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Interwell tracer tests are widely used. This article reviews some of the studies reported in open literature. The selection introduces different problems that have been addressed, but the original papers should be studied to obtain a more detailed description of the programs. The Snorre field is a giant oil reservoir (sandstone) in the Norwegian sector of the North Sea. Injection water and gas were monitored with tracers, 18 and the resulting tracer measurements are discussed in this page.
Well-to-well tracer tests contribute significantly to the reservoir description, which is essential in determining the best choice of production strategy. Direct dynamic information from a reservoir may be obtained, in principle, from three sources: production history, pressure testing, and tracer testing. The value and importance of tracer tests are broadly recognized. Tracer testing has become a mature technology, and improved knowledge about tracer behavior in the reservoir, improved tracer analysis, and reduction of pitfalls have made tracer tests reliable. Many tracer compounds exist; however, the number of suitable compounds for well-to-well tracers is reduced considerably because of the harsh environment that exists in many reservoirs and the long testing period. Radioactive tracers with a half-life of less than one year are mentioned only briefly in this chapter because of their limited applicability in long-term tests. Tracers may be roughly classified as passive or active. In principle, a passive tracer blindly follows the fluid phase in which it is injected. Interpretation of tracer-production curves must account for this. The results from the application of active tracers may give information about fluid saturation and rock surface properties. This information is especially important when enhanced-oil-recovery techniques that use expensive fluids such as surfactants, micellar fluids, or polymers are considered. In the last 50 years, many tracer studies have been reported and even more have been carried out without being published in the open literature. Wagner pointed out six areas in which tracers could be used as a tool to improve the reservoir description. Many companies apply tracer on a routine basis. The reservoir engineer's problem generally is a lack of adequate information about fluid flow in the reservoir. The information obtained from tracer tests is unique, and tracer tests are a relatively cheap method to obtain this information. The information is an addendum to the general field production history and is used to reduce uncertainties in the reservoir model. Tracer tests provide tracer-response curves that may be evaluated further to obtain relevant additional information. Primarily, the information gained from tracer testing is obtained simply by observing breakthrough and interwell communication.
Conventional well completions in soft formations (the compressive strength is less than 1,000 psi) commonly produce formation sand or fines with fluids. These formations are usually geologically young (Tertiary age) and shallow, and they have little or no natural cementation. "Friable" and "Unconsolidated" are two commonly used terms to describe the nature of the reservoir material. Sand production can plug tubing, casing, flowlines and surface vessels. It can erode equipment that leads to loss of well control or unwanted fluid emissions.
Steam assisted gravity drainage (SAGD) is an outstanding example of a steam injection process devised for exploitation of heavy oil or bitumen reservoirs utilizing horizontal wells. It is widely used in Alberta Canada, Russia, and China for recovery of heavy and extra-heavy oilsands resources. Several variations of the basic process have been developed, and are being tested. The original SAGD process, as developed by Butler, McNab, and Lo in 1979, utilizes two parallel horizontal wells in a vertical plane: the injector being the upper well and the producer the lower well (Figure 1, taken from Butler). If the oil/bitumen mobility is initially very low, steam is circulated in both wells for conduction heating of the oil around the wells.
A ruling by Mexico's Energy Secretariat, or SENER, this month has made the national oil company Pemex the operator of the contested Zama field that was discovered by Houston-based Talos Energy in 2017. The companies have been in dispute over the shallow-water Zama prospect since 2018 after Pemex claimed that the discovery was a contiguous reservoir that extends into its offshore block. Independent reserves audits commissioned by each company have supported their own claims, with Talos' audit showing that 60% of the reservoir's estimated 670 million BOE fell within its block. Pemex estimates that its block represents 50.4% of the Zama reservoir. In statement issued 5 July, Talos lamented the decision and highlighted that it has drilled four wells in the Zama field (one exploratory, three delineation wells) and has demonstrated to Mexican authorities its ability to operate the unit.
Introduction Heavy oil is defined as liquid petroleum of less than 20 API gravity or more than 200 cp viscosity at reservoir conditions. No explicit differentiation is made between heavy oil and oil sands (tar sands), although the criteria of less than 12 API gravity and greater than 10,000 cp are sometimes used to define oil sands. The oil in oil sands is an immobile fluid under existing reservoir conditions, and heavy oils are somewhat mobile fluids under naturally existing pressure gradients. Unconsolidated sandstones (UCSS) are sandstones (or sands) that possess no true tensile strength arising from grain-to-grain mineral cementation. Before 1985, heavy-oil production was based largely on thermal stimulation, ΔT, to reduce viscosity and large pressure drops, Δp, to induce flow. Projects used cyclic steam stimulation (huff'n' puff), steam flooding, wet or dry combustion with air or oxygen injection, or combinations of these methods.
In-situ combustion is the oldest thermal recovery technique. It has been used for more than nine decades with many economically successful projects. In-situ combustion is regarded as a high-risk process by many, primarily because of the many failures of early field tests. In-situ combustion (ISC) is a displacement process in which an oxygen-containing gas is injected into a reservoir where it reacts with crude oil to create a high-temperature combustion zone that generates combustion gases and creates a heated front that propagates through the reservoir. In-situ combustion (ISC) is an Enhanced oil recovery process for heavy oil in which an oxygen-containing gas is injected into a reservoir where it reacts with crude oil to create a high-temperature combustion zone that generates combustion gases and creates a heated front that propagates through the reservoir. The most common fluid injected is air but there are some cases in which oxygen enriched gas or air is injected. In situ combustion (ISC) is applied as one of the oldest methods of enhanced oil recovery process in petroleum industry. Heavy oil is suppressed in naturally fractured reservoirs in many places around the world and might possibly provide to the world's energy supply.
Calgary-based Tourmaline Oil Corp. announced today that it is acquiring Black Swan Energy in an all-stock deal valued at CAD $1.1 billion. The transaction is set to boost Tourmaline's output by 50,000 BOE/D and the company expects to average around 500,000 BOE/D by mid-2022. The operator said the Black Swan acquisition is one of several it has made recently to become the largest producer in the north Montney Shale area of British Columbia. Black Swan's 231,000-acre position gives Tourmaline an estimated 1,600 horizontal drilling locations and proven and probable reserves of 491.9 million BOE. Tourmaline said in its announcement that Black Swan has not booked material reserves in other areas that it sees as having high potential and complementary to its existing footprint.
Pembina Pipeline will acquire a 50% stake in the proposed $2.4-billion Cedar LNG Project to develop the floating LNG facility in British Columbia in partnership with indigenous group, the Haisla Nation. The pipeline operator expects to invest about $90 million into Cedar LNG over the next 24 months, including costs to acquire its interest in the project as well as development costs prior to the final investment decision expected sometime in 2023. The company, which will acquire the equity interests in Cedar LNG from PTE Cedar LP and Delfin Midstream Inc., will operate the project going forward. Haisla will own the remaining 50% stake. Pembina has been busy of late.
This issue marks the debut of the Hydraulic Fracturing Operations feature in JPT. While hydraulic fracturing has long been a feature topic, this year, we are branching this major area of interest into both this feature and a Hydraulic Fracturing Modeling feature, which will appear in the November issue of the magazine. For this issue, reviewer Nabila Lazreq of ADNOC has selected three papers that reflect industry efforts to achieve new goals in production and sustainability. Paper 201450 investigates the potential of natural gas (NG) foam fracturing fluid to reduce the major water requirements seen in stimulation. The authors write that such requirements can be reduced up to 80% in some cases by the use of NG foams.