Open-hole gravel packing in vertical/conventional wells is an accepted sand exclusion method that has not gained wide and rapid application in horizontal wells. The reason is largely due to sand placement challenges in the horizontal drain that could lead to premature sand screen-out. Consequently, many operators are skeptical gravel packing horizontal wells since failure could probably result in enormous capital risk. In the Niger Delta, about 70 % of the hydrocarbon-bearing reserves lie in shallow unconsolidated reservoirs where the sonic transit time vary between 110 to 140 us/ft. Production from these intervals has proven record of sand threats to operating cost, well integrity, surface facilities and production sustenance. The challenge is to complete wells in these reservoirs with sand exclusion materials that would guarantee full life-cycle production performance. Early horizontal wells in the region were completed with stand-alone screens, but recently, the expandable sand screen (ESS) took a leading edge. Though the ESS has a higher inflow area compared to other screens, its high cost, lack of full-bore expansion and the required lead-time continue to raise concerns especially when considered for applications in brown field development where well potential and reserve rewards are low. In response to these concerns, in 2002, openhole gravel packing (OHGP) in a horizontal well was investigated and considered as an alternative sand exclusion option in Shell Petroleum Development Company (SPDC). The trial candidate, the Obigbo-North QWSB-3 was selected and successfully completed as the first horizontal OHGP in SPDC using the alpha-beta wave concept. Based on simulation results, about 9237 lbm of sand was planned for placement in 1000-ft of 6.0-in hole size, however, the actual sand pumped was about 10830 lbm. This represents an estimate of 6.25-in drain hole size. The application saved over $0.3 million when compared to the cost of using ESS. For the Eastern asset team that drills an average of 12 wells annually, an annual projected completion cost-saving of some $3.6 million is achievable. Based on the initial production testing, Obigbo-North Well QWSB-3 tested 3250 BOPD with a productivity index (PI) of 130 bbl/(psi-D). Baseline Memory Production Logging Tool (MPLT) logging showed that the entire drain section completed on the clean sand member had effective inflow into the linerbore. In addition to establishing confidence in the application and performance efficacy of OHGP, this trial and the significant cost-savings will engender a paradigm shift to horizontal well sand control. In this presentation, we will share some data and results based on field experiences, challenges and new understanding. Introduction This paper discusses the first application of horizontal open hole gravel packing as a sand control method in SPDC. The paper further demonstrates the evaluation of the inflow profile (based on memory production log) as a yardstick for determining the completion efficiency, and reveals the economic argument against using ESS as seen in Well QWSB-3 (figure-1) located in the Obigbo-North field of Niger Delta, Nigeria (figure-2). Production "hot-spot-effects" a phenomenon characterized by massive inflow into the liner-bore at a particular point (figures-3–5) is a common phenomenon in horizontal wells completed with stand-alone screens and ESS (that are not fully expanded to the sand-face). The problem is attributed to differential plugging of the completion screen by the migrating formation fines and/or improper horizontal drain section clean out2,3,4. When a stand-alone screen is partially plugged, the resultant annular flow converges to a point where intense inflow into the liner-bore is observed. This problem leads to higher drawdown, liner erosion, sand failure and ultimately production decline1,10. These problems commonly associated with wells completed with stand-alone screens, led to the many recent applications of ESS by the SPDC Land Asset Team. However, high material installation cost and complete expansion remain key challenges in ESS applications. SPDC decided to try horizontal OHGP as an alternative sand exclusion option that will be cost-effective and capable of sustaining production. Consequently, a trial application was executed at the end of the second quarter of 2002 in Obigbo-North Well QWSB-3. The well was planned to develop some 8.5 Million STB from the D3.200A reservoir at an initial offtake rate of 3000 BOPD (tables-1,2).

TX 75083-3836, U.S.A., fax 01-972-952-9435. AbstractA 360-degree rotating jetting tool has been successfully deployed to cleanup about 1000 ft of 6.25" horizontal openhole gravel packed (OHGP) well. The exercise was carried out using Nitrified 10% HCl placed from the toe to the heel at Coil Tubing average rate of 20 ft/min. Three passes were made at total fluids rate of 1.0 bpm. During the fluid placement, no losses were encountered. After the treatment and initial production testing, a baseline memory production log (MPLT) was acquired across the horizontal drain section to evaluate the completion/cleanup efficiency. The MPLT results indicated a better drain hole cleanup as seen in the inflow profile of the completed drain section. Higher contribution was also noticeable in the cleaner sand members. From the result obtained, the 360-degree rotating jetting tool can be efficiently applied to cleanup drain holes especially in horizontal wells equipped with gravel packs.

We describe the application of a high hydraulic horsepower jetting system to deliver treating fluids in horizontal wells drilled in high permeability formations to improve their performance. This high hydraulic horsepower jetting system was originally developed to remove scale from tubulars. The same system with some minor modifications can be used to deliver treating fluids with high energy at downhole conditions therefore reducing the overall amount of treatment fluid for some specific applications. On newly drilled wells this means less rig time to perform the post completion cleanup. Two case histories are presented where a newly drilled horizontal well was treated successfully with less than half of the volume typically required for such application. The same jetting system can be used to perform regular cleaning operations of horizontal wells with inexpensive fluids reducing also the overall treating fluid volumes thus generating an additional saving on pumping time and logistics. Application of this jetting system in horizontal producers has evidenced that produced gas and water rates can be reduced with such cleanup treatments. Five horizontal well cleaning case histories are presented. The system can also be used in conjunction with a simple fluid tailored to treat a well specific problem such as unplugging sand control screens from drilling and formation fines. Again with the use of the high hydraulic horsepower jetting system the use of chemical products that require special handling or have a high cost can be minimized. A case history is described and includes pretreatment and post treatment production logs. Finally two applications of this high hydraulic horsepower jetting system to remove bacterial growth from deviated gravel packed injection wells are also presented. Introduction With the development of drilling technology more and more wells are drilled horizontally. A horizontal wellbore allows exposing a relatively large reservoir area for a more effective drainage of hydrocarbons or injection of fluids for pressure maintenance. The horizontal wells here analyzed are completed with slotted or predrilled liner without External Casing Packers. Horizontal lengths can extend up to 3000 ft. Treatments that are typically performed on these wells are post completion filter cake removal and matrix stimulation. Considering the length of these horizontal sections these treatments have different significant impacts:first is an economic related to cost of products and to the rig time required to perform such treatments. Another impact is the associated cost of transportation of equipment and materials to the well site.there can be a significant logistic impact when all equipment and materials need to be placed on small production platforms or on small offshore rigs. Even land operations can significantly be affected from such operations as the number of shipments to a certain location might exceed the capacity of certain segments of the local transportation network.there is also a potential impact on the environment as with large quantities of chemical products involved the probability of a spillage are higher.