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Collaborating Authors
Case History in Achieving High Rate Producers in Sub Sea Gravel Packed Completions
Myers, Larry G. (Mobil Equatorial Guinea, Inc.) | Humphreys, Neil (Mobil Equatorial Guinea, Inc.) | Kaminski, Henry P. (Mobil Equatorial Guinea, Inc.) | Bouwaked, Elias (Mobil Technology Center) | Robertson, David (Mobil Technology Center)
Abstract The Zafiro Field, offshore Equatorial Guinea, was developed as a fast track project with production coming onstream in August, 1996 to an FPSO, less than two years from the field discovery. Downhole gauges with surface readout on the FPSO gave continual monitoring of well performance during early production from the field. These subsea wells, which required sand control, were targeted to produce at rates of 8000 bopd. Early wells made this target with Productivity Indices (PI's) of 6 to 33 bopd/psi. However the data also showed high post completion skin damage when compared to skins measured immediately after TCP operations. This real time data allowed continual improvements to be made in completion designs. This paper is a case history of these design changes which more than doubled PI's, yielding producers capable of 14,000 bopd. Design changes included a move to openhole completions where possible, new screen configurations, fluid studies for optimizing gelled fluids to transport sand in high angle and horizontal openhole completions, filter cake removal in openhole completions, and acid stimulation. P. 159
- Europe > Norway > Norwegian Sea > Halten Terrace > Block 6507/8 > Heidrun Field > ร re Formation (0.99)
- Europe > Norway > Norwegian Sea > Halten Terrace > Block 6507/8 > Heidrun Field > Tilje Formation (0.99)
- Europe > Norway > Norwegian Sea > Halten Terrace > Block 6507/8 > Heidrun Field > Ile Formation (0.99)
- (6 more...)
Formation damage usually is attributable to fluid systems that contain clay or significant amounts of water. Field experience, as well as laboratory studies, indicates that this damage can be avoided through the use of an oil-asphalt fluid system for drilling, completing, and gravel packing. Introduction The technology of sand control by gravel packing has been significantly advanced since its inception almost a century ago. This advancement has been primarily in completion design and placement techniques. Nonetheless, the success ratio of the gravel pack treatments is still far from ideal, as evidenced by well failures in many parts of the world. For example, according to a survey in offshore Louisiana, about 22 percent of the wells are production deficient and 23 percent are off production. Also, in the same area, there are over 30 workover rigs being used primarily for repair of sand control measures. It is apparent that future advancements in sand control technology will come from study and improvements of the entire drilling, completion and production system. These advancements should bring substantial rewards to the operator. When we view the over-all system, we find that for controlling formation sand a fundamental requisite is the prevention of disturbance and rearrangement and the prevention of formation productivity damage during the drilling, completion productivity damage during the drilling, completion and production operations. This is borne out by the fact that the failure of sand control measures can invariably be traced to movement of formation particles up to, into, or through the formation restraining media. To prevent movement of these formation particles, considerable effort justifiably has been applied to precise placement of sand control measures. Unfortunately, placement of sand control measures. Unfortunately, well failure may already have been precipitated by other facets of the drilling and completion process. Thus, we need to identify these damage mechanisms and their physicochemical, capillarity and elasticity relationships in order to improve sand control. Damage Mechanisms Drilling and Completion From the outset, the drilling process causes elasticity changes in the drilled formation. Certain elasticity changes are unavoidable because of the very presence of a hole in an elastic medium. However, changes in elasticity, physicochemistry and capillarity that ordinarily are avoidable often are precipitated by formation damage caused during drilling and completion. It is recognized that damage mechanisms are related to fluids that invade and/or react with the formation. These damaging fluids usually include aqueous phases that may cause the following:swelling and hydration of in-situ clays, dispersion of insitu clays, capillary phenomena or water blocking, migration of clays from fluid formulations, insoluble mud cakes, particle tilting, nongauge, wellbore, and unstable wellbore. Swelling and Hydration of In-Situ Clays All clays absorb water molecules on the surfaces and edges of individual particles. In addition, the montmorillonites, mixed layer clays and certain illites can hold large amounts of interlayer water. Thus, when aqueous fluids are used in drilling or completing operations, clay swelling can occur. These swollen clays plug flow channels and impair well productivity. plug flow channels and impair well productivity. JPT P. 671
Abstract The Shallow Clastics Field, which is operated by Sarawak Shell, primarily targets two shallow gas-bearing reservoirs, H1 and H2, at approximately 2,650 ft true vertical depth (TVD). An appraisal/early-producer well with a deviated wellbore was drilled through the H1, H2 targets, and a completion design consisting of a cased and perforated commingled completion inside 9โ5/8-in. casing was implemented. The sand-face completion design consisted of a large-OD expandable sand screen with 150 micron weave that opened across the 2 zones. Upon completion, the reservoirs were cleaned up through a temporary well clean-up and test facility to test productivity and evaluate integrity of the downhole sand-exclusion installation. Fines production, possibly due to a failure of the expandable screens, commenced almost immediately upon well bean-up and steadily increased to the extent that the well was deemed unproducible to the facilities. Because of the failure of the first well, a re-evaluation of the sand exclusion method that included more extensive core analysis and the completion types that would be suitable for development of the H1/H2 reservoirs was carried out. From this review, the operator and a service/ engineering company were able to develop an innovative sand-exclusion method that combined several new technologies. To date, four wells have been completed with the new well configuration and sand-exclusion method chosen to address completion needs. These have been tested, and to date, have proven to be operating satisfactorily. This paper will review the evaluation that led to the sandface completion design, the field implementation of the design, and the key installation success factors that were required. Results and a summary of best practices from the initial installations will also be summarized. Introduction Sarawak Shell's Shallow Clastics field consists primarily of two shallow gas-bearing reservoirs, H1 and H2, at approximately 2,650 ft TVD. These reservoirs are laterally extensive, covering an area of 200 sq km with an estimated gas in place (GIP) in excess of 2 Tscf. The reservoirs are made up of a sequence of highly laminated sand and shale deposits with significant sandsize variability and high fines content. Being highly unconsolidated, downhole sand exclusion is mandatory. The primary drive mechanism is a depletion drive based on the weak aquifers seen in existing fields in the area. The Shallow Clastics reservoirs overlay deeper Central Luconia carbonate gas reservoirs, which are already on production with further fields in development; therefore, a gas processing and gathering system was already in place. Gas from all the fields is produced to the Malaysian Liquified Natural Gas (MLNG) plants at Bintulu, East Malaysia. Production from Shallow Clastics is intended to counteract decline from other fields and is critical to maintaining the security of the supply to MLNG. Significant log data (Fig. 1) from Shallow Clastics were gathered from the appraisal and development wells of the deeper carbonate gas reservoirs; however, core data were limited to what could be generated from a single, poor-quality core from E11-SC1.
