Openhole completions with prepacked screens are increasingly the completion of choice for horizontal wells requiring sand control. For maximum productivity from these wells, preventing mud damage to the fonnation and the screens or removing it before bringing the well onto production is vital. A common industry approach to this problem is to displace the drilling mud to an aqueous clearfluid before production. typically followed by a breaker fluid. This paper details an alternative approach: bringing the well on without cleanup. The paper outlines the decision-making process, shows how the drill-in-fluid and cleanup operations are designed, explains how laboratory testing can be used to support the design philosophy, and highlights that quality control of the mud system while drilling is critical to the success of such a well. Case histories in two very different reservoirs are presented that illustrate the success of this approach.

Tfws papaf was sebcted for preaentatmn by an SPE Prcgram Canmmae following rewew of mfamahon Con! aineal In an abstract s.ulmm tad by the authcf (s) Ccmlcnw of ma papar as pfe8entad, have nof been revmwad by lha Society of Petrolaum Engmaers and ale subject to cm'rMon by the author(s) The ma!enal as pmsemed, does not necessary reflect any pomt$m of the SOmaty of Petrolmm Ewmemrs, is offcars, or mambars Pap-am presanted at SPE meslmgs are subpct to pubhcatum rewew by EdNortal Commt!ees of the Somety of Petroleum EngIn%ers Perm!swon to copy !s restricted to an abstracl of not more than 300 wofds Illustralons may not be cOpted The abstract shoulo conlam conspicuous &5muwk@tnenl of where and by whcm the paper was presented V/me L,braflan, SPE P O BOXS33S3S, Richwdscm TX TSCW-2836. U S A lax 01-21 4-952-W35Abstract A joint initiative between BP and Schlumberger began in mid-1994 to develop techniques for the diagnosis and treatment of unwanted fluid entries in high angle and horizontal wells. The first full scale test of the flow diagnosis technology to occur in a BP asset took place in an extended reach well at the Wytch Farm oilfield in November 1995.In order to measure oil and water flow rates it is necessary to measure both the hold-up and velocity of each phase. A novel toolstring combination was developed which incorporated new sensors especially targeted at the stratitied flow regimes encountered in horizontal wells and featured the capability of measuring flow parameters by several independent methods, enhancing confidence in interpretation.The new sensors could independently measure the velocity of the oil and water phases by measuring the time of flight of iniected Dassive fluid markers as well as bv the well . . established oxygen activation method. Fluid holdup was obtained from a nuclear carbon-oxygen ratio method and an imaging tool. Additionally the imaging tool, based on an array of local electrical probes, could give a real time representation of the distribution of hydrocarbons and water in the borehole. Conventional production logging measurements such as the spinner, pressure and temperature were also made.The primary objectives of the logging were to determine the oil and water flow profile along the cemented and perforated liner and monitor the movement of the reservoir oil-water contact. Entry points for oil and water as well as zonal contributions were confirmed by excellent correlation between the various logging sensors.

Tfws papaf was sebcted for preaentatmn by an SPE Prcgram Canmmae following rewew of mfamahon Con! aineal In an abstract s.ulmm tad by the authcf (s) Ccmlcnw of ma papar as pfe8entad, have nof been revmwad by lha Society of Petrolaum Engmaers and ale subject to cm'rMon by the author(s) The ma!enal as pmsemed, does not necessary reflect any pomt$m of the SOmaty of Petrolmm Ewmemrs, is offcars, or mambars Pap-am presanted at SPE meslmgs are subpct to pubhcatum rewew by EdNortal Commt!ees of the Somety of Petroleum EngIn%ers Perm!swon to copy !s restricted to an abstracl of not more than 300 wofds Illustralons may not be cOpted The abstract shoulo conlam conspicuous &5muwk@tnenl of where and by whcm the paper was presented V/me L,braflan, SPE P O BOXS33S3S, Richwdscm TX TSCW-2836. U S A lax 01-21 4-952-W35Abstract A joint initiative between BP and Schlumberger began in mid-1994 to develop techniques for the diagnosis and treatment of unwanted fluid entries in high angle and horizontal wells. The first full scale test of the flow diagnosis technology to occur in a BP asset took place in an extended reach well at the Wytch Farm oilfield in November 1995.In order to measure oil and water flow rates it is necessary to measure both the hold-up and velocity of each phase. A novel toolstring combination was developed which incorporated new sensors especially targeted at the stratitied flow regimes encountered in horizontal wells and featured the capability of measuring flow parameters by several independent methods, enhancing confidence in interpretation.The new sensors could independently measure the velocity of the oil and water phases by measuring the time of flight of iniected Dassive fluid markers as well as bv the well . . established oxygen activation method. Fluid holdup was obtained from a nuclear carbon-oxygen ratio method and an imaging tool. Additionally the imaging tool, based on an array of local electrical probes, could give a real time representation of the distribution of hydrocarbons and water in the borehole. Conventional production logging measurements such as the spinner, pressure and temperature were also made.The primary objectives of the logging were to determine the oil and water flow profile along the cemented and perforated liner and monitor the movement of the reservoir oil-water contact. Entry points for oil and water as well as zonal contributions were confirmed by excellent correlation between the various logging sensors.