I have been working in the petroleum industry for more than 35 years now. As I reviewed papers for this feature, I reminisced about a couple of events in my early career. First, as I was looking through petroleum journals, an article on the pending oil shortage caught my interest. The author outlined how, at current or increasing production rates, current development scenarios, and current prospective of new discoveries, oil production would soon peak. Thus, with increasing oil demand, a world oil shortage was imminent.
The Bakken Petroleum System, which includes the Bakken and Three Forks shales in North America, is estimated to hold as much as 900 billion bbl of original oil in place. However, the technically recoverable oil is a fraction of the total, estimated to be 20 billion bbl to 45 billion bbl, because most of the 8,000 producing wells have a recovery factor of about 3% to 10%. "And in fact, 10% is anomalously high," said James Sorenson, a senior researcher at the Energy & Environmental Research Center (EERC). "So it is clear with the enormous size of the prize in the ground that even small improvements in recovery could yield significant amounts of oil." Sorenson is leading a research project involving government agencies and several upstream companies in search of a way to squeeze more oil out of the Bakken for years to come by using CO2 for enhanced oil recovery (EOR).
To optimize the development plan of a giant carbonate reservoir offshore Abu Dhabi to extend the production plateau and improve recovery, detailed sector models were used to facilitate the large number of required simulation runs. The findings from those sector models were then incorporated in the full-field model (FFM). An optimized field-development plan is proposed, involving an infill drilling strategy and corresponding injection strategy. The injection strategy includes optimization of the future target reservoir pressure, to achieve the best field performance. The giant field discussed here was discovered in the 1960s.
Conventional miscible- or near-miscible-gasflood simulation often overestimates oil recovery, mostly because it does not capture a series of physical effects tending to limit interphase compositional exchanges. The authors present a new engineering solution to this problem in the near-miscible case. The principle is, while using a black-oil or an equation-of-state description, to dynamically decrease the K-value of heavy components and possibly increase the K-value of light components as the oil saturation reaches the desired residual limit. The novel approach covered in this paper relies on an in-house research reservoir simulator (IHRRS). The starting point of this work is the model activated through the VAPPARS keyword in Eclipse 100 (black-oil code) that is extended to compositional simulation.
Improving oil production from mature fields is a significant challenge because of rising recovery costs and fluctuating crude oil prices. Although large investments are made in finding new reserves, typically more than 60% of discovered oil is left behind. Thus, the use of enhanced oil recovery (EOR) technologies is necessary to bring more of this oil into production. This article describes how the use of a biological EOR technique that applied produced water for reservoir flooding in a mature field led to rapid and substantial increases in oil production. Glori Energy's Activated Environment for Recovery of Oil (AERO) technology is a biological EOR method in which customized nutrients are injected into the reservoir to activate native microbes.
Chemical enhanced-oil-recovery (EOR) methods such as polymer and alkaline/surfactant/polymer (ASP) flooding are generally not considered suitable for oil viscosities greater than 100 or 200 cp. However, this perception is changing, in particular because of field results from a number of chemical EOR pilots or full-field floods conducted in Canada in higher-viscosity oil. The aim of this paper is to review some of these projects. Canada is well-known for its heavy-oil and bitumen reserves. Most of the bitumen reserves are exploited using thermal methods, such as cyclic steam stimulation or steam-assisted gravity drainage, while heavy oil is exploited mostly using cold production methods, such as cold heavy-oil production with sand.
With the easy conventional oil in Argentina having been produced, one remaining way to find new oil in existing fields is to convert fields from primary or secondary production to secondary or tertiary production, respectively. For the Cerro Fortunoso field, the high costs required to develop the field, combined with an ambiguous log response that suggested that sand was predominantly disconnected, resulted in secondary production not being implemented. To reduce the risk, a waterflood pilot was necessary to demonstrate that waterflooding has potential and to provide water-injection and production data to constrain the history-matching process. Figure 1 shows the location of Cerro Fortunoso in Mendoza province, approximately 1200 km southeast of Buenos Aires. Most large fields in Mendoza province were exploited by waterflood decades ago.
Production from oil fields can be increased by enhanced oil recovery (EOR) techniques. Among several other EOR methods, the injection of chemicals has been studied since the 1970s. In that time, anionic polyacrylamides (PAM) have proven to be efficient viscosifiers for moderate field conditions to reduce mobility of the displacement fluid, thus increasing reservoir sweep efficiency. Surfactants mobilize oil that is trapped in formation rock pores by lowering the oil/water interfacial tension. Polymer flooding is now considered an established technology, which is applied on a commercial scale in several countries.
The plunge in well completions has exceeded the drop in the number of active drilling rigs, and operators are rethinking how they fracture wells now that oil is selling for half of what it did 6 months ago. For Mike Vincent, an independent consultant who teaches fracturing courses, it led to a change in his lesson plans. "One class I am teaching this summer is titled, 'How should we complete a well in a low-cost environment?'" he said. "We need to do things differently. There should be a different optimal design if a well is drilled when oil is USD 50/bbl versus USD 100/bbl."
Drilling the Severnaya Truba field in Aktobe, Kazakhstan, has been costly and time consuming. The mechanical lifting and falling action creates a rapid variation in weight on bit (WOB), allowing the bit's DOC to fluctuate while overcoming different stresses. These variations, along with the percussion pulse created with each stroke, led to increased rates of penetration (ROPs). Drilling with an air hammer is a technique whereby gases (typically compressed air or nitrogen) are used to operate a pneumatic hammer, to cool the drill bit, and to lift cuttings out of the wellbore. Air forced down the drillstring actuates the percussion tool, which, in turn, creates an axial percussion force directed down to a specially designed drill bit.