April 1998 Vol. 219 No. 4  Production

Robert E. Snyder,  Editor

Giant field list, sand production study

A report by France's Institut Français du Pétrole (IFP) at the recent Panorama 98 conference, indicates that, during the last three years, a dozen giant oil/gas fields — defined as those with recoverable reserves of more than 500 MMboe — have been discovered throughout the world. In 1996, most new discoveries, of all sizes, were made offshore, particularly in the Gulf of Mexico and the Gulf of Guinea; this has generated "tremendous enthusiasm for the deep offshore."

In IFP's list, Australia is No. 1 with four giant fields: 1995's Chrysaor and Perseus gas fields, with 1,500 and 1,700 MMboe, respectively; 1996's Bayu / Undan gas field (1,100 MMboe); and last year's 600 – 2,700-MMboe Cornea oil discovery. Other major discoveries, by year, are as follows.

In 1995, the Florena et Pauto gas/oil field gave Colombia a 1,650 MMboe find; the Congo's Moho oil discovery was rated at 630 MMboe; and Algeria's Hassi Berkine Sud oil field added 800 MMboe. In 1996, four other countries found giant fields, including: Angola's Girassol 500 – 1,000 MMboe oil field; Brazil's Roncador oil find (750 – 1,300 MMboe); Nigeria's Bonga oil field (500 MMboe); and Norway's Smoerbukk A&B gas structures (1,820 MMboe).

Last year, Angola added the Dalia oil find, which is not yet appraised, and the 14-2X oil field with an estimated 500 – 1,000 MMboe — these two finds are not yet officially added to the IFP dozen. The U.S.'s only entry in the list was the 1997 Madden gas field in Wyoming, with 750 MMboe.

The report has a useful summary of significant discoveries in all of the world's oil/gas areas over the three-year period. It concludes that the 12 giant oil/gas finds for 1995 – 1997 are more than the seven added during the previous three years, 1992 – 1994.

In an interesting note, the wrapup says that in the U.S., two thirds of all discoveries were made in the Gulf of Mexico and Texas. And between 1995 and 1996, the number of U.S. exploration and development wells increased by 12% and 14%, respectively. The report is titled Recent oil and gas discoveries. IFP's fax number is 33 1 4752 7096.

Sand production microscopic study. In the March issue of Partnership Progress, the lead article describes research into the causes of sand production. It says, because of its adverse effect on well productivity and equipment, one of the oldest problems is production of formation sand into a well. The Near Wellbore Mechanics project — under DOE's Advanced Computational Technology Initiative (ACTI) program — was formed to gain an understanding of the contributing mechanisms occurring at the microscopic scale.

Sand production occurs when the loading on sand particles, induced by fluid flow, is greater than the formation's strength. The formation material collapses locally, and sand fragments are carried into the wellbore. This also creates cavities in the formation that increase in size and eventually become unstable, leading to wellbore collapse.

The Near Wellbore Mechanics project team is developing a code that will enable it to model a representative section of a single perforation channel next to a wellbore. The project is experimenting with the coupling of fluid and particle motion by combining a finite-element fluid flow model with Discrete Element Methods (DEM). Each grain of material is modeled as a discrete object with a geometric representation of its surface topology and a description of its physical state (position, orientation, body forces, etc.). The simulated system evolves over time by tracing the trajectory of each particle under the influence of some physical field.

Current modeling techniques utilize circular shapes to represent sand grains. DEM then depicts the motion and interaction of individual sand grains. With DEM, the team is developing techniques to efficiently represent and process particles with irregular geometries consistent with grain shape and size, to predict the conditions under which sand production will occur.

Geological models are produced using the MIMES (Modeling Interacting Multibody Engineering Systems) code to represent the pressure, sandstone strength, pressure drop, type of fluids, fluid viscosity, and sand grain-size distribution of a region. A perforation channel can then be introduced into the model to see how the well will produce. The techniques that are being developed in this project do not stop the production of sand, but enable the prediction of its occurrence.

Project companies include Sandia National Laboratories, the Massachusetts Institute of Technology, and Terralog Technologies USA, Inc. DOE Defense Programs funds this project. One contact is Sandia's project member D. S. Preece, Tel: 505 844 6259; E-mail: dspreec@sandia.gov.

Statoil prepares for "millennium bomb." On page 121, we present an article about how to prepare for the "millennium bug." Statoil notes that it, and other operators off Norway, are already taking action to protect their computer systems that have a key role in oil/gas production from what they call the "millennium bomb." This "bomb" or "bug" of course refers to the transition to Jan. 1, 2000, and potential problems with computers, and the systems they control, not being programmed to know that the two-digit date 00 means the year following 1999, not 1989. Initial tests started in May.

Statoil's core team manager, who is responsible for the company's systems on its Norwegian, Danish and Chinese projects says relevant systems are being identified with a survey of micro-processor-based hardware/software. Statoil is cooperating on what it calls the "Y2K" issue with other area operators. They meet once a month in the Y2K Oil & Gas Forum, established last summer by Statoil and Shell.

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Copyright © 1999 Gulf Publishing Company