- North America > United States > Louisiana (0.28)
- Asia > Malaysia > Sarawak > South China Sea (0.24)
- Geology > Rock Type > Sedimentary Rock > Clastic Rock > Sandstone (0.86)
- Geology > Rock Type > Sedimentary Rock > Clastic Rock > Mudrock > Shale (0.55)
- Well Drilling > Well Planning > Trajectory design (1.00)
- Well Drilling > Drilling Operations > Directional drilling (1.00)
- Well Drilling > Drilling Operations > Coring, fishing (1.00)
- (7 more...)
Abstract Gravel packing long horizontal sections is an exceptional challenge in itself due to the lengths now being completed. When simultaneous gravel packing and effective mud cake removal is considered, the complexity of the process is compound, posing a more demanding challenge to the completion process. Previously, to gravel pack a horizontal well it was necessary to seal off the wellbore from the formation to such an extent that substantial circulation could be maintained during gravel packing. This implied the need of a filter cake in place that needed to be removed in a separate treatment after the gravel packing operation to achieve an efficient completion. The introduction of screens with shunt tubes eliminates the need for well circulation during the gravel packing operation, and therefore simultaneous removal of the filter cake while gravel packing becomes a viable possibility. In this paper we present an integrated approach to gravel packing and removal of the drill-in fluid filter cake. This was achieved by a combined application of a surfactant based carrier fluid in an enzyme and chelant breaker solution using shunt tubes for open-hole gravel packing. The shunt tubes ensure complete packing by allowing an alternate path for bypassing sand bridges that may form in the screen and formation annulus, due to excessive leak off. The carrier-breaker fluid ensures contact of the breaker with the filter cake in the entire interval during and after gravel packing. Clean up efficiency tests, fluid rheological behavior and fluid design are presented together with field case histories. These case histories demonstrate that gravel pack placement and well productivity index have been improved with respect to previous practices, while simultaneously reducing overall completion cost. Introduction The field where this work was performed is located off shore South East Sumatra, in the Indonesian Java Sea. The core samples taken in the initially drilled wells showed that generally the formation has poor sediment lithification and is fairly unconsolidated. As a consequence a sand control completion is required. The field was developed with vertical and slanted wells until 1996 when the first horizontal well was drilled. Since then in excess of 60 horizontal drains have been drilled in the field and completed with open hole gravel packs using the High Rate Water Pack (HRWP) technique. This is the common completion practice, which sometimes requires a stimulation treatment to remove the remaining drilling fluid filter cake and improve the well Productivity Index (PI). The challenge was to perform the long open hole gravel packing treatment while simultaneously removing the filter cake in a single treatment without compromising the results of either component of the completion process. Reservoir Description. The target reservoir was a thin sand body of the Talang Akar formation. This is a medium grain size, clean sand, deposited in a fluvial environment. It is characterized by a very high permeability in the order of 2 โ 5 Darcy, 29% porosity, moderate consolidation and sand production tendency. This reservoir lies at 3500 โ 3600 ft TVD and has a reservoir pressure of 900 to 1350 psi. It has a strong water drive that in most cases results in a rapid water breakthrough. Water cut is generally very high, with most wells making above 90% water.
- Asia > Indonesia (1.00)
- North America > United States > Texas (0.68)
- Geology > Sedimentary Geology > Depositional Environment > Continental Environment > Fluvial Environment (0.54)
- Geology > Rock Type (0.48)
This article is a synopsis of paper SPE 58743, "Successful Application of Oil- Based Drilling Fluids in Subsea Horizontal, Gravel-Packed Wells in West Africa," by M.R. Chambers, D.B. Hebert, and C.E. Shuchart, SPE, ExxonMobil, originally presented at the 2000 SPE International Symposium on Formation Damage Control, Lafayette, Louisiana, 23-24 February.
- Africa (0.56)
- North America > United States > Louisiana > Lafayette Parish > Lafayette (0.25)