Feb. 1, 2003
A new water management technology features a relative permeability modifier (RPM) that selectively blocks water flow to the well without blocking oil or gas.

Water management

A new water management technology features a relative permeability modifier (RPM) that selectively blocks water flow to the well without blocking oil or gas. AquaCon RPM technology was developed by BJ Services to offer the oil industry a more effective way to reduce water while potentially boosting relative oil and gas production.

RPMs are generally high-molecular-weight polymers with components that have an affinity for both rock surfaces and formation water. By partitioning themselves between the rock and the aqueous phase of the formation, they limit water inflow through the pay zone to the wellbore. The new RPM technology has already helped to shift the traditional focus on decreasing formation permeability and controlling undesirable water to strategies for hydrocarbon enhancement.

This technology was implemented in the Far East, West Africa, the United States, and South America with encouraging results. For example, in Ecuador, the technology was used to reduce water flow and boost relative oil production in a 206°F well. A moderate molecular-weight polymer forms the basis for the technology. The polymer attaches itself to the rock matrix, selectively plugging the water phase of the reservoir. For this application, a team of chemists and engineers in Ecuador conducted core flow tests and designed a system to meet the objective. Additional laboratory test data was provided to support a final treatment design. Oil production increased by 50%, from 333 to 501 b/d while reducing water cut of about 85% to less than 65%.

AquaCon is a moderate molecular weight hydrophilic terpolymer based on polyacrylamide. The polymer is also composed of sulfonated moieties that enable the polymer to better tolerate brine fluids, especially those containing divalent cations. This characteristic, coupled with a unique chemical structure that allows the polymer to attach itself to rock, provides the basis for the polymer's performance.

Click here to enlarge image

A relative permeability modifier can selectively block water flow to the well without blocking oil or gas.

For matrix applications, the treatment candidates include wells that produce water from a zone separate or distinct from oil or gas production zones. Treatment can be bullheaded or pumped through coiled tubing, without the need for mechanical zone isolation. For those requiring an acidizing application, this specialized technology may be added to acid diverter stages or used as a pre-treatment to sandstone acidizing in oil or gas wells where water production is anticipated from a bottom zone or lower portion of the hydrocarbon-producing zone.

Finally, for fracturing applications, this technology is compatible with, and can be added to, the water-based fracturing fluids to reduce post-stimulation water production, and increase fracturing fluid efficiency through reduced leak-off, thereby increasing effective fracture length and conductivity. It may be included in pre-pad and pad stages, and may be also be pumped as a post-fracturing treatment following load recovery.

Expandable tubular

The 100th solid expandable tubular system has been installed in an El Paso Production well in the East Cameron area in the Gulf of Mexico by Enventure Global Technology. Currently, the expandable tubular system is installed in major oil basins worldwide and is becoming an integral part of well plans for more than 35 operators in the oil and gas industry.

The 401-ft openhole liner system, installed in a well in the East Cameron field, was expanded in 9 5/8-in. 53.50-ppf base casing. Combined mechanical and hydraulic forces, averaging 150,000 lb and 3,600 psi, respectively, expanded the pipe by 11.6%. Post-expansion ID of the 7 5/8-in. 29.70-ppf liner was 7.674 in. (compared to a pre-expansion diameter of 6.875 in.), while post-expansion burst and collapse were estimated at 5,990 psi and 2,700 psi, respectively. Overall liner length was reduced from 401 ft to 385 ft as a natural result of the expansion process.

To date, 106 installations have been performed by expanding more than 105,000 ft of pipe and 2,700 connections for 35 operators globally.

Real-time tool

A new magnetic resonance (MR) logging-while-drilling tool delivers real-time producibility information needed for steering decisions to enhance well performance. Schlumberger Oilfield Services recently announced the introduction of the Provision real-time reservoir steering tool.

Field tested under a wide variety of conditions worldwide, the tool has an extensive track record including 49 MR LWD runs for 13 different operators in 35 wells, with footage logged-while-drilling now exceeding 100,000 ft.

Obtaining the magnetic resonance data during drilling allows the drilling process to be optimized to increase well performance. The tool has been delivering reliable real-time data transmission of LWD productivity data since mid-2000 to support the need for real-time decision-making that improves overall project economics.

Designed and tested to full LWD shock, temperature, and pressure standards, the tool does not require radioactive sources and is fully compatible with existing technology. The tool can be placed anywhere in the bottomhole assembly (BHA), including directly above the bit, and still provide real-time data transmission. Downhole motion data can be used to optimize drilling parameters and actually increase the lifetime of the BHA for further rig time and cost savings.

Real-time data transmission can reduce drilling cost by delivering information for early sidetrack, plug and abandon, and completion decisions, as well as provide information to optimize completion designs and increase knowledge of reservoir productivity.

Risks associated with drilling unnecessarily long intervals and under performing wells may be avoided. Logging-while-drilling MR is the only option in extended reach horizontal wells that require pipe rotation to reach the bottomhole section. The tool also addresses situations of poor borehole stability and demanding deepwater conditions.

Expandable sand screen

The Completion Systems Division (WCS) of Weatherford International Ltd. has completed installation of 5-1/2 in. expandable sand screens (ESS), complete with enhanced connectors, in five wells for Phillips China Inc., a subsidiary of CononcoPhillips, off Bohai Bay in Northern China.

Phase 1 of the ConocoPhillip's PL 19-3 operations in Bohai Bay consists of 24 wells that provided a series of challenges due to a complicated subsurface environment. The nature of the generally weak reservoir rock, much of it unconsolidated, means there can be severe sand control problems. This enhanced ESS 5 1/2-in. connector is quick to install, and offers increased strength and reliability.

The first ESS installation was well A-6, a 9 5/8-in., cased hole perforated 40° incline, running to a depth of 1750 m, with 21 ESS joints. ESS has also been installed in three other cased hole wells – A-5, A-12, A-23 – and in A-18, an open-hole deviated well. A total of 104 ESS joints have been run to date. Phillips China Inc. operates the PL 19-3 Field, with a 49% interest. Cnooc China Ltd. own 51%.