DRILLING AND COMPLETION TECHNOLOGY

Horizontal well completions often show uneven production along their length due to fractures and heterogeneous permeability and saturation. Once the problem areas were identified by production logging, the novel use of inflow control devices and flow equalizers resulted in substantial improvement in recovery. This new completion technology lowered water production and improved ultimate recovery in two wells in the United Arab Emirates, as told by authors from ADCO and Baker Oil Tools.

Hydraulic horsepower is very important in conventional drilling, helping bits perform at optimal levels. The energy can be put to more efficient use by accelerating high-density particles through the nozzles of the drill bit, using particle impact drilling as the primary cutting mechanism. Authors from Particle Drilling Technologies explain how it is done and update us on recent developments.

While drilling an extended reach well in the North Sea, the operator needed to build angle from 52 to 75 degrees while drilling near 6,000 ft to over 20,000 ft through sticky formations. The operator chose to use a casing-while-drilling system. Authors from Weatherford explain how casing-while-drilling saved seven days of NPT, usually required for running casing on wells in this field.

Poor long-term performance of fibers, especially at elevated temperatures, is still a problem. This issue is critically important using Distributed Temperature Sensing (DTS) in Steam-Assisted Gravity Drainage (SAGD) applications, where wells operate at very high temperatures, often exceeding 250°C, high pressures and a hydrogen-rich environment. Authors from WellDynamics and Japan Canada Oil Sands Limited (JACOS) present results from the first full-scale field trial of a new single-mode DTS system designed for long-term reliability in these harsh conditions.

Swellable rubber. It’s been known for many decades that rubber tends to swell when exposed to oil and gas. Nearly 10 years ago, two companies began working on commercial aspects that exploit this property. Now that the rubber types are known, and testing concluded, the technology is moving into the marketplace. Shell Global Solutions’ version, called Swellfix, has completed many jobs using the technology for isolation with packers, zones and other uses. Examples tell the story.

Shallow gas-charged sands present a significant drilling risk in the Erha field offshore Nigeria. ExxonMobil evaluated the potential for subsea gas blowouts in its drilling plan through the riserless-conductor hole interval. This method, which resulted from modeling shallow-gas flows, includes dynamic kill operations to prevent and mitigate these flows.

Authors from Saudi Aramco and Halliburton discuss the effectiveness of a new slickline-deployed electro-mechanical tubing punch that resolved problems arising from the use of conventional mechanical perforating tools. Field studies of the new tool’s application in the operator’s wells demonstrated operational advantages and a significant impact on safety and economics.

 ENHANCED OIL RECOVERY

Microbiological enhanced oil production. Authors from the Russian Academy of Sciences, Dangang Oilfield Co., Yangtze University and Petrochina Co. Ltd. discuss microbiological technology for EOR based on the activation of the stratal microflora that was tested in the high-temperature horizons of the Kongdian bed (60°C) of the Dagang oil field, China. This biotechnology consists of pumping a water-air mixture, and nitrogen and phosphorus salts into the oil stratum through injection wells to stimulate the activity of the stratal microflora, which produce oil-releasing metabolites. Watercut decreased and the oil content increased, recovering more than 98,000 barrels of additional oil over 3.5 years.

 PRODUCED WATER REPORT

Downhole sand protection. Field tests in southwestern Saskatchewan, Canada, demonstrated the effectiveness of a downhole desander to protect electric submersible pumps from failure. Husky Energy Inc. wanted to reduce operating costs, 24% being attributed to well workovers and related servicing costs. The downhole desander, supplied by Enerscope Systems Inc., employs centrifugal action to separate the heavier-than-water particles from the water stream. The tool has no moving parts, no screens or filter elements to clean or replace, and requires no backwashing. It allowed the ESP to have a significantly longer run time and better overall efficiency than any previous pump placed in that particular well. Also, fluid pumping rates were higher than expected.

 EXPLORATION

Wide, wider, and in between, what does WAZ, MAZ, RAZ all mean? And what are the cost issues involved with these seismic acquisition methods? When is it justified to use one of these methods? Will all subsalt plays end up using one of them? And what else, besides subsalt, are these seismic acquisition methods best used for? These and many other questions are answered in this important report from World Oil.

Seismic characterization of giant sand injectites in the North Sea and West of Shetland: Reservoirs, conduits and drilling hazards. Author from the University of Aberdeen discusses the properties of sand injectites and their potential to provide highly permeable reservoirs and pathways for fluid migration through otherwise poorly permeable shale intervals. The author also argues that sand injectites may constitute drilling hazards when using high-pressure/heavy muds to drill through polygonal-faulted mudstones.

 DRILLING, COMPLETION AND WORKOVER FLUIDS

World Oil’s ever-popular, exclusive annual reference comprises about 25 pages that show trade names, generic descriptions, recommended usage and suppliers of nearly 2,400 fluid systems/additives for drilling, completion and workover.