 block of Santang Lake in Tuha Oilfield of China. The average cluster spacing is 39.4 ft, and each stage has 5 clusters. The ‘fracture-controlled reserves’ was raised by optimizing well energy replenishment and cluster spacing based upon FCF technology. The total fluid volume injected is 151421.4bbl per well, and the formation energy is fully supplemented. Compared with neighboring wells, the oil production has increased by 1.7 times. With outstanding performance in production enhancement for unconventional oil and gas plays, FCF is worthy of extensive promotion.

Insight into the Methods for Improving the Utilization Efficiency of Fracturing Liquid in Unconventional Reservoirs

“…A large number of high-pressure fracturing fluids are injected into the reservoir to make the formation rock rupture, produce multilevel fractures and even connect the natural fractures, providing channels for the flow of oil and gas, greatly improve the seepage capacity of the reservoir, and increase the contact area between the reservoir and the wellbore [11,12]. At the same time, the fracturing fluid with high liquid volume and high pressure carries a lot of energy, which can supplement the formation energy [13,14]. Unconventional reservoirs have poor physical properties and lack natural energy, resulting in low productivity and rapid decline by natural depletion [15][16][17][18].…”