The Gulf of Thailand is characterized by shallow-water depth wells with bottomhole static temperature ranging from 240 to more than 420°F. These wells are drilled to an average of 12,000 ft MD and 9,000 ft TVD with a fast paced-batch drilling strategy. Most cement jobs are done offline, and on the surface section can be as frequent as 6 jobs per day. With multiple rigs, operators can require more than 100 cementing operations per month and cement volumes as high as 18,000 bbl. This efficient operations environment creates a demand for a logistically and operationally simple cement system that can be applied in all well sections and across the full range of expected temperatures. An advanced, lightweight seawater-based cementing concept was tested for this application. This new cementing system uses a single blend with only 3 to 4 primary liquid additives (including a stable, high-temperature, multifunctional polymer) to adjust all primary cement jobs for the entire wellbore. A sophisticated lab testing program was conducted for the innovative cementing concept according to the required demands on cement slurry design given the harsh wellbore conditions in the Gulf of Thailand. Tests revealed that the developed cementing systems meet all well requirements despite low densities of 13.3 to 14.0 ppg with high water content. This advanced cementing system was introduced in 2011 and has gradually been used on all wells since then -to date more than 500 wells in the Gulf of Thailand. In addition to improving logistics, use of the system has enhanced cement bond quality in production tubing cementing jobs. This improvement also reduced pay at risk due to insufficient cement isolation. This is evident in the whole range of well temperatures.

The Gulf of Thailand (GoT) is characterized by shallow-water wells that are hot and deviated; with low fracture gradients and average bottomhole static temperatures of 425°F (some wells can approach 520°F). Drilling depths average 14,000 ft measured depth (10,000 ft vertical) and fast drilling practices are used for slimhole monobore completions, resulting in daily cementing jobs from each of the offshore rigs. This paper will present an advanced lightweight seawater-based cementing concept using a single cement blend with only 3 to 4 primary liquid additives (including a multifunctional polymer system) to adjust all primary cement jobs for the entire wellbore. A sophisticated lab testing program (such as analyzing slurry gas control) was conducted for the innovative cementing concept according to the required demands on cement slurry design and the given harsh wellbore conditions in the GoT. Valuable design-effect relationship elements found in this study (such as the impact of the multi-functional polymer on cement expansion) will be discussed for applications on other upcoming and challenging drilling projects in Asia. Tests revealed that the developed cementing systems meet all operator and well requirements despite their relative low densities of 14.0 ppg with high water content. The advanced lightweight cementing design has been successfully pumped in greater than 450 GoT offshore wells starting with just a few wells in 2011 to most wells in 2013, and its performance was compared to previous cementing systems. Lab test results, pre-job planning, cement job execution and cement bond logs are evaluated and discussed. The case histories conclude that the advanced lightweight cement design significantly improved the quality of zonal isolation in wellbores.

The Gulf of Thailand is characterized by shallow-water depth wells with bottomhole static temperature ranging from 240 to more than 420°F. These wells are drilled to an average of 12,000 ft MD and 9,000 ft TVD with a fast paced-batch drilling strategy. Most cement jobs are done offline, and on the surface section can be as frequent as 6 jobs per day. With multiple rigs, operators can require more than 100 cementing operations per month and cement volumes as high as 18,000 bbl. This efficient operations environment creates a demand for a logistically and operationally simple cement system that can be applied in all well sections and across the full range of expected temperatures. An advanced, lightweight seawater-based cementing concept was tested for this application. This new cementing system uses a single blend with only 3 to 4 primary liquid additives (including a stable, high-temperature, multifunctional polymer) to adjust all primary cement jobs for the entire wellbore. A sophisticated lab testing program was conducted for the innovative cementing concept according to the required demands on cement slurry design given the harsh wellbore conditions in the Gulf of Thailand. Tests revealed that the developed cementing systems meet all well requirements despite low densities of 13.3 to 14.0 ppg with high water content. This advanced cementing system was introduced in 2011 and has gradually been used on all wells since then -to date more than 500 wells in the Gulf of Thailand. In addition to improving logistics, use of the system has enhanced cement bond quality in production tubing cementing jobs. This improvement also reduced pay at risk due to insufficient cement isolation. This is evident in the whole range of well temperatures.