Three Major Technological Innovations Lead to a Strategic Breakthrough for Shengli Shale Oil
2021-11-10
Recently, news of a “strategic breakthrough in shale oil exploration at Shengli Oilfield” has drawn attention both domestically and internationally. According to the report, the first batch of predicted petroleum geological reserves for Shengli Jiyang shale oil currently stands at 458 million tons, and the field now meets all the conditions necessary for comprehensive exploration and development. Oil and gas resources have always been indispensable energy commodities, crucial to both industrial development and people’s livelihoods. It is understood that shale oil refers to petroleum resources stored in the tiny pores of shale formations. As an unconventional hydrocarbon resource, its reserves rank second only to those of coal.
A reporter from Science and Technology Daily learned that the shale oil developed by Shengli Oilfield is buried at depths exceeding 3,000 meters, with temperatures surpassing 170°C and extremely high pressures. Its storage spaces are even finer than a human hair, it exhibits low maturity, high density, and poor fluidity, making its development highly challenging and posing significant technical hurdles for drilling, fracturing, and other related processes. Wang Xuejun, a senior expert at Shengli Oilfield, told the reporter from Science and Technology Daily that the strategic breakthrough achieved in Jiyang shale oil was made possible thanks to three major innovations in understanding and technological advancements:
They have innovatively developed a superior evaluation technology for shale oil, revealing the true nature of shale oil’s “hiding places.” Their rapid and efficient drilling technology, centered on synthetic-based drilling fluid systems, enables highly efficient drilling of horizontal wells that extend more than 2,000 meters in the horizontal section and are located at depths exceeding 3,300 meters underground. Moreover, their multi-scale combined fracture-network fracturing technology allows shale oil to flow along artificially created millimeter-scale “highways,” marking a breakthrough in shale oil exploration and development.
With no precedent to follow, we’ve located the “hiding place” of kilometer-deep shale oil underground.
Continental rift basins are one of the world's most important types of oil- and gas-bearing basins, characterized by unique petroleum geology features. In eastern China, including the continental interior and offshore areas, there are approximately 230 distinctive Mesozoic and Cenozoic continental rift basins, making this region the largest global concentration of continental oil- and gas-bearing basins. The Jiyang Depression serves as a prime example of such a basin.
Since the 12th Five-Year Plan, relying on the National 973 Program, major special projects, and key research projects of Sinopec, Shengli Oilfield has carried out fundamental research and technological breakthroughs on the “storage capacity, oil-bearing capacity, mobility, and fracturability” of organic-rich shale in the Jiyang Fault-Depression Basin. Significant progress has been made in geological understanding of shale oil in continental fault-depression basins as well as in related supporting technologies.
At the Exploration and Development Research Institute of Shengli Oilfield, a reporter from Science and Technology Daily saw shale oil samples extracted from depths exceeding 3,000 meters underground: a transparent glass bottle containing half a bottle of black crude oil, strikingly different from other crude oils that typically have a bright yellow hue. Compared to shale oils already developed at home and abroad, which are predominantly light oils, Shengli’s shale oil is relatively new, deeply buried, and has a lower degree of maturity, resulting in a thicker consistency. This also means that there is no international precedent for shale oils of this type, and a series of key technologies must be overcome. In April 2018, Shengli Oilfield established a shale oil project team to promote integrated geological and engineering approaches for shale oil development, fostering collaborative efforts across multiple disciplines.
They proposed, for the first time, a lithofacies classification scheme for continental shale, thereby resolving the geological prediction challenges associated with shale lithofacies in continental rift basins. They also developed experimental testing technologies for evaluating oil content in shale, clarifying the distribution patterns of free oil in continental rift basins. Furthermore, they established multi-scale characterization methods for microscopic reservoir spaces in shale and formulated a comprehensive model for the development of reservoir space assemblages, identifying key patterns of shale oil enrichment and pinpointing promising directions for future exploration. Finally, they created a series of geological evaluation and technological approaches for shale oil in continental rift basins, providing critical support for exploration and development activities and achieving a strategic breakthrough in Jiyang shale oil exploration.
During shale oil flow simulations conducted at the Key Laboratory for Shale Oil in the Shengli Oilfield, reporters observed that shale oil—saturated in nano- and micro-scale pores within the shale—can seep out through tiny fractures. Behind this apparent phenomenon lies the reservoir-space development model they have established for the Jiyang shale oil continental multi-level pore-fracture network, which has unveiled the true nature of the “hiding places” where shale oil is stored thousands of meters underground.
High-tech support paves the way and builds bridges for shale oil production.
Just recently, there’s more good news from the exploration and development of shale oil in Jiyang: Well Fan Yeping 1 has achieved a peak daily oil production of 171 tons, setting a new national record for the highest daily output from a single shale oil well. The creation of this new record wouldn’t have been possible without the support of cutting-edge technology. They’ve preliminarily developed comprehensive geological evaluation and optimization technologies for shale oil exploitation. Specifically tailored to the characteristics of Jiyang shale oil—deep burial, high temperature, high pressure, and abundant fractures—they’ve initially established a three-stage wellbore structure, oil-based drilling fluids, rotary steerable systems, PDC drill bits combined with hydraulic oscillators for accelerated drilling, and managed-pressure drilling techniques that can be widely adopted. Among these, synthetic-based drilling fluids have solved key technical challenges such as high temperatures and fluid losses, thus achieving a new breakthrough in shale oil exploration and development.
They have also, for the first time, developed a combined fracture-network fracturing technology for shale oil horizontal wells, creating an artificial, complex fracture network thousands of meters underground—effectively “building roads and bridges” to facilitate the flow of shale oil. After ten years of painstaking effort, Shengli shale oil has achieved two major strategic breakthroughs: more than 20 shale oil vertical and inclined wells, 90% of which have cumulative production exceeding 1,000 tons; and four dedicated shale oil horizontal exploration wells, each with an initial daily oil equivalent exceeding 100 tons—a high initial production rate coupled with high cumulative production. According to preliminary estimates, the total oil and gas resources in the Jiyang Depression have thus increased by more than 40%.
Kong Fanqun, Assistant to the General Manager of Sinopec Group and Executive Director and Party Secretary of Shengli Petroleum Administration Co., Ltd., as well as representative of the Oilfield Branch Company, stated that currently, Shengli Oilfield is focusing on developing longer horizontal sections and multi-layer, three-dimensional exploitation technologies. It is also innovatively applying the “well factory” model and accelerating the establishment of a national-level demonstration zone for shale oil development in the Jiyang continental rift basin. It is projected that during the 14th Five-Year Plan period, Shengli Oilfield will add 100 million tons of proven geological reserves of shale oil and build a production capacity of 1 million tons. At an oil price of $45 per barrel, this will enable economically viable development, further strengthening the country’s domestic production base and ensuring national energy security.
Source: Science and Technology Daily
Author: Wang Yanbin
